Science topics: GeoscienceCartography
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Cartography - Science topic

Cartography is the study and practice of making maps. Combining science, aesthetics, and technique, cartography builds on the premise that reality can be modeled in ways that communicate spatial information effectively.
Questions related to Cartography
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I have a bachelor's degree in topographic engineering and a master’s degree in remote sensing and geographic information systems, and I am looking for a title for a PhD research related to cartography or one of the modern applications of geographic information systems.
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You may check the International Cartographic Association (ICA)'s commissions: https://icaci.org/commissions. In addition, you can check the journals in cartography and/or GIS such as International Journal of Geographical Information Science, Cartography and Geographic Information Science, International Journal of Cartography, Transactions in GIS, The Cartographic Journal, Cartographica, KN - Journal of Cartography and Geographic Information, Geocarto International and International Journal of Digital Earth.
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Such question is raised when we want to know the future development of research paradigms in educational and social research after we endeavor to compare and evaluate them. I have pondered such question for 18 years. I would like to see if you could join me to answer such epistemologica and ontological l question.....Recently, I have found a feasible method called social cartography. .....
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Saludos colega.
Recomiendo analizar la obra "A LA CAZA DE LA REALIDAD"
DE LA NUEVA POSTURA FUNADAMENTAL EPISTEMOLOGICA, CUYO AUTOR ES ÉL DOCTOR "MARIO BUNGE".
ALLÍ tienes muchas respuestas válidas. Felicitaciones
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Hello, for an article I am looking for maps of the Crimean peninsula (ideally textbooks or atlases) from Russia and Ukraine to compare. Does anyone have appropriate materials or know of suitable contacts (textbook publishers or universities)? Best regards.
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Sorry, I don't have maps of Crimea
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Are there any iPad pro apps for GIS mapping and analysis? Thanks
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Dear Jens Kleb Antônio Carlos Pereira dos Santos Junior Omid Vakili , for precision monitoring I use an emlid reach rs2+ GNSS antenna and its app is well supported by apple so this doesn't worry me. My basic idea is to use the iPad as if it were a topographic map on which to digitize with the pen in the field or in the laboratory the various shapes obviously geo-referenced and using as a base map a topographic map in ecw format, export in shape format and load everything into my beloved QGis, but taking full advantage of the potential of the apple pencil. Is this possible? I must also admit that I am a big fan of global mapper. Regards
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I often come across those two fascinating terms (rather associated with the disciplines of geography, geology?) in titles of papers on literature and literary criticism. Although I often read those papers with interest and enthusiasm, the difference between the two terms which are commonly used with prepositional phrases as in "topography of desire", "cartography of love and loss", "topography of pain.." etc. remains blurred to me.
What would make you (or any researcher, writer interested in literary criticism) choose one over the other? Or, when would you opt for 'cartography' rather than 'topography', for instance? Your decision, would be based on what?
Thank you all!
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Topography is the study of the land features on the earth surface and cartography is the science and art mapping features
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I am characterising a volcanic deposit in which I am currently imaging at SEM the fine ash (>4 phi). For each sample I do a 500um-wide elementary cartography. I know that by superposing filter you can know which component are present but for the proportion I am worried since here I would have a ratio of surfaces and not of weight (As I have for bigger fractions between -7.0 and -0.5 phi).
Should I multiply the surface area of each component by it's density (using densities of the various components) assuming EVERY component is 1 um thick (which it is the worring assumption for me) ? This last assumption allow me to transform a surface to a volume and then to end up with a mass and not a mass.m-1.
Thank you in advance !
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yes ,you can
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I am looking for feedback from English language learners who have developed their language skills through the fields of Cartography/Geography.
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Long ago, I was a polish kid with an open mind and a wish for learning new things about the world. I was always curious about distant places and exotic lands. I love maps and atlases. They are very useful tool, especialy at school, but they also bring so much joy for young readers. I cherish many beautifuly ilustrated books and encyclopedias given to me by my mum. She hoped to spark in me intrest to learn and to think about our world, its problems and hidden treasures. I enjoyed learning English too in my early childhood. Sometimes I enjoyed it much more than learning about my mother tongue! At some time, I was given a lesson by my Godmother to folow my personal interests by using English language. She said - "Do what you want, and read what you want, but read it in English!" And that's a secret. This is how I polish my English right now. I have still much to learn thow. I also keen on Tolkien and his works. He was a linguist, and he created magnificent world resembling one of my favourite epochs in history, the transistion time between Late Antiquity and so called Dark Ages. He introduced me to a world of ancient ethymologies, roots of words, and forgotten meanings. The marvelous odyssey of early germanic peoples, Saxons, Jutes and Angles seeking new home in Auld land of Brittania. From humble origins, as pirates, mercenaries and auxilaries from today Niedersachsen and Denmark, they have established petty kingdoms and so called English Heptarchy, and then, they have experienced truly heroic period led by Alfred the Great repelling pagan invasions. Gradually they united and developed their civilisation with a little help of the Normans :) Their world was transforming, jus as their language, reciving another wave of new words of romance origin. It is so fascinating! Now lets talk about a couple of words wich still retain their archaic meaning. Oxford for example, the name implies it was a river crossing. We have many place names ending with -shire, or -borough. Such words can tell us much about old administrative systems. We have place names with endings like -by, or -ville. We can see clearly that they have a foreign origin, Viking and Norman respectively. Lets talk about Newfoundland - it is so obvious it doesn't need any explanation at all. I could add many more examples. To sum up, there are plenty of reasons why Geography can help us understand language and culture of particular country. I hope my way too long text was just a little bit helpful to You. God bless You and stay healthy!
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Tell me about the apps you can’t live without
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Hi
The UTM Geo Map software is so good for android.
Goodluck
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Aim is to find signal value at x0 from signal values at xi, i=1,..N using Kriging, given as Z(x0)=sum(wi Z(xi)).
After fitting a non-decreasing curve to empirical variogram, we solve following equation to find the weights wi's-
Aw = B,
where A is padded matrix containing Cov(xi,xj) terms and B is vector containing Cov(xi,x0).
In my simulation setup, weights often have negative value (which is non-intuitive). Am I missing any step? As per my understanding, choice of curve-fitting function affects A. Weights are positive only if A is positive-definite. Is there a way to ensure that A is positive-definite?
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I think the problem is that the sample space of the variables considered has not been taken into account. Kriging in any form (simple, ordinary, ...) has been devised for real random variables, with support the whole real line, going at least conceptually from minus infinity to plus infinity, and endowed with the usual Euclidean geometry. In such a case negative weights would be no problem. If you expect positive estimates, than the variable is not supported on the whole real line, and you need to take this into account. In the field of compositional data analysis you can find tools to adress this problem. The essential tool is to determine the natural scale of your data, to find appropriate orthonormal coordinates for your data, and to perform estimation in the resulting representation of your data.
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As an electoral geographer I often present various electoral maps. I would like to create some contiguous cartograms in ArcGIS software but I have problems to find any geoprocessing tool that will work. If you have any advice for me I would be very greatful.
Thank you for your answers.
Best regards,
Radek
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A free tool can be found here:
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Maps are seemingly produced in ever-increasing numbers without principles of sound cartographic design. For example, despite the publication of successive cartographic texts and blogs that advise against the use of absolute numbers for choropleth maps, the practice is widespread in mapping cases of COVID-19. How can we ensure that cartographic design theory is implemented more widely?
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I think that each time you have to take a better look of your data. For example, like Cédric Aurelien Nguimdo Matsaguim said about highlighting differences at small scale like in the covid19 pandemic case. Nevertheless, each case of data must be addressed in a way that thematic maps would not lie or hide the truth...unless this is the goal!
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Major details about their interrelations, their major uses and functions.
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See this article, It may help you.
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If we are interested in carrying out the geological mapping of a certain territory, then, how could we use aero-geophysics and to solve which tasks? Of course, we could also consider satellite information available. Opinions?
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Henrique Joncew,
It is true that geophysics is a tool, but it has specific and general tasks that cannot be solved by conventional geological methods.
Geophysics allows, in conjunction with geology, to solve numerous aspects in geological mapping. For example, conventional geological methods can only explain what is seen directly by the surface geologist. In its aid, geophysics makes it possible to propose geological features that cannot be seen with the naked eye: geological strata and bodies at certain depths; presence of the water table; presence of contacts or faults that do not emerge, etc.
The advantage of aerogeophysics is given by its speed and the possibility of covering large areas where, at times, it is unlikely to develop land campaigns. The rapid development of remote sensors has come to the aid of Geosciences and their combination with aerogeophysics, undoubtedly, allows solving tasks that just a few years ago would be unlikely.
In Cuba there is a 1: 50,000 aerogeophysical survey of the entire territory and certain areas at a scale of 1: 25,000. So, the idea of ​​the question is to exchange experiences with colleagues in other latitudes and thus improve our results.
Thank you very much for your help,
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Hi all,
I have built predictive models with the Random Forest algorithm. Now I want to create predictive cartography with these models. I have read about the R package "ModelMap" but I suppose there are others.. I appreciate any kind of information about techniques, programs, etc ... (better if it is supported by bibliography). Thank you!
Carlos Cerrejon
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You can use R software to develop the random forest model
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Is it time to re-examine the labelling of Africa's regions as North Africa and Sub-Saharan Africa? Should there not be a more modern term for the larger subdivision of Africa. One that communicates its larger land mass, population , historical, anthropological, genealogical and economical significance. While not sure of the origin, but sometimes these terms originate with cartographers or journalists and then persist in the language? We seem not to have persisted with labels such as Asia Minor and Asia Major (see map).  On the other hand, in the Caribbean there is an historical division of the Antiles as Greater Antiles and Lesser Antiles.  Is the label Sub-Saharan Africa still apprpriate?  If not, what would you recommend the larger Africa be referenced as ?  Greater Afica ?  Africa Major ?  Some other reference ?
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The term "sub Saharan Africa" is used to refer to countries on the south of the Africa continent. The Sahara desert acted as a blockade dividing the sub Saharan Africa from North Africa. Also the north has a unique Islamic features because they had contact with the Arab world even before the incursion of Europeans in Africa.
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I have seen this style of map images repeated in several articles, but was never able to find the software required or a method to reproduce them. Does anyone know how to obtain them?
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In case someone is still looking for an answer. I found this video explaining how to do it.
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I'm currently looking for data analysis program to conduct the stellar cartography/doppler imaging. Kindly, anyone provide me the tool to extrapolate for my on-going research?
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Zeeman Doppler Imaging via Surface Activity and Magnetic might be reliable factors to develop virtual mood. attached link will be helpful to you .
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Is it still available? :)
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Dear cartography fellows, are you please aware of any research articles on depiction of own-position on digital maps? I am trying to investigate how map users perceives and interprets the precision of own-position depiction in terms of location and direction.
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A possible starting point here - very old ( my first paper!) :)
Then, about uncertainty and self position:
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Can someone recommend any articles which discusses problem of generalization of maps? When you change resoliution or aggregate several territories into 1 you lose some information of data. A lot of articles are about population density and generalization problems which occured during different analysis methods.
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Does anyone know how to indicate a free reference on free geotechnology? Which conceptually encompasses all free geotechnologies?
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Very Good Ms Herve Parmentier and Rosa Aguilar
The Article: Open Collaboration for Innovation: Principles and Performance is very important. It is in line with what I mean when I talk about geotechnology. In Brazil, we have a conceptualization that I find quite interesting and comprehensive of GIS. It is proposed by Rosa (2005): Revista do Departamento de Geografia, 16 (2005) 81-90. Title of Article: GEOTECNOLOGIAS NA GEOGRAFIA APLICADA. Author: Roberto Rosa. This author puts a brief initial and interesting summary to the concept of geotechnology in space sciences: "Geotechnology is the set of technologies for collecting, processing, analyzing and offering information with geographic reference. Geotechnologies are made up of hardware, software and peopleware solutions that together are powerful tools for decision making.
Among the geotechnologies we can highlight: geographic information systems, digital cartography, remote sensing, global positioning system and georeferenced topography."
Herve Parmentier as you can check the links sent by Rosa Aguilar and in this my last link, your links are within the subject. However, I want to know a concept that involves all these and perhaps some other geospatial issues.
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I must do it myself, in paper, I mean, no drones or anything like that. Thanks a lot.
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Apart from the conventional documentation with transparent sheets outlined by Christian Meyer you should think about making a series of photographs - if possible from above (Nadir) with a ladder, a few scales of different scales and at least two- to threefold overlap between neighbouring photos - so you can calculate a model in a later step or send the data to a cooperation partner to do it for you.
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What could be the role of cartography in Big data processing?
The increasing amount of data encourages the creation of new methodologies for data processing, as well as the development of digital technologies. Both are progressively yielding new potentials and possibilities in the evolution of cartographic analyses, synthesis, visualization, and their applications. This trend also leads to new challenges in cartography due to dealing with the gathering, storage, analysis, and visualization of spatial information and data. Cartography is one of the few visualization disciplines to has always used, and correctly analyzed a huge amount of data, and represented them on different levels of preciseness according to the needs of potential users. The bridge between Big Data (BD) and society cannot be achieved by only existing technologies and computers. The presence of professionals should be more active in the process of transforming BD into actionable information for users.
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Big Data in cartography includes, above all, the visualization of the inter-relations between factors and categories of large data sets. A geostatistical analysis based on programming languages (R, Python) and algorithms for big data sets processing, embedded in GIS or used as additional methods, is a great too to deal with such tasks.
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I wish to utilize cartosat DEM, publicly available form bhuvan site. However, I have analyzed and seen that the elevation values from cartosat DEM are very similar to ellipsoidal height of GLAS/ICEsat altimetry data. Before I use the DEM data, I wish to know whether the elevation values show actual orthometric height or ellipsoidal height?
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Dear Ronak Jain and René Vázquez-Jiménez , Thank you all. I have got the answers.
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I would like to create an online digital map guide of the urban, social and economic characteristics of an area with a significant historical heritage. I will be very grateful for your contributions in terms of ideas, proposals, bibliography, examples of feild sheets, operational modes, GIS online ...
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Thank you @Julien Gloanec for your answer. Actually, we intend to know how to map the historical heritage, not the public health issues. Regards
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I am new for Generic Mapping Tool (GMT), but I would like to work through a few simple examples of generating legends (ie. multiple points or lines plotted on a single figure using psxy). In the following example, I want a set the location of Legend in the southwest (Inside bottom-left of axes).
gmt psbasemap -R-108/-105/31/35 -JM6i -Ba0.5 -K -P> New_Mexico.ps
gmt pscoast -R -J -Df -Gwhite -O -K -P>> New_Mexico.ps
gmt psxy Data1.txt -R -J -Sc0.5c -Gblue -O -K -P >>New_Mexico.ps
gmt psxy Data2.txt -R -J -St0.5c -Gred -O -K -P>>New_Mexico.ps
gmt psxy Data3.txt -R -J -Ss0.5c -Ggreen -O -K -P>>New_Mexico.ps
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Dear Abd-Elrahim Ruby,
I am also new in GMT, but I have found a good manual "Getting Sterted with GMT: An Introduction to Seismologists" by Matthew R. Agius, you can request a full-text, hope it will help you.
Best regards,
Katerina
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Dear colleagues! Would you kindly name books or maybe articles on the history of the cartography of the British Empire and / or spatial perceptions in it? How the British created maps of their colonies and conceived space as such. Of course, I know these two books: Edney M.H. "Mapping an Empire: The Geographical Construction of British India, 1765 - 1843" and "The Imperial Map: Cartography and the Mastery of Empire" (ed. by J.R. Akerman). Are there others of the same high quality? :)
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Dear Sir,
You can have a look at the following books... this is not an exhaustive list:
1. The Great Arc - John Keay
2. Making History, Drawing Territory: British Mapping in India, c. 1756-1905 - Ian Barrow
3. Mapping India - Manosi Lahiri
4. Historical Records of the Survey of India - Phillimore
regards,
Priyank
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Maps tend to be judged according to how good they look rather than how well they function.
Can form ever follow function in cartography?
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Yes, good map does not mean attractive one. Good map should be readable and giving enough and accurate information to readers and users according title, scale and aim.
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Suppose you have a set of point data which contains two variables (say var1 and var2), both of which have discrete values (say 1, 2, and 3). You try to map them (see attached files var1.jpeg and var2.jpeg for reference) and decide you want to see how similar these two data are in terms of statistics. You create a "matrix" comparing the values of the two variables (see sim.jpg) and obtain a %similarity by taking the percentage of the total count of all points which had the same value for both variables (e.g. var1 and var2 = 1, etc.) in relation to the total number of points.
Is that the only way to compare the two variables? What other methods can be performed to compare these two?
P.S.: Scatter plots are ineffective, since they only result in a set of 9 visible points (because the data is discrete, the only possible values for each axis is 1, 2 and 3, resulting in only 9 possible combinations of ordered pairs) (see scatter.jpg). Q-Q plots only show 5 points (see qq.jpg).
Thank you very much!
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If you want to make the statistical comparison between two functions it is possible to use the covariance functions. This is a procedure that will allow you to find statistical similarities between two time series. For this there is the theoretical definition from the integration operations and also several available computing algorithms. I recommend using the Matlab application which has built-in almost all covariance functions.
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I am trying to get morphometric data on Ouachita map turtles from a particular river system and going from website to website is inefficient if there is a one-stop-shopping alternative online.
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Greg... You can also try VertNet (http://www.vertnet.org/index.html).
VertNet has specimens listed for most of the bigger U.S. institutions.  You can narrow searches by typing in genus and species, and then also adding something like the county (or even the name of the collector).  Though some smaller collections or state collections (e.g., Mississippi Museum of Natural Science) are not patched in to the network.  
However, if you are looking to get morphometric data, you will need to contact the museum collections manager.  They may be able to take photographs with a scale bar (I've done this before) or they may be able to send them to you on loan.  Sorry, but most collections don't have measurement data entered into any database.
I hope this helps.
Best,
Will
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Kindly someone to help,how i can use fabric tool  in ArcMap to subdivide a parcel of land into equal portions of equal known area. if i just have  the polygon of the bounbary of the area of study..
Kindly step by step from scratch.see the image below of how i want to divide it 
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I hope Sir this will be helpful links to solve your problem
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DIVA-GIS is a mapping and visualization software
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Data-Interpolating Variational Analysis
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I have OSM data of the streets but, some of the features have missing names which could be seen on google map. Thank you for your kind attention. 
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Thank you sir. I will look into this.
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Am resample all dataset to 1km, and the available 1km rainfall data has missing records of 1990 and 1995
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Hi Joshua Irungu,
You may convert your low resolution grid to points (centroids), then use any software having interpolation feature, set output grid size 1km and try different number of influence neighbor points (hit and trail). Though not a good solution, but still you will get some better results.
Regards,
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Need a common projection for yamuna river shapefiles covering himalayas and plains of uttarakhand,uttar pradesh.
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I think for common projection ALBERs is better, as it gives equal area map projection that uses two standard parallels. Although scale and shape are not preserved, distortion is minimal between the standard parallels. LCC is mainly used for aeronautical charts.
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We are developing a server with historical maps and aerial photographs of San Escobar https://twitter.com/rpdsanescobar?lang=en https://www.facebook.com/sanescobarcountry/ Amount of data is relatively small (~12 TB), as the country is still young, but is going to increase soon. What would be better choice to store and edit such data (aerial images in raster format and maps in raster or vector): RAID 10 or RAID 5? From practical point of view: is the RAID 5 performing noticeably worse than RAID 10?
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The answer depends a lot on how you have the server configured as a whole. First, it is important to note that RAID isn't a backup solution. As such, I I write this with the assumption that you additional measures in place to back-up and restore the data as needed.
In terms of the configuration, two things you must keep in mind. First, regardless of the RAID configuration you select, if you do not use a RAID controller with a DRAM cache you will see poor performance since the on disk cache may be disabled. Second, the rule of thumb is that RAID 10 is generally significantly faster for random access reads and writes than RAID 5. Thus, RAID 10 is generally preferred for applications where performance is a concern and would make sense if you are going to be accessing and editing GIS data on a regular basis.
For a really nuanced response you likely want to consult with someone that deals with server hardware on a regular basis, but hopefully this is helpful!
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Hello.
I have a point shapefile representing the location of weather stations; for each point, the wind speed and wind direction (in degrees) is recorded. I need to create a cotninous surface (i.e., a raster) representing the wind direction in a given area.
In order to do that, I would like to follow the procedure described by:
Safadi, C., 2016. Wind and wave modelling for the evaluation of the maritime accessibility and protection afforded by ancient harbours, Journal of Archaeological Science: Reports 5, 348–60.
which in turn relies on:
Williams, R., 1999. Non-linear surface interpolations: which way is the wind blowing? Paper presented at the ESRI Conference Proceedings, 1999 (which can be found at the link provided below).
The procedure, which I do not totally grasp (as I will elaborate on in what follows), is graphically synthesized by Safadi in the attached image.
I understand that:
(1) the wind direction is first split into two components, using the sine and cosine of the wind direction, so obtaining two values indicated with X' and Y' in the attached image;
(2) the two components are interpolated, so obtaining two (separated) rasters;
(3) the two resulting rasters are used to calculate the alpha angle that, following the indications in the attached image, should be equal to TAN-1Y'/X'.
Now, what I do not follow is:
-in step (1) above, shall I take the sine and cosine of the wind direction only, or these must be multiplied by H (see the upper-left part of the attached image)?
-the last step of the procedure, the one that is indicated at point c of the attached image, is rather obscure to me.
Would anyone mind to clarify the above points, with possible reference to actual GIS (preferably, ArcGIS) procedures? Thank you for any guidance you will kindly provide.
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Hello.
I seem to have finally found a proper solution to the problem. I followed the method described by S. K. Grange (https://www.researchgate.net/profile/Stuart_Grange2), who was framing the method in terms of R coding. Anyway, I got some results that made sense. I checked, for instance, the interpolated direction values between two sampling points: the values in between made sense, while in my previous attempts there was not meaningful relashionship among them.
So, the u and v components were obtained:
u= -SPEED * Sin(2 * 3.141592 * DIRECTION / 360)
v= -SPEED * Cos(2 * 3.141592 * DIRECTION / 360)
In doing that, I followed Grange's advise to negate the wind speed (for the reasons that I referenced to in my previous reply).
After having interpolated the u and v values, the two obtained rasters were processed throught Raster Calculator to eventually arrive to a  wind direction raster, whose values in degrees were meaningfully expressed, without the need of extra calculation or conditional statements. The following is the formula used in Raster Calculator:
(ATan2(u, v) * 360/2/3.141592) + 180
As for the latter formula, it must the noted that (unlike other sources found on the web), u and v must be fed as first and second argument respectively into ATan2, NOT the opposite (as requested by other softwares).
Of course, this is valid for ArcMAP as far as I can tell.
Hope this will prove correct and, hopefully, useful to others.
Any further comment/suggestion is welcome.
Best
Gm
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I would like to make an analysis with QGIS with the tools such as geo-statistics, geo-referencing, and digitizing with this incomplete and rough sketches of the data. However, since the client does not have the proper information about the local coodinates, or any shape file that could contribute with the GIS, I have found out that by using Google Earth Pro, I could find a location which I am confident about that this would be the location in the sketch drawn by Mr. Mostafa El-Sayed, the surveying engineer, in the El Bahariya.
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Mr. Adi:
I found a very similar pattern on both images. I made a PDF with the coincident shapes: The circular patterns are not the same (perhaps that are not exactly the same date) but the shape of the parcel boundaies, that is curved on the left side (west side) seems to be the same). If you search for other coincidence, you will surely find another similarities...
If you now are sure that there are the same, I can help you later with the georreferencing...
Hope it helps.
Regards
Gabriel
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is DEM and DTM is synonymous? What is the difference between these two?
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Dear Firoz,
To my experience, a DEM is most of the time used as a generic term for DSM's and DTM's. Where: DSM = (earth) surface including objects on it;
                        DTM = (earth) surface without any objects.
This summarizes the terminology somewhat, though fierce discussions are still going on about the terminology depicted here.
Cheers,
Frank
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Application of GIS to determine centralized waste collection points. Case of Mutare City, Zimbabwe.
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Hi,
You can also try connecting ARCGIS ONLINE SERVER if you have a server license. It makes your job a lot easier as you can fully load a basemap in the backdrop and go on making your layers on top of it. In that case you need not download any basemap separately for your area of interest. Otherwise OSM is a good alternative. 
Regards,
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Hi everyone,
I need calculate fragmentation metrics from raster in an hidrografic basin. Someone knows a package from R for calculate: Number of fragments, total of fragments, distance of fragments and form of fragments?
Thanks,
Eduardo
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Thank's all for aswners. I will try SDMTools!
Best,
Eduardo
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I would like to apply Getis-Ord hotspot analysis on a tiff image of IHC  but do not have the know-how in this area. I was hoping to collaborate with someone that has the expertise in this application who would be able to walk me through this analysis from start to finish.
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Dear Jessica,
Me and my group we are currently developing a dedicated Plugin for QGIS to perform Hotspot analysis (Gi*) as well as Cluster/Outlier maps exploiting the PySAL Python library. The unreleased version is on GitHUB at the link below, while the stable version is on the official QGIS Python Plugin Repository.
The computation is based on vectors layers actually (i.e. shapefile), but I guess this would not be a problem using proper conversion tools.
If you are interested in further details I will be delighted to help you.
Best,
Daniele
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I studied in detail files published by BTS about CTPP files. I found following subdivisions are used:
1-State
2-State-County State-County
3-State-County-County Subdivision                                                                                             
4-State-County-County Subdivision-Place/Remainder                                                                   
5-State-County-Tract                                                                                                                              
6-State-Place                                                                                                                         
7-State-County-MPO Detailed Summary Level
8-Urban area
9-State-County-Census Tract-Block Group
Also following units are used:
Traffic Analysis Zone ,Consolidated Metropolitan, Statistical Area-Primary ,Metropolitan Statistical Area Consolidated code.
What is the reason for these divisions as they could only consider for example only three types of units and subdivisions?
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Beyond that, different subdivisions are needed for different applications.  Let me give you an example that I use in my own research in the redistricting processes in the various states:
Election data is available in the United States actually pretty quickly, but at the county level only.  What happens is that the clerk counts all of votes at a polling places and then calls those in to the Secretary of State.  These are then pushed up to the county level.  If you watch CNN or otherwise on election night, those are the maps you see.
Now, let's say you want to talk about the efficacy of the redistricting process.  To do that, I need to be able to simulate districts from the map that were not drawn in a biased manner from an established set of rules employed by the various states.  The county data is not as helpful because it is a dubious proposition that the counties themselves balance (and that's not how that is done anyway).  The districts are drawn by aggregating precincts, but that data is harder to come by.  The only complete set I can find for that is for 2008 (a landmark historical election because of the victory of a minority candidate for the first time).  There is a political philosophy called even swing which says that the effect of excitement or subduing of a voter base by a particular candidate can be assumed to be systematic across a population in an area.  By that level, if you want to predict the precinct level vote in 2012, you find the precinct votes for 2008 and the county votes for 2008, compute the percentage of the Democratic vote in that county that came from that precinct (and ditto Republican), and then use the 2012 county data to adjust the vote totals against that percentage.  That requires both levels of data, even if one is attainable from the other.  If you go back to my previous answer, that is terribly inefficient to have that only as the precinct file for that purpose.
So my previous answer is the theoretical answer.  It has to do with aggregation and the computational efficiency of it.  The practical answer is you often need multiple levels of that data for various reasons.  If multiple people need the same sorts of files, it is in the best interest of the distribution agency to take care of that for the users.
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I need to statistically compare two maps in order to determine if the spatial distribution  of their data is correlated or not. any suggestions? Thanks!
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I am replying to this question since I recently came across a similar issue. I will give my two cents here, bearing in mind that this solution applies to the specific issue at hand.
I have two rasters, each representing two path systems (actually, two least-cost paths networks). Each cell belonging to each path is given a value of 1, the off-path cells are given 0. The rasters have the same resolution and spatial extent.
I wanted to quantify if and to what extent they can be considered correlated, that is how "strong" is the overlap between them. I focused on the Jaccard coefficient (e.g., http://people.revoledu.com/kardi/tutorial/Similarity/Jaccard.html). 
This coefficient is equal to: the INTERSECTION between the two rasters divided by the UNION between the two rasters.
Now, in terms of this specific example, the INTERSECTION is the number of  only those cells that the two rasters have in common (i.e., the number of overlapping path cells). The UNION is total number of path cells (belonging to either of the two rasters).
In ArcGIS, we can use RASTER CALCULATOR to compute the INTERSECTION and the UNION.
To get the INTERSECTION, we just feed the following formula into RASTER CALCULATOR: "RASTER A" & "RASTER B" (where Raster A and Raster B is the name of the two rasters being analysed).
The same for UNION: "RASTER A" | "RASTER B"
Once we have obtained two new output rasters, to get the Jaccard coefficient, we simply open the attribute table of the two rasters, and take note of the cell count that has value equal to 1, dividing them accordingly (rememeber: INTERSECTION divided by UNION).
In my case, the count of cell with value 1 in the INTERSECTION raster is 22,822, while in the UNION raster is 37,716. The Jaccard coefficient turns out to be about 0.61
I hope this quite long reply will be useful to anyone that will jump here in the future.
A similar approach (in Matlab) is provided here: http://kawahara.ca/matlab-jaccard-similarity-coefficient-between-images/
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Are there any GIS data or open street maps available for Varanasi, India?
Similar to that of Dharavai Mumbai.
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All OpenStreetMap data are avivable for free. You can get raw data through overpass api via https://overpass-turbo.eu/ or QuickOSM plugin in QGIS. Also you can download some prepared dataset from OSM data - for example from http://download.geofabrik.de/asia/india.html but I don't know if these are detailed enough.
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The problem happens after having the DEM, then I do the process of determining the slope and I get a new map in which the data do not correspond, it does not calculate it, then in percentage, because when I do it with grades, it only takes me two Ranges, one low and one high. For example I do not give the percentages, but very high values (0-7101609412, 7101609412-2485563294, etc.)
I have done it in ArcGis and QGIS, all the same happens, I have also used different types of DEM and nothing.
Thank you very much for the help you can give me.
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I have the information of 150 companies in terms of their location (latitude and longitude) throughout the UK.
I would like to identify the location for the waste collection centre for all of them, so it requires all of them to be clustered/grouped which will minimise the total travel distance. Each cluster may have their own waste collection centre.
How this clustering can be done? Maybe companies in 50km radius in one group, etc? Anyone can help me on this?
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in using the k-means formula try to use the haversine distance instead of the Euclidean distance.
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I'm looking for shapefiles for all IBAs in Turkey, Armenia, Georgia, and Azerbaijan. I have contacted BirdLife with no response. Anyone have files to share or know of where I can get them? Thanks-
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Hola Evan, you can request this information directly to BirdLife.
All the best,
Adrian
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Hi anybody, 
we have bought Emotiv EPOC EEG and have it connected to SMI RED eye-tracker. Does anybody have an experience of such data analyses? 
We do not believe to "emotions" that are displayed directly in SMI BeGaze, so we would like to anylyse raw data. 
Our research is focused on cartography, so we would like to analyse EEG data recorded during presentation of different types of maps. 
Thanks for any help
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Hey all,
To my knowledge, both systems are compatible with the lab stream layer platform LSL (check it out here: https://github.com/sccn/labstreaminglayer). We use it with our systems for a couple of years, and it seems to be working very well.
Let me know should you have more questions. 
Disclaimer (I am affiliated to none of the mentioned companies, but we produce mobile EEG devices and use LSL to sync them with other systems, so I really recommend it. It is open source and free).
Bogdan
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Hello, I am very familiar with producing isochrones maps in ArcGIS by implementing Tobler's hiking function. I was wondering if anyone here is familiar with QGIS' r.walk module which is used to calculate anisotropic cumulative cost surfaces, and if anyone knows about a good (online) resource that provides a step-by-step guide.
regards
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I will be obliged if any one can provide me the above mentioned map.
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Please contact to  Dr. Kazmi Geography Department UoK.
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If I was used a Geological map of an area, and it was re-exported with a new colors and symbols differ from the original. Is this considered as a modified map?
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That would be exactly my answer, too.
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how can i draw the deteriorations from photos and walls?
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if you can digitised contour and dem data u can use mapping in global mapper and surfer
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 I am looking for shapefiles for all the individual districts of India. Can anyone help me in finding INDIVIDUAL shape files, separately for all the districts over India.
Thanks
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Hi Md Waseem,
I agree with Ram, Diva-GIS/GADM.org is a great data source for geospatial data.
If you need individual districts and you have just combined layer for the entire state, then you can easily obtain individual shapefiles in any GIS software.
In ArcGIS, you can use Split (Analysis) function or Split by attribute tool (see the link below). In QGIS use Split vector layer function. Then you just pick the unique identifier (Name, ID, ...) and  you'll get individual shapefiles as a result.
Regards
Lukas
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I am looking for information about Francisco Gali, sailor and cartographer of the sixteenth century. Also it is known as F. Stroza Gali, Galy or Gally. It seems that was known to Sevilla and traveled to America, he lived in New Spain and made several trips of exploration by the west coast of North America. In 1584 he traveled from Acapulco to the Philippines, writing the chronicle of his journey that was later published. However, nothing is known (at least I have not found) Gali before traveling to the New World.
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Buenos días Manuel:
No tengo respuesta a tu pregunta. Quizás sepa algo José María Gentil.
Un abrazo
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Greetings, International Development Advisor, currently in the field.  So, this issue is a bit pressing as I am providing support for Primary Health Care clinics.  A simple Python script works in the ArcMAP Python Window, but not in the Field Calculator.  I have attached a screen capture.  I'm trying SQL layer definitions as a workaround.  Thanks!  
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Thank-you!
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What is meant by intimate cartography in literature? How could it be applied then to representations of space and place in modern poetry in particular? Or does 'intimate' simply bias towards the positivity on the portrayal of different places?
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Mohammed sir,
First of all Thanks a lot for your Question because You enlighten me with answers. Ahmad Gholi sir
Your answers were really helpful for me with Regards.
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Exploratory data analysis (Tukley, 1977) is a solution. But did someone experience any other solution to indentify the link beetwen land use changes and urban mobility ?
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Do you know depthmapX tool??
maybe it' coukd be a good solution for your question
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Maps and other kind of geovisualizations such as globes, interactive 3-d worlds etc. seem to be very popular and fascinate a lot of people. But what is the reason for this (just aesthetics, potential immersion/fantasy firing, exploratory spirit, ...)?
Well, of course there are a lot of threads in the Web that deal with this question. But for me, the answers I found there are not really satisfying (often fuzzy, not pointing-out the core issues). Who knows research works, scientific papers, or useful Web-links addressing this topic?
If we knew what makes geovisualization such interesting, maybe we could export these ideas and concepts to other domains, e.g. to set-up interesting user interfaces for (non-geospatial) applications, or to design innovative experiental spaces, etc.
I'm curious about your thoughts and ideas!
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The question focuses on the meaning of visualization in people's way collecting information. Vision is a  sense having highest capacity for collecting information in five people's natural senses, hearing, smell, taste, touch, and vision. Vision has been keeping 70 - 80 % information collected by a person every day. Hence, people perceive and understand easy information implied in image, graph. Map as a graph represents visually objects and fields at locations. The visualization of locations and attributes of objects and fields on a map assists people to perceive easy and understand better the objects and fields at locations. This is why people like map and geovisualization.
About the role of vision in people's perception of information may be found in:
S. Few, "Tapping the Power of Visual Perception," Perceptual Edge, pp. 1-8, September 4, 2004.
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Valentin de Ampudia was a noted map maker during his two decades of active duty with the Royal Engineers, mainly active in the northern provinces of Mexico, ca 1815-1822. I believe he either married a relative of one of the last viceroys (Grimarest), or his mother was of the Grimarest family, and (by then I believe his rank may have been Col. or Lt. Col.) Ampudia may actually have left Mexico to return to Spain with the Grimarest family at the same time the viceroy was deposed? Also, does anyone have a clue if/where any drawing/painting of him was ever done? Mil gracias!
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Dear Bob,
thank you for the Johnson History. - In my book "Korporierte im Amerikanischen Bürgerkrieg" I had considered already:
Albrecht Ludwig von Röder, who was fencing in a student duel with Bismarck in Goettingen in the year 1832, Joachim von Röder, Otto von Röder and Ludwig Socrates von Röder.
kind regards
Ruediger
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Dear colleagues,
I am working in national cartography of dengue and malaria risks in El Salvador using GIS. I am using Hierarchy Analysis Method, and one of the factors that I took into account is annual rainfall. I grouped each subfactor in different weights 1, 2, 3. For example according scientific literature about the relationship of Aedes mosquitoes and temperature: 1- (average temp less than 13 C) - Low mosquitoes activity; 2- (average temp. 13-20 C - moderate activity; 20-33 high activity). I found a lot of references that speak about the importance of rainfall (linked to humidity conditions) about mosquitoes proliferation, however I didn't found any reference about rainfall thresholds. Could you give me some references please? Thank you very much for your kindly attention.
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The nearest airport or seaport around you will have meteorological data that you can use. You may collect samples for a month or two to have a trend in relation to rainfall during the rainy or dry season. These values will guide you in predicting or correlating other months or seasons.
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I have metadata in my .dat file that tells me that my cell size is 0.200 degrees longitude. I want to import this file into GIS and convert my points to raster.
My file is very simple: it has x, y coordinates and the environmental variable. Its coordinate system is in NAD83.
I am wondering what value I have to input for the cell size when I am using the point to raster toolset in ArcMap. I have two different files with two different resolutions (one is the 0.200 degrees longitude and the other is 3km2) and no other raster file to compare it to; and so for cell size do I input 0.2 and 3 respectively.
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NAD83 is a geographic coordinate system based on ellipsoid. The measure unit of longitude and latitude (indirectly length) on ellipsoid is DMS (degrees, minutes and seconds).
Conversion between angular and linear units is not so simple, because it depends on geographic latitude. As we move away from the equator, parallels become smaller, so one degree becomes shorter in linear units (e.g. meters).
We could use the length of meridian for rough conversion in meters because all meridians have the same length.
One angular second is approximately 30,7 meters long. 0,2 degrees is 720 seconds, so the cell size (length) is about 22,1 km. Second raster probably hasn't cell area 3 km2 because resolution is defined by lenght. That means it has lenght between points 3 km. If cell area is 3 km2, then length is 1,73 km.
Obviously, you have a problem with defining the measure units. Maybe you could transform data in some projection (which uses rectangular coordinates xy and meters as measure units), so it would be easier and more intuitive to define resolution in meters.
BTW, which software do you use?
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I would like to determine the river mile of 25 sites along the Ohio River (USA). I understand that there is an ArcGIS tool for measuring the distance between two points, but I am not sure how accurate this method would be for a river that stretches nearly 1000 miles. Is there an interactive map or GIS data layer that will show river mile by clicking on any point of the river?
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Ben, there are two ways you can find out the river mile along the Ohio River between two locations: 1) using the navigation charts from the US Army Corps of Engineers, and 2) using USGS' Streamer. Let me briefly explain below. 
1) Method 1 - navigation charts: Go to this web: http://www.lrl.usace.army.mil/Missions/CivilWorks/Navigation/Charts.aspx. Open any of the nine navigation charts, for example, Charts 1-5. Take a look at the chart index (page 20) and find the chart number for the location you are interested in.  Open that chart and you will see river channel maps with a blue sailing line and blue dots with numbers above. Those numbers are river miles.
2) Method 2 - streamer: Go to this web:
http://nationalmap.gov/streamer/webApp/streamer.html. Zoon in to the area you are interested in. Say, you want to know the distance between Cincinnati and Louisville and you can do the following: click on "Trace Upstream"; click on  Cincinnati and you will see a red line liking the city all the way to the Gulf of Mexico in southeast Louisiana; Now, move your mouse on the red dot at Cincinnati, you will see the total river mile from Cincinnati to the Gulf (i.e., 1580 mi); Now, clink on "Clear Map" and do the same as above for Louisville and you will the river mile from Louisville to the Gulf (i.e., 1443 mi); The difference between these two river miles is the distance between Cincinnati and Louisville.
Hope this helps.    
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I am doing a research paper on cartography. I know that there are different opinions regarding the most useful type of projection map. I'm just looking for some opinions and why you think, for example, a Peters Projection is more useful in today's world than a Mercator Projection. But, it doesn't need to be narrowed down to that. This is just one idea. 
Thanks, Sam Rubin
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Hi Samuel,
I agree with Richard.
The main reason for choosing a projection system is to be found in the geometric characteristics of the map  in relation to it's purpose.
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I am developing a huge database about cultural water heritage and I would like to relate it with the data mining methodologies...
Thank you all
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My PhD thesis employed data mining of historical maps for the case studies of land development patterns influenced by Land Readjustment projects in the urban fringe of Tokyo. I did this in part by bringing the maps into a Geographic Information System, and measuring the differences in land development inside and outside of project areas. This resulted in a number of publications:
Sorensen, A. (1999). 'Land Readjustment, Urban Planning and Urban Sprawl in the Tokyo Metropolitan Area.' Urban Studies 36(13): 2333-2360.
Sorensen, A. (2000). 'Land Readjustment and Metropolitan Growth: an Examination of Land Development and Urban Sprawl in the Tokyo Metropolitan Area.' Progress in Planning 53(4): 1-113.
Sorensen, A. (2000). 'Conflict, Consensus or Consent: Implications of Japanese Land Readjustment Practice for Developing Countries.' Habitat International 24(1): 51-73.
Sorensen, A. (2003). Megalopolitan Development and the Transformation of Rural Japan: Sustainability Implications of Extended Metropolitan Regions in Asia. Human Settlement Development section of Encyclopedia of Life Support Systems (EOLSS), Developed under the Auspices of the UNESCO, Eolss Publishers, Oxford ,UK, [http://www.eolss.net]. S. Sassen. Oxford, Eolss Publishers.
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I am trying to create an overlay between different (digitised) historical maps and the current map of a city in GIS. What methods are there to reconstruct historical maps in such a way that they accurately overlap with modern geodata?
I currently have the digitised version of three historical maps which were drawn at different scales (1:10.000, 1:5000, 1:2000) and in different projections.
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In addition to what has already been said about georeferencing, note that the Ground Control Points (GCPs), i.e. the set of homologous points you have to collect on the digitized image of the historical map and the current cartography, should be chosen as points which have preserved unchanged over time. As an example, if you can recognize the same building, pick up a points on its corners. According to the accuracy you want your final product to have, as current cartography don't use a raster map or a Google image (which can have large errors), but try to see if an official vector cartography (possibly at a large scale) is available.
After collecting GCPs, you have to choose a suitable georeferencing model. There are many models that you can choose from (and that you will usually find implemented in GIS software). The results of the transformation can be very different so be careful at which model you choose. To evaluate the georeferencing result, you should use some of the points you have collected as Check Points (CPs), i.e. points not used to compute the model but to validate it. A typically used statistics to evaluate the georeferencing result is the Root Mean Square Error (RMSE).
About the software usable to perform georeferencing, I can suggest the QGIS Georeferencer plugin (which however has some limitations) and the photogrammetric software PCI Orthoengine. The first is open source and available for free, the second is proprietary and available by paying the license.
I suggest two publications that better explain all my points and give you a practical example of georeferencing:
1) Brovelli M. A. and Minghini M. (2012) Georeferencing old maps: a polynomial-based approach for Como historical cadastres. e-Perimetron 7(3), pp. 99-110.2) Brovelli M. A., Minghini M., Giori G. and Beretta M. (2012) Web geoservices and ancient cadastral maps: the Web C.A.R.T.E. project. Transactions in GIS 16(2), pp. 125-142, DOI: 10.1111/j.1467-9671.2012.01311.x
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I have to perform imaging for study area 10x10 km which UAV specifications will be perfect to do this imaging task?
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Dear Essayas for your valuable explanation
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Can anybody help me about advantage of using geographic data rather than projected coordinate system data.
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Hi Nazmus, All,
This isn't a simple matter of advantages and disadvantages given one choice or the other. Yahya defines either coordinate system well. Lat & Long (i.e., the coordinates in a GCS) are angular measures, whereas the coordinates in a projected system (usually called Eastings and Northings, and usually defined in meters or feet) are distances.
If you're using ArcGIS, be careful in your choice. Arc conveniently performs the necessary conversions to make sure that two datasets defined in different coordinate systems draw on top of each other correctly (i.e., that the are correctly "registered" with each other). However, some of the geoprocessing tools do not do this for their calculations. An example would be performing some kind of distance- or area-based calculation on data that is defined in a GCS and not a projection (i.e., in lat/long, not meters). If you calculate the area of polygons on a dataset whose projection is in a GCS, and then do it again after reprojecting the data to a projected coordinate system, you'll get different numbers!
What's more, not all projected systems are the same. In the above case for calculating areas, you'll want to use a projection that preserves area (not all of them do), so that you get numbers that reflect the real surface.
When you're study area is very small (say, the size of a city) these effects are sometimes negligible. But the larger the area you're focused on (i.e., the smaller the cartographic scale), the more these considerations matter.
It's a somewhat complicated topic that most GIS literature just glosses over, but it's very important from an accuracy point of view. I recommend reviewing map projections; the Esri page Yahya links to is a good place to start, as well as the "further reading" links below it.
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I analyze the evolution of soil erosion in several dates and in several basins of Andalusia (Spain). The cartography which I possess is raster, and I am applying with ArcGis the slope of the regression curve to see trends of increase or decrease of the values in some periods. Can you recommend some papers related?
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Does anybody have a set of references for literature about map use (cartography), ideally from the 1500's to date? Not map design methods, the politics of representation with map-houses of the 1850's, or disputes over projection etc., but specifically on how maps have historically been used (and perceived as objects) in everyday life e.g., how they were incorporated into school syllabus, how they were used in leisure activities, how they were integrated and dissiminated in the post-WWII rebuild etc. 
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About the role and use of maps, i think you can find useful the review papers in cartography epistemology.
For example :
BALDOCK E. D., 1966, “Milestones of mapping,” {Cartographica: The International Journal for Geographic Information and Geovisualization} vol.3, n°2, p. 89-102.
BOARD C., 1972, “Cartographic communication,” {Cartographica: The International Journal for Geographic Information and Geovisualization} vol.18, n°2, p. 42-78.
About the map as a power symbol, the reference is the work of J.B. Harley :
HARLEY J. B., 1989, “Deconstructing the map,” {Cartographica: The International Journal for Geographic Information and Geovisualization} vol.26, n°2, p. 1-20.
About the nature of maps :
WOOD D., FELS, J., 2008, \textit{The Natures of Maps, Cartographic Constructions of the Natural World, }, Chicago, The University of Chicago Press.
For a general view about map perception and usage, i advise :
MACEACHREN A. M., 1995, {How Maps Work: Representation, Visualization and Design., }, New York, The Guilford Press.
Also, scholars like Barbara Petchenik and A. H. Robinson are key authors on the subject.
Finally, a very recent book about the epistemolgy of cartography is available :
Interesting subject !
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Thanks so much for your kindness.
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Hi dear, Tien Dat Pham
you can follow 
one or less                          ---  barren rock, sand or snow 
approximately 0.2 to 0.5   ---- shrubs or agriculture
approximately 0.6 to 0.9   ---Dense vegetation (Forest) 
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For a same digital elevation model (DEM), I applied different classifications. In the following figure, to the left is the outcome of natural breaks (Jenks 1967), while to the right is that of head/tail breaks (Jiang 2013). The right pattern revealed the underlying scaling pattern of far more low locations (or low value pixels) than high locations (or high value pixels). However, we have got used to the left pattern. What do you think?
Jenks G. F. (1967), The data model concept in statistical mapping, International Yearbook of Cartography, 7, 186-190.
Jiang B. (2013), Head/tail breaks: a new classification scheme for data with a heavy-tailed distribution, The Professional Geographer, 65(3), 482-494.
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Dear Gabriel Asato,
Many thanks for your comment that helps to bring the discussion in this thread at a high level. There are two kinds of beauty: one is triggered by surface colors and nice designs that is subjective, and the other exists in deep structure that is objective. I fully agree with you that some people like you are in favor of Tom Paterson's rendering, which looks beautiful and eye-catching. On  the other hand, a majority of people find (consciously or subconsciously) head/tail breaks-induced rendering has positive impacts on human well-being. The second kind of beauty can be effectively revealed by the head/tail breaks rather than conventional classification methods. I made this point clear in this paper:
Jiang B. and Sui D. (2014), A new kind of beauty out of the underlying scaling of geographic space, The Professional Geographer, 66(4), 676–686.
Even though there is no classification involved Tom Paterson's rendering, the color scale is still similar to those by conventional classification methods. Instead, I think the color scale should be similar to one by the head/tail breaks. Note: by color scale, I mean how color should be transitioned from one end to another (linearly, non-linearly, or arbitrarily).
More recently I developed a mathematical model of wholeness, with which one can learn why something is beautiful, but also how much something is beautiful.
Jiang B. (2015), Wholeness as a hierarchical graph to capture the nature of space, International Journal of Geographical Information Science, xx(x), xx-xx, Preprint: http://arxiv.org/abs/1502.03554
Clearly the right pattern is more beautiful than the left one. Benoit Mandelbrot referred to the left as cold and dry, while Christopher Alexander referred to the right as a living structure.
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I would like to use it as a base map for my own mapping purposes. Eventually, these maps would get published, therefore I need the base map to be open source. Thanks a lot! 
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Hi Gerrit,
did you had a look at OSM already? As far as I know, the Humanitatrian OpenStreetMap Project (http://hot.openstreetmap.org), helped to improve the Indonesian and in particular the Jakarta maps of OSM.
Here is a Blog post about flood response in Jakarta facilitating OSM data:
I can help with getting the OSM data into a GIS..
Cheers,
Christian
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A PhD student of mine is applying for a scholarship to stay in the US or Europe for 10 months. She wants to learn methods on calculating fractal dimensions in detail.
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I have re-defined fractal based on head/tail breaks; see this paper http://arxiv.org/ftp/arxiv/papers/1501/1501.03046.pdf