Cartography - Science topic

Waiting for the answer

Even If you have little references, you can go on writing about Geocriticism.You'll come out with great results.Godspeed.

Maybe post your question in English so others can help you? If you want help translating your question you can always use Google translate, DeepL or some other translation website.

There are several online platforms and databases where you can find and download dust cartography data. Here are a few that you might find useful:

Dear Patrik Silva, it depends mostly on your specofic task and your aesthetic sensitivity. Feel free to use your own color scheme that most suitable to your goal. For example, use contrast colours if you need to unveil some thresholds, etc.

Hrvoje Heštera From my understanding of the limited information of the task, the 'sheets' are an irrelevant quantifier of the effort needed, whether the initial 'order' is 1, 10, or a hundred at a time, with various orders coming in over time. Basically, you are creating a 'pipeline' for an 'atlas' ( many arbitrary map sheets with a few standard scales ), automation with some additional QA/QC processes to verify compliance with the customers specifications. And really, the time you spend making four bespoke maps wold probably be the same as building the capability to generated thousands: https://gisgeography.com/how-to-create-qgis-atlas-mapbooks/

Not clear about the symbology situation, is that 20 layers, of which have sets of symbols ( like contour lines might have 3 different line type symbols, rivers 7, roads 6 etc. ). The vast amount of effort goes into dealing with the interactions between symbols, and obviously that can expand exponentially with the number of interacting symbols. This sometimes also necessitates a shadow / parallel GIS 'prepress' dataset to deal with areas of congestion like when you have a road, railroad, river, etc trying to occupy space on the paper at the same time. And really, some sort of revision system for taking in corrections and altering the cartography without changing the authoritative GIS data. You also can be completely screwed if your inputs have poor quality.

This all is really hard to communicate a pricing model to a customer who only knows 'map sheets'. If your dealing with a bureaucracy, the customer might not have choice, there may be a 300 year old billing protocol that only handles 'map sheets' ( been there ). If they have some flexibility there are ways stage the pricing model over the project lifetime that mitigate your economic risks over time - that's more detailed discussion. What's appropriate for a class project will evolve if it becomes a formal business.

Therefore, you have 20x20 = 400 control points. If you do georeferencing in Qgis, you can use all control points or some of them, like every 5 Km (16-points). During resampling, all pixels have coordinates in the ground system.

If you do not do georeferencing (no resampling), then you could calculate the coordinates of unknown pixels by interpolation. Suppose a pixel size a [m], then in one km, you have p = 1000/a pixels, and therefore known coordinates have the first(x1,y1) and the last(x2,y2) pixel. The slope angle between the first and last pixel is:

s = arc-tan[(x2-x1)/(y2-y1)]. Therefore, a pixel of a distance d from the first pixel has coordinates x = x1 + d.sin(s) and y = y1 +d.cos(s). You can do either row of column interpolation or both and take the average.

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.

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

Sorry, I don't have maps of Crimea

Dear Jens Kleb Antônio Carlos Pereira dos Santos Junior Omid Vakili Ch , 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

Topography is the study of the land features on the earth surface and cartography is the science and art mapping features

yes ,you can

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!

Hi

The UTM Geo Map software is so good for android.

Goodluck

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.

Unifed map style

See this article, It may help you.

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,

You may also try Cartogram Geoprocessing Tool. https://www.arcgis.com/home/item.html?id=d348614c97264ae19b0311019a5f2276

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.

In case someone is still looking for an answer. I found this video explaining how to do it.

Image of high-precision positioning and velocities maps are displayed digitally via using Generic Mapping Tools (GMT) often. For example, you can see maps like this in my article below.

Hi Dainius,

Additionally, those references may help you:

https://generalisation.icaci.org/book.html

https://www.amazon.com/Map-Generalization-Making-Knowledge-Representation/dp/0582080622

https://www.amazon.com/Scale-Spatial-Information-Analysis-Jingxiong/dp/1439829373

https://www.amazon.com/GIS-Generalization-Methodology-Practice-Gisdata/dp/0748403191

Best regards,

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."

See the integra in the link: http://www.geografia.fflch.usp.br/publicacoes/RDG/RDG_16/Roberto_Rosa.pdf

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.

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.

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.

Dear Ronak Jain and René Vázquez-Jiménez , Thank you all. I have got the answers.

Thank you @Julien Gloanec for your answer. Actually, we intend to know how to map the historical heritage, not the public health issues. Regards

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

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

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.

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.

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

I hope Sir this will be helpful links to solve your problem

https://youtu.be/c2ZfIRPdLwo      (ArcMap)

https://youtu.be/XutcR4KMk2k     (AutoCAD)

Here is the most up to date link to the position with details: http://www.earthworks-jobs.com/rsgis/ucd17071.html

Also see attached pdf for job description.

Follow the application instructions in: https://hrportal.ucd.ie/pls/corehrrecruit/erq_search_version_4.search_form

You need to register to apply for the position

Data-Interpolating Variational Analysis

Thank you sir. I will look into this.

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,

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.

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!

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:

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:

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

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

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

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,

Thank's all for aswners. I will try SDMTools!

Best,

Eduardo

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

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.

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/

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.

check/ validate your DEM first ,

try to calculate in degree slope

in using the k-means formula try to use the haversine distance instead of the Euclidean distance.

Hola Evan, you can request this information directly to BirdLife.

See this link: http://datazone.birdlife.org/site/requestgis

All the best,

Adrian

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

Gianmarco,

Some references providing the rationale and approach of GRASS r.walk and r.cost functions, and also a comparison with ArcGis Cost Path Analysis

Please contact to  Dr. Kazmi Geography Department UoK.

That would be exactly my answer, too.

if you can digitised contour and dem data u can use mapping in global mapper and surfer

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

Buenos días Manuel:

No tengo respuesta a tu pregunta. Quizás sepa algo José María Gentil.

Un abrazo

Thank-you!

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.

Do you know depthmapX tool??

maybe it' coukd be a good solution for your question

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.

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

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.

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?

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.    

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.

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.

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

Dear Essayas for your valuable explanation

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.