Science topic

Geomatics - Science topic

Geomatics is a synergism of various disciplines - Geographical Information System (GIS), computerised databases and applications, computer science, graphical processing, cartography, photogrammetry, statistics, remote sensing etc. The applications of Geomatics includes the real-world problems of management of natural and man-made environment and of the objects related to it. This would encompass the fields of natural resources management, resources planning and decision-making etc.
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Digital numbers of adjacent scan lines differ significantly, creating such a noticeable difference. All bands exhibit this problem, not just the RGB. Around 20% of all the images I downloaded for my study area (whether Sentinel 2 A or B) had this problem. I am not sure why.
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According to my research, this issue is due to a parallax effect between odd and even detectors (different detector footprints acquired from slightly different viewing angles) of the Sentinel 2 sensor. Also, this error isn't a result of atmospheric effects (so atmospheric correction processors won't help) but rather sun glint (the specular reflection of sunlight over water, which varies significantly with acquisition angles). There are some peer-reviewed methods of correcting sun glint in Sentinel 2 images (https://www.sciencedirect.com/science/article/pii/S0034425717304856), but they only “deglint” the images, leaving the stripes unchanged. So, I guess it is not fixable.
You can find more about this issue in the Sentinel-2 data quality report (https://sentinels.copernicus.eu/web/sentinel/user-guides/sentinel-2-msi/document-library).
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What research design is applicable to geodetic and Geomatics researches?
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Google Scholar is your friend.
See the "1.2 Applications of Geodesy" and "1.3.2 Trends in the Development of Geodesy" sections in http://ndl.ethernet.edu.et/bitstream/123456789/59034/1/697.pdf and the references to the 'bibliography: 'Exhaustive information about the trends of development is available in the literature (Schwarz 2000; Altamimi et al. 2011; Xu 2010; Xu 2012; Flechtner et al. 2010; Sideris 2009; Mertikas 2010; Drewes 2009; Pail et al. 2011; Plag and Pearlman 2009).'
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Answers to the question will greatly contribute to the acquisition of hardware and software for academic and research purposes.
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As already suggested I would use R that does not only offer several mapping options but a large suite of statistical packages. Keep in mind that if coding and programming is not exactly your thing and you need something more user-friendly, you could use the free Quantum GIS software which can be interfaced to a series of other applications, including R scripts, GRASS and many more to run propertary algorithms throug a GUI user-friendly interface
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Hello Everybody,
My objective is to model the stress-relief mechanism of a clayey meter scale experiment.
Please, share published material and your suggestions for such a small scale experiment.
Thanks  
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This is a good question.
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Right now I am studying GRAVSOFT for geoid modeling to use it in my thesis, I tried to read the manual but it was not explaining the GUI Python version (it is explaining the Fortran version), so that I am still confused to understand the software clearly. I would like to understand clearly which data I have to use for determination geoid modeling and the steps (step by step) of doing that using GRAVSOFT programs.
please provide me any documents or any files that can let me understand all the programs inside the GRAVSOFT interface specifically for creating geoid modeling.
Thanks in advance and your comments are appreciated
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Anas Sharafeldin Mohamed Osman GEOCOL and GEOGRID for gross-error detection.
Good luck
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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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Dear all!
I would like to suggest you take the survey "NSDI FOR YOU AND YOUR COUNTRY":
The results of this survey will help me to research the issues of the implementation of NSDI and get an overview of this policy.
I will be very grateful for your help, cooperation and sharing!
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Indeed, good start
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I put the Algorithm Sebal in Python language, can be opened in .txt, to estimate evapotranspiration in TM - Landsat 5 images, which works on Grass's G.dal platform, which is an extension of Qgis. Soon, I will make available those of Landsat 8.
Energy exchanges at the soil-plant-atmosphere interface, through the components of the radiation balance (Rn) and the heat fluxes in the soil (G), sensitive (H) and latent (LE), are essential for climate modeling and hydrological, which in turn affect the entire biosphere. Thus, having as objectives: (1) to estimate and compare the behavior of the energy balance components, using the SEBAL algorithm - Surface Energy Balance Algorithm for Land, in different types of land use and cover and (2) validation.
Please, when using, quote from: Lima, T.A.S .; (2020) Hydrogeological characterization and water use of a sector of sands, sandstones and gravel on the coast of Baixo Alentejo. 203 pp Master's Dissertation in the Geomatics course, University of Algarve.
Access:
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Thank you very much, it's a great job. When you have the same algorithm in R let me know.
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سلام،
مقاله شما در مجله اپلاید ژئوماتیک چاپ شده؟
تو سایت مجله پیداش نیست.
ممنون اگر ارجاعش رو به من بدید.
موفق باشید
توکلی
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سلام بر شما
ببخشید من پیام شما را تازه دیدم.
کدام مقاله؟
بنده مقاله ای در مجله ای که شما فرمودید ندارم.
پیروز و تندرست باشید
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.
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In attachment you may found the list of web-links towards around 30 PPP, post-processing programmes and on-line post-processing services.
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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 downloaded PCI Geomatic 2017 x64 with data and installed in my laptop Core I5 processor 1.6GH and 2.3 GHZ,8GB RAM and 1TB storage.
I installed with no problems,but while execution of the program ,it says the program closed and it closes every thing. what can I do?
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Such problem is related to an error in the installation process whether in the Program or License. Some missing files during installation make this problem. Try to reinstall it again after clean all files related to PCI.
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What is space? Is it what is conceived by Newton or by Leibniz? Both Newtonian and Leibnizian views of space are framed under the mechanistic thinking of Descartes back to the 17th century. Christopher Alexander in his life's work - The Nature of Order conceived and developed a brilliant new view of space: space is neither lifeless nor neutral, but a living structure capable of being more living or less living. This new view of space has some far-reaching implications. It implies that we make space or our built environment better, smarter, or more sustainable, or more livable, or more resilient. More importantly, it implies that goodness of space is a matter of fact rather than an opinion. In this paper, we attempted to provide empirical evidence space indeed has different degree of beauty or life:
By asking this question, what I really wanted to know how long it will take for us to adopt Alexandrine view of space. Benoit Mandelbrot said Euclidean shapes are cold and dry, but nature, traditional buildings and artifacts are full of living structures, as noted by Christopher Alexander.
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As an architect it's the biggest question
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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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HI, all
I want to get the program to extract Digital terrain models (DTM’s) or
Digital height models (DHM’s) for a certain area from Global Gravity Field Models related to Topography For example  dV_ELL_RET2012 
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In Mathcad writing
Elevation ==
Sum, for n = 1 to 2190,
for m = 1 to n, of
Coefficient C.m Cosine Lamda + Coefficient S.m Sine Lamda
is so easy, since the proper notation is available, but in Mathcad, we can *write*
d^n / d cos^n (theta) inline but it won't expand, even with Live Symbolics *on*.
So what is needed is to write it out of line, with Live Symbolics on, Evaluate Symbolically, and Paste the result. However, even at order 5, the result may be what Mathcad calls Huge. Too big. So we shall see.
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Hi everybody ,
i want to know about this journal hows it?
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The publisher of this journal is at Beall's list of predatory journals (https://beallslist.weebly.com/).
This suggests that it is more or less a pay to publish venue, with questionable (if not at all) peer review practices. Some argue that published in predatory journals might be harmful for your career.
In any case, there are decades of established and reputable peer reviewed journals so I would not see a reason for going there.
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As is well known and from theoretical proofs, proper weighting of the least squares solution of a leveling network is inversely proportion to the distances between the leveling points or the height difference between pairs of points. In other words, the uncertainties or the relative contribution of different observations in the least squares solution of the leveling networks are expressed in terms of distances. Sometimes the uncertainties of the existing control information are expressed in terms of their standard deviations, which were estimated from their previous dispersion or variance-covariance matrices. Although this type of expression or representation of uncertainties is very common, it makes the integration of the uncertainties of the existing control information to a new leveling network a non-trivial task. Now the question is:
What is the best weighting strategy for the observations and the control points? In some cases the control points will be introduced as fixed constraints, which can be viewed as some sort of a non optimal pseudo inverse solution.
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We recommend to use a combined stochastic model, i.e. an individual uncertainty (for each observation/waypoint) and a length-depending uncertainty, see Eq (24). The length of the survey line ignoresthe terrain profile and a levelling loop of e.g. 100 m in a horizontal terrain profile has the same weight as a levelling loop of 100 m in the mountains but different numbers of waypoints. If the number of waypoints differs from each other, the uncertainties cannot be the same.
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I am looking for a research about:
Comparison between the three dedicated gravity fields mapping mission, [CHAMP (1996), GRACE (2002) and GOCE (2009)], in geoid modeling (when using the satellite-only model related to these three mission)
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Dear, Dr. Basem
Many thanks for helping me and also for this answer
Can you help me to get more details about these three missions in a gravity field?
Regards
Abdel Rahim
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Conversion between different permanent tide systems involves either modifying one spherical harmonic coefficient or adding a zonally uniform correction to the geoid undulations.
 More information sees
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Recollection
Imagine the 3 gravity fields:
(1) the gravity field of the Earth, described in the rotating Earth-fixed coordinate
system, under the assumption that Moon and Sun do not exist ==> tide free gravity field model
(2) the gravity field of the Earth, described in the rotating Earth-fixed coordinate
system, plus the gravity fields of the Moon and the Sun averaged over a long time (which is called the permanent tidal effect), plus the effect of Earth's deformation, caused by Moon and Sun, on the gravity field (also averaged over time)   ==> mean tide gravity field model
(3) the gravity field of the Earth, described in the rotating Earth-fixed coordinate
system, without the gravity fields of the Moon and the Sun, but, with the indirect effect of Earth's deformation ==> zero tide gravity field model
The differences of these three gravity fields can be described (as the gravity
field itself) in terms of spherical harmonics. Strictly, these spherical harmonic series go up to infinity.
But, because the permanent (i.e. averaged over time) tidal effects change the gravity field only very globally, it turned out that it is sufficient to change only the coefficient C20, which describes the flattening of the equipotential surfaces of the gravity field.
This answer I received from Dr. Franz Barthelmes (Section 1.2: Global Geomonitoring and Gravity Field, Department 1: Geodesy and e-mail:    bar@gfz-potsdam.de)
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Usually, covariance functions are characterized by only a few parameters such as the  variance (Co) is scale factor and the correlation length.
How to determine the best parameters for representation Local covariance function
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Do you need the covariance function to be isotropic?  You usually do.  But you will discover that your experimentally determined covariance function is anything but isotropic.  What do you do then?
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Space debris include space junk, space waste and defunct objects in orbit around Earth. It includes spent rocket, old satellites and fragments and they pollute space. They usually can be tracked, but how about measuring their quantity and relating the values to threshold limits?
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One of the major problems is that items less than about 10-cm are hard to detect and/or track with terrestrial radar. What about space-based radar? There are satellites in orbit that could do this, should they be re-tasked..
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I am looking for a Python library or API that facilitates the creation of geo-spatial topologies and is able save them to a portable format, such as TopoJSON or GML.
The main goal is to save space in detailed polygonal topologies, with borders defined only once and shared among adjacent polygons.
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Hi Luis
I think GDAL [1] is your best option. You can see the specification in [2] and an example here [3]
Regards
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i need to find the value (on x-axis ) of the  first intersection point between two line by matlab
See attached for (data ,code and output )
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Dear Ricardo
Thanks for clarification
I found another solution where:the function "polyxpoly" used for Intersection points for lines or polygon edges
Many Thank
Regards
Abdel Rahim
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W0: defines the vertical datum of a height system ,Also it can be introduced as a primary parameter for the definition of a reference mean Earth ellipsoid (hence, level ellipsoid that best fits the geoid.)
So, How to estimation of W0 and best value?
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Dear Abdel Rahim, methods of estimating the geoid geopotential value W0, in addition to the previous and recent estimates have been described in some details in our paper "A conventional value for the geoid reference potential W0, doi:10.1007/s00190-016-0913-x" . This paper would satisfy your question. Nadim
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Bachelor of Science in Geomatics Final Year Project. 
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The easiest way using of software such as geosoft or modelvision. Also
b=a/((sin(c)+icos(c)sin(d+f))^2)
where
a is magnetic field in frequency domain (use of fourier transform)
c and d are Inclination and Declination angles, respectively.
f=atan(v/u)
where
v and u are wavenumber coordinate (find  subroutines At the end of the book)
b is reduction to pole anomaly
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Hi everyone, I have a doubt related to NDVI. I am comparing the NDVI image generated from Landsat TM, ETM+ and OLI sensor of December month. NDVI ranges which generated in image vary from year to year. So, is it feasible to compare these images with each other even the range of NDVI value is different?
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Chandrashekhar,
Yes, it is possible. However, be careful comparing across sensors of NDVI, particularly between TM/ETM and OLI. The NIR band in the OLI sensor has a slightly different range that could give different values, even for pseudo-invariant targets. The green band and red band are easier to compare between TM/ETM and OLI. For more perspective see:
There are a number of ways to compare NDVI over time. In addition to the suggestions above, you can also do pixel-wise linear trend analysis. For more information, please see: 
Good Luck!
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I am looking for a solution to transmit data while in Alaska and Greenland. Am leaning towards the Inmarsat iSatHub but coverage in Greenland may be difficult due to very low pointing angle required for geostationary satellites orbiting equator. Iridium GO is likely too slow. Any suggestions? 
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Thanks Valerio - unfortunately the Iridium Go is much too slow (2.4 kbps) for anything other than checking text email. that being said, iridium should be launching a next-gen satellite...so maybe that will provide a better solution!
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is there any methodology available to make a good clasification?. Thanks
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Hi all,
I would need to calculate the percentage of ice-free area in a certain radius around each of about 200 sampling points in Antarctica. I guess this would be a similar approach as to calculate vegetation cover etc.?
A long time ago I learned some GIS basics using Idrisi, but I haven't used it in 7-8 years and it was very basic. Now, I quite urgently need this data (2-3 weeks, but the sooner the better :) ).
Therefore, any advise is welcome to get me started.
I have the possibility to use ArcGIS and QGIS.
I came across Quantarctica for QGIS, which might provide the map. Any other sources for georeferenced maps of Antarctica?
I guess I can then plot the samples' coordinates, but I then have to manually delineate the ice-free regions by drawing polygons? Or are there layers available giving the ice-free surface or conversely, ice coverage, such that I would only need to detract this from the circle surface?
Can such an analysis be automated?
Sorry for these probably very basic questions. If you can provide me with a good crash-course tutorial (on GIS in general or a similar problem), that would be very welcome too :)
Thanks in advance!
Bjorn
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Hi Bjorn,
There are many ways of answering this question. And of course you can do this yourself. The internet has made our lives much easier nowadays. If you have ArcGIS or any other GIS software it can be done by just typing some keywords on the web. Moreover, there are thousands of online youtube videos that can assist you further. I have the following suggestion for you to give you a head start:
1. After you start ArcMap there is a possibility to add a Basemap Layer. See if you can find Antarctica base Maps.
2. Once you have the base map, you can import the coordinates of the sampling points from an excel sheet and convert it into a point shape file.
3. Draw a buffer around each point. This is an automatic process.
The rest I think you can figure out yourself. Check the links that I have attached. 
However, the questions that I have for you are these: Are you interested in any specific dates or have you collected any satellite imagery of your study area in Antarctica? The area which you are studying, are they covered by ice all the year round or do they change with seasons?
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I have the shapefiles from a map describing land occupation in Île de France. It's divided in 11 different classes (forests, buildings, houses, etc. - here's the metadata: http://www.iau-idf.fr/fileadmin/DataStorage/IauEtVous/CartesEtDonnees/cartesetdonnees/opendata/Mos2012_11_25m.html ) and I need to know what percentage of certain regions is covered by each class (how much of it is covered by houses, how much of it is covered by green spaces, etc.). 
I have the .shp, .dbf, .shx, .cpg, .txt, .sbn, .sbx, .xml, and .prj files, but I don't have a rasterized layer for this map. 
How can I use these files to find the percentages I need? I'm trying to use QGIS, but I've never used it before and I have no idea how to do it. 
Thank you!
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I presume you have another shapefile which represents the 'regions' within which you want to measure the cover of different classes from the shapefile you had uploaded.
If you want to rasterise the class shapefile to use zonal statistics, you can do this by going to the raster menu in QGIS and choosing the 'conversion > Rasterize' tool. Select the shapefile you want to convert to a raster, specify the column of the shapefile which contains the relevant values (code11 in your case), specify the resolution of the raster you want (25 in your case), and specify an output name for the raster. Then use the zonal statistics plugin as mentioned in Vahid's answer, along with the 'regions' shapefile.
If you want to work with vectors only, then what you will need to do is -
  1. dissolve the shapefile by classes - load your classes shapefile in QGIS, use the dissolve tool from the vector menu (vector > geoprocessing tools > dissolve). You will have to dissolve by class (in your case code11 in your shapefile). This will create a new shapefile where all polygons of a single class will be represented by a single (but multipart) polygon. Lets call this shapefile C1
  2. Load the shapefile with your 'regions' within which you want to measure cover of different classes. Measure the area of each region (vector > geometry tools > export/add geometry columns). This will add an area and perimeter column to the attribute table of the 'regions' shapefile. Lets call this shapefile R1
  3. Use the intersect tool (vector > geoprocessing tools > intersect) to intersect the dissolved classes shapefile (C1), with the 'regions' shapefile (R1). You will get an output shapefile, lets call it int1
  4. Calculate the area occupied by each class in each region in int1. Again, use the 'vector > geometry tools > export/add geometry columns' on int1.
  5. Create a blank column in int1 to store values for percent area - Open the attribute table of int1, click the 'toggle editing mode' button on the top of the table. Then click the 'add column' button and create a column where you will calculate the % area values. Specify a name for the column (e.g. per_area), choose type as 'decimal number', Width as 6 and precision as 3. Hit OK.
  6. Calculate % area in the blank column of int1 - In the attribute table for Int1 click on the 'field calculator' button. In the dialogue box that opens, select the 'update field' check box and select the blank column you created in step 5 above. Use the mathematical operators and the column names to calculate % area. These values should populate the blank column.
  7. Save - after the values have been calculated, click the 'save edits' button, followed by the 'toggle editing mode' button. You are done.
  8. You can then access the data either within QGIS through the attribute table OR open the dbf file in a spread sheet software of your choosing.
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Am working on a study to delineate the rain-fed and irrigated crops using Landsat data. Initially I have applied supervised classification based on the spectral signature difference.  But the results are not substantial.
Any alternative methods and suggestions might be helpful. 
Thanks in advance..
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Hello, use multi temporal landsat data (Dry season and Wet season) to achive your objective. Take two seasons images and classify them and combine the resuts using Knowledge based approch (i.e., decison tree approch). This approch is explained in the paper, but with respect to the forest, you have to twist the methodolgy for agriculture. Good luck!
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If you have worked or are working on a 'Shelf' project, as per UNCLOS, I will like to get in touch.
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What health and safety hazards are surveyors exposed to in the course of their work?   Please help with any research papers or article on this
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If you are talking about land surveying you would need to do a search in an occupational medicine database for studies.  Land surveyors are injured frequently as they have to move through a lot of rugged terrain and through dense and prickly vegetation.  Cuts, scrapes, infections, sprains and strains would all be common.  Since they have to cut the vegetation to clear sight lines, they can also be injured by their cutting tools.  Also, do not forget that they are constantly exposed to mosquitoes and ticks as they make contact with the vegetation.  And poison ivy and oak......
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Dear XiaoXing He,
YES, the main daily topic for Bernese software is estimation of the satellite orbits using the IGS staions in the CODE center (http://www.aiub.unibe.ch/content/research/satellite_geodesy/code___research/index_eng.html). The software provides the possibility to calculate the station coordinates in a file .CRD and the velocity in file .VEL, as well.
Example for coordinates
PPP_121830: Collecting results 21-APR-15 14:55
--------------------------------------------------------------------------------
LOCAL GEODETIC DATUM: IGb08 EPOCH: 2012-07-01 05:59:45
NUM STATION NAME X (M) Y (M) Z (M) FLAG
1 0384 4157307.00876 671172.07837 4774690.75540
2 0386 4126955.65484 669775.55002 4800826.89646
3 0391 4165864.35549 719747.77606 4760759.41483
4 0400 4179844.30978 667885.85324 4755620.48038
Example for velocity:
IGb08 velocities 09-OCT-2012
--------------------------------------------------------------------------------
LOCAL GEODETIC DATUM: IGb08
NUM STATION NAME VX (M/Y) VY (M/Y) VZ (M/Y) FLAG PLATE
1 ADE1 50109S001 -0.04085 0.00298 0.04851 Ib08 AUST
2 ADE2 50109S001 -0.04085 0.00298 0.04851 Ib08 AUST
3 AIRA 21742S001 -0.02581 -0.00734 -0.01507 Ib08
4 ALBH 40129M003 -0.01016 -0.00077 -0.00477 Ib08 NOAM
5 ALGO 40104M002 -0.01578 -0.00407 0.00425 Ib08 NOAM
Best Regards,
Ashraf
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Hi everyone,
I have a problem with the following: I have altered my raster .tif resolution in ArcGIS and again tried to convert it by ARC toolbox to ASCII (asc) format. So i confronted an error during this process with the name of "ERROR 010267: Syntax error in parsing grid expression. Failed to execute (RasterToASCII)." Can anyone give me a mind regarding this? How can i fix this?
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Dear Vijith
Thanks a lot for your resolutions and gratuities.
Cheers.
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Geomatics
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In this case the pixel size plays the biggest rule. for example pixe; size 30m it represent or cover an area equal (30m*30m) and one value will be assumed for this area, but if you used a bigger pixel size like 90m then each pixel will cover an area equal (90m*90m). 
So I think in this case maybe the catchment borders will be not the same exactly.
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We would like to prepare some examples of spectral signature of trees. It's for my geomatic course. Thanks in advance.
Marcelo
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Hi,
You can download sample data from the link 
Hope this will help you.
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is there a recent modeling method of geological interest to site, based on the most adptative criteria?
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Here in Nova Scotia (Canada) we recognize two types of Geoheritage: i) physical geoheritage (the classic geological sites, which are mainly a natural science feature); but also ii) cultural geoheritage sites (monuments, memorials, sacred sites, ancient mining sites) and these are both social and natural science-related in my opinion. Hope this helps!
John Calder
Could "geoheritage" be categorized as social science? - ResearchGate. Available from: https://www.researchgate.net/post/could_geoheritage_be_categorized_as_social_science [accessed Nov 23, 2015].
Thats information about type of geoheritage in Canada.
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How the Geomatics/Surveying could move up the value chain and learn how to play in the broader information environment?
 Do we need to adopt new business models, new service models, new ways of thinking, etc..
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Initially Land Surveyors, now Geomatician, are professionals that built the Digital Earth, a crucial infrastructure for the development of various important systems, such as Maps, GIS, DEM, and others. These in turn are systems that are widely used in the economic development of a nation.
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Why there is a shift between referenced toposheet and google earth images.
What may be reasons other than projections and scale.
Is there a shift in the positions when taking historical images wrt to acquisition dates. What are the reasons for it.
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Dear Vinod, 
Mr. Dierch reasons are correct. 
So if you have Erdas software you can solve this issues for 90%. 1St level we need to use, as per topomap projection(Keyboard method) after that you want to change set projection for Google earth image(Existing Viewer) or what ever it is. While we can reduce shifting both images.
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To my surprise many countries appear to report to the FAO every 5-years on forest extent statistics without using satellite Remote Sensing. I would appreciate to learn about countries that do use RS in their FRA. And for those countries that do not, about their motivation.
For an example of uncertainties in FRA forest extent statistics, please refer to my profile.
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Dear Hein,
The forest depletion (= deforestation + degradation) rate for Borneo is approx. -3%yr-1. This includes -2.2%yr-1 of deforestation. So, your Bolivian findings are consistent with Borneo data.
 We don't have illegal logging problem in Poland. Forests almost entirely belong to the state. The data for GFRA report are prepared based on data provided by the forest district officers and are reliable.
 Will you be interested to do a mutual project on forest dynamics? (kbecek"gmail.com)
 Here are my paper related to Borneo/Brunei.
 Best Regards,
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I am looking for a program to compute into Theoretical (Normal) Gravity (γ) value on the surface of the ellipsoid (WGS84) and Free-Air Anomaly (Δgf) with knowing Observed (or measured) Gravity (g) on the earth surface
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Hi, all
 i have excel program sheet based on Gravity definitions & anomaly computations (NGA document)
Download  file :- Gravity definitions & anomaly computations (NGA document)
and the latest version of World Geodetic System (WGS) 1984
see attached for excel sheet
Please testing the excel program sheet... when there are errors Contact with me
 Regards
Abdel Rahim
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I have some questions about Global Gravity Field Models (ICGFM).
Where How to Calculate Coefficients of this model? I.e. I need the program to compute spherical harmonic analysis of EGM model.
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Dear Eng, Ahmed
Thanks for adding your answer
this paper Failure during download
It can be sent to email (abd_roby87@yahoo.com)
Thanks
Abdel Rahim
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I just get a migration route from south China to Russia. Firstly, I  calculate  the length using arcgis with wgs1984 web mecator coordinate systerm. The length is 5800 km. Then I checked the route in Google Earth and the length is 4200 km. I am very confused how this happened.  Please tell me which number i should trust? Thanks!
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There are spherical or spheorid distance and cartesian distance options in GIS softwares. You can use first option practically. For more information and accuracy evaluations, you may check this link: http://www.ga.gov.au/scientific-topics/positioning-navigation/geodesy/geodetic-techniques/distance-calculation-algorithms
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I applied redness index to Landsat ETM+ in my study region located in the North western part of Algeria. I’ve got quite good results concerning Mediterranean red soil but I couldn’t understand why the vertisols are as bright as or even brighter than red soil in the redness index image.
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@Sachin Patil
The redness index is calculated as follow:
RI=〖(B3)〗^2/((B1)*〖(B2)〗^3 )
B1 : Reflectance of band 1 corresponding to the blue
B2 : Reflectance band 2 corresponding to green
B3 : Reflectance band 3 corresponding to red
of Landsat ETM+
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in the program GRAVSOFT , two Sub programmes
- Python Interface to “EMPCOV” (Program empirical covariance functions)
- Python Interface to “COVFIT” (Fit empirical functions to analytic models)
in figure below , what is empirical covariance functions and analytical covariance functions
I know how to be compute empirical covariance, but How can be obtained analytical covariance functions
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I have no idea what these words stand for.  They sound like names of some computer programs.  Possibly the people above are more knowledgeable, so you should listen to them.
Cheers,
PV
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EGM2008 can be viewed as an improvement to EGM2008. Now the question is: Does the modeling of the mathematical relationship between different global geoid models (say EGM2008 & EGM96) yield any kind of useful information?
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There are plenty of papers evaluating EGM2008 and showing that it presents an unprecedented resolution and accuracy.  Differences between a model and an improved one (such as EGM2008 and EGM96) have to be representative for these improvements introduced in the new model (e.g. higher spatial and temporal resolution). In other words, the information that you will get comparing the two models can be very likely inferred from the already known improvements introduced in the new one. Sometimes, such kind of differences can be used to model errors, e. g. for simulation purposes.
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We have an Infragram Point & Shoot camera (a modified Mobius Action Camera whose low-pass filter was replaced by a red filter; http://publiclab.org/wiki/infragram-point-shoot). For this modified camera, the "B" channel should be NIR. So, the "R" channel should be "red+NIR" and the "G" channel should be "green+NIR". We took a photo of leaves together with a Labsphere white panel. From the DN values of the three channels, how to calculate the reflectance values of NIR, red and green regions, respectively? How to calculate NDVI from the photo? Many thanks!
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Thanks a lot for your answer!
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Geometrical geoid modeling is a general problem to relate the GPS height to the quasi geoid. My question is: what are the criteria that guide the number of co-located points for problem modeling of the local geometrical geoid. Does it depends on the local topography?
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In my view, it primarily does not depend on the local topography, however it has some secondary influence. The local geoid can be represented by any number of points, but the values are exact only at those points. Interpolation/collocation algorithms can estimate the geoid position inbetween them and their accuracy is the function of the point density AND the geoid variation characteristic of the area. This latter one is somewhat affected by the topography. (The geoid is an 'weighted average' of the local gravity, which is itself a 'weighted average' of the topography and other factors.)
To turn to practice, in a hilly-low mountain area (e.g. our Hungarian regions), one point per 100 square kilometers provides a vertical accuracy in between the measured points cca. 2 centimeters, which is pretty good for almost all applications. In case of the Himalayas area, I'd expect some decimeters of ambiguity. However, don't forget that in high mountains, especially in steep slopes, the elevation difference between the geoid and the quasi geoid (the base levels of the orthometric and normal heights) can differ also in this range.
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This is required for my Ph. D research
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For Ganga basin, hydrological and hydro chemical work has been carried out by National Geophysical Research Institute, Hyderabad, India. Some work is already published. For litho log of Ganga basin as such no wave site is reported so far as very rightly mentioned by Deepak. However in this concerned above mentioned NGRI can be contacted and hope your problem may be solved up to some extent.
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Is there a program converted the EGM96 spherical harmonic coefficient set to their ellipsoidal harmonic coefficient counterpart?
I'm looking for a program to converted spherical harmonic coefficient (EGM96 or EGM2008) set to their ellipsoidal harmonic coefficient .
To develop this synthetic set of coefficients
Or how to get ellipsoidal harmonic coefficient of any EGM
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Dear Abdel
Please access to this link to get more information about EGM96 and EGM2008 http://earth-info.nga.mil/GandG/wgs84/gravitymod/index.html
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IndoorGML is new standard for indoor navigation network. I have building obejct in format obj, skp and I need create indoorGML. What application? Transform format? Thanks
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IndoorGML has a very rich semantic object model that will be hard to get from OBJ or Sketchup files. It is based on OGC GML and has structures more like IFC/Revit/CityGML than OBJ or SKP.
In any way, you can have a go with Safe Software's FME to attempt a conversion; use the schema-driven GML writer as a target. At least my version doesn't support IndoorGML directly yet.
An open source alternative might be to export your SKP models to KML/Collada and then use HALE (www.wetransform.to/products/hale) to transform to IndoorGML. This process would enable you to build up the semantic structure of IndoorGML.
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we will try to estimate wind speed and wind direction using SAR images, we used nest tool box, but it is limited fro C-band.
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You can use our open-source OpenWind package written in Python (https://github.com/nansencenter/openwind). Note, however, that wind direction is not estimated from the SAR images but we use apriori wind directions from models (default is ncep forecast). The master branch of the git repos is stable and depends on another package called Nansat (you'll find information on github). There is also an algorithm to estimate the wind field using a Bayesian minimalization scheme under the develop branch. When Sentinel-1 has the Doppler shift included in the data product, this can be used to also improve the wind directions. Hope it helps!
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We would like to know a detail step by step procedure for land suitability modeling for Apple in higher mountain range. 
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Hello,
You should try the multicriteria  evaluation using IDRISI software. It's a geographic supervised analysis to establish land cover suitability used for spatial location of predicted time transitions.
Nicolas
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Dears,
I'm trying to compute probable region of sunglint to use as a mask in the processing of remote sensing data. There are several methods for sunglint flaging using spectral characterizations, but I found only one reference to flag sunglint regions based on observation geometry (Mailhe et al. 2004, attached); that is more suitable for my application, but I'm having a hard time to perform the calculations.
One of the information required is the Earth-Sun unit vector for the epoch of observation; In the calculations of Mailhe et al. 2004, the J2000 Geocentric Celestial Inertial frame (GCI) is used for the computations. One possible source of such data is the NAIF SPICE toolkit (http://naif.jpl.nasa.gov/naif/); what I understood from the documentation is that the implemented J2000 reference frame actually represents the International Celestial Reference Frame (ICRF), that has its origin on the barycenter of the solar system, whereas the GCI J2000 has its origin on the barycenter of Earth. Nevertheless, the documentation also states that all calculations are relative to two selected bodies, with the origin playing a limited role (basically correction). In summary, I could not understand if the data from this source is appropriate for the calculations. The paper from Russel (1971, on the link) show an approximate formulation for GCI (but not J2000) with accuracy that should suffice for this application, but again I'm not sure if this is adequate. Perhaps it does not make much difference if the reference frame is kept constant through the computations?
The radial direction of the pixel center and the radial direction of the satellite must also be calculated. I followed the guidelines provided by Hapgood (1992, attached) to convert geodetic latitude, longitude and altitude from spherical to cartesian representation and them to GEI (which I understood is a synonym to GCI). I assume that this would be compatible with the Earth-Sun vector determination of Russel; nevertheless, the SPICE toolkit could also be used for these transformation to keep compatibility of reference frames if the SPICE Earth-Sun vector should be used.
Can anyone provide me with references and/suggestions about the sunglint geometry and Earth-Sun vector calculation?
Best regards,
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Diagram of my how I calculate the specular reflection angle, which is a prerequisite to calculating the glint angle:
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I have two raster files (.TIFF) with changes in temperature and precipitation for two reference periods. I was trying to use ArcGIS 10.2 to normalize the values from 0 to 1 in order to use it for my research, but everything I try results in error of a different kind. I tried to use:
1. Raster Calculator: (raster - mean) / stdv works, but the next step: ( raster - min(raster) ) / ( max(raster) - min(raster) ) results in error
2. Transformations tool from Geomorphometry & Gradient Metrics toolbox: I get this error every time:
RuntimeError: Object: Error in getting parameter as text
Failed to execute (transformations).
Coming from the agricultural sciences and hardly calling myself a GIS expert, I would appreciate any advice from you.
Thanks in advance.
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Dear Sachin,
No data values existed only when I imported the rasters in ArcMap. I believe the problem is related to xml file, which ArcMap creates for every raster and where it stores statistics among other information. When the same rasters are opened in QGIS, no data values disappear and all is well.
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I would like to calculate the correlation length using radar image. Can you tell me what the easiest procedure to calculate the correlation length of the radar images is?
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Thanks dear  Younes Khosravi and Jahangir Pachkam I will try it;
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My research is focusing about fusing SAR and optical imagery for improving land cover classification that specially maize crop. I'm not sure that ANN, SVM or DT technique, which one's better for agriculture. Do you have a idea?
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It depends on the dataset. No one can guarantee that SVM is better than ANN or ANN is better than DT. Setting parameters for each algorithm is also an important factor for improving classification accuracy. For most dataset, SVM and ANN provide higher classification accuracy than DT, but DT is the only classifier in these three which can identify important features from the model (the other two provide black-box model). You may try applying all these three classifiers to your data using WEKA and then compare the results.
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Is digitizing of map features completely dead?
For example, when and why do you still digitize features from a map?
It can be heads digitizing up from a scanned paper map (or image, or whatever) or using a traditional digitizing tablet. It can also just be digital and heads-up (i.e. you never had the paper map).
Do you ever still utilize manual feature digitization to create points, lines, or polygons?
I need this information for a statistical technique I am developing.
Addition.
Any VGIS examples?
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Dear Stuart,
in the archaeological domain this kind of operational approach is "still" very diffuse, due to enormous amount of archives material items, such as paper maps, radex and similar data recording supports, furthermore still too much employed in current field excavations and analysis.
Within our SITAR Project (see at http://sitar.archeoroma.beniculturali.it/ and some other resources at my RG profile), digitization activities represent the most important aspect for the first phase of our geo-data bank implementation, necessary for extracting above all polygonal archaeological features, altimetric points and related geospatial informations for mapping archaeological sites, monuments and complexes, and their fragmental partitions.
By the way, more generally such a necessary approach to data "distillation" implies some issues with regard to data heterogeneity, their completeness and final use and re-use. In this sense, this native heterogeneity generates, more or less deeply and distinctly, some questions on precision/completeness both at topographical and descriptive level, for old and also new data, motivating the implementation of semi-automated workflows in order to compare and re-align fragmentary different analogic source data.
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The estimation is conducted at global scale? Is that right to evaluate the simulation ability by comparing in-situ observations and grid-average means?Furthermore, is there some website to download the observation of leaf area index?
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Data of field campaigns usually are very valuable and not so easily distributed. As far as I know there is no a global web-site where you can download land in-situ measurements (such as LAI). Well if somebody knows it please inform me:-) However some in-situ LAI available among ESA Earth Observation Campaigns Data https://earth.esa.int/web/guest/campaigns. You have to register and apply for these data. Other possible source is NASA ORNL DAAC Land Validation Campaign Data http://daac.ornl.gov/validation.shtml. Here you have to just register. I don't sure that they distribute these data but maybe it's possible to find something as a result of MODIS Land Validation campaings http://landval.gsfc.nasa.gov/index.html
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Obviously MOIDS VI products are corrected (to some extents) for cloud shadows. But how about topographic shadows? If yes, any information on DEM and methodology used for corrections?
If no, to what extent do you think VIs (particularly NDVI) in C5 are affected by topography and illumination/viewing geometry? As far as the general appearance of the vegetation cover is concerned, my focus is not on "trees", but mostly on grass, shrubs, and subshrubs. Can I also have some suggestions from your own experiences with correcting topographic, viewing/illumination effects on NDVI?
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The MOD13 product is corrected for angular variations in observation and sun-target-sensor variations but not due to topography using a DEM (I believe). It is also important to note that there has occurred a significant degradation of the Terra MODIS sensor affecting VI data. See Wang et al. (2012) Remote Sens. Environ., 119.
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Regardless of the form or method used, should we take consider all biotic and abiotic factors of the physical environment or only the climat indicator (IC) and topography indicator (ITP) ?
Thank you for answering my question.
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Concerning your second question: as no/insufficient vegetation available for combustion (fuel load) inhibits the occurrence of a fire, I would at least include some quantitative measure of vegetation. Furthermore, humans are the major source of ignition in many ecosystems (and I could imagine in the Mediterraneans as well) - it thus makes sense to somehow account for those (e.g. proximity to roads, accessability,...) when determining fire risk or probability of ignition.  
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There are number of algorithms available in the literature for soil moisture down scaling especially derived from satellite data. Can these algorithms be used for soil nutrients also? what corrective actions should be taken in that case?
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Another paper I think that could be of some relevance is
"A spatially explicit methodology to quantify soil nutrient balances and their uncertainties at the national level" by J. P. Lesschen et al
Nutr Cycl Agroecosyst (2007) 78:111–131
DOI 10.1007/s10705-006-9078-y
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my data contains NA pixels
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Then it should be fairly easy to produce a RasterStack from your ncdf fields on which you can use raster::calc() to produce a RasterLayer of pixel averages. See help(calc)
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I need some full waveform experimental LIDAR data.
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Try here with ground truth data
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Cassini Soldner coordinate system has its origin at the intersection of equator and odd meridians. The odd meridians serve as central meridian for each two degree belt. The Reference ellipsoid used is Clarke 1858 and unit of measurement is the British Foot.
Coordinates in the Cassini system are converted to UTM (in this conversion Clarke 1880 is the  spheroid , Arc  1960  the Datum, Meters the units of measurement and UTM is the projection) Using one of the converted points as the base and staking out the rest within a radius of 5km in Kenya south of equator and zone 37S , errors increase as you tend away from the base. The staking out is done using a Geodetic GPS with appropriate settings
How can these errors be modeled? any research papers? 
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Dear Peter
The question is not so clear to me. First, UTM and Cassini coordinates are basically projected ellipsoidal coordinates (when h=0). The transformation of such coordinates are normally obtained by four transformation parameters and in very rare cases six transformation parameters when affinity factor is applied. Second, Seven parameter similarity transformation model (Bursa-Wolf model) is normally applied in the datum transformation of which UTM and Cassini are not.  Third, it is not clear whether the case presented (staking) is interpolation (within the network) or extrapolation (outside the network). Now lets say it is one of the two mentioned. Then I think , apart from the elaborate answer given by Sandi Berk, the  general variance propagation applies in this case (due to observation). Relatively larger errors would occur for the extrapolation case than the interpolation case. However,  variance would increase away from the reference point in both cases.
Kind regards,
Patroba.
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I want to estimate the soil loss for my study area but there are lots of confusion. USLE require rainfall erosivity factor, soil erodibility factor, topographic factor, crop management and conservation practice factor and I am unable in getting these factors.
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RUSLE has 6 factors in which R represents erosivity, ie the ability of the rainfall to erode the soil (which is the energy available with rainfall)
Other factors together called as erodibility, which is the resistance offered to the rainfall to withstand detachment of soil particles.
USLE/RUSLE estimates only the soil erosion.
Sediment yield is the quantum of soil comes out of the watershed from the eroded soil. This can be estimated through the relationship Sediment Yield = Sediment Delivery Ratio (SDR) x Soil Loss 
The estimation SDR is done through several emphirical equations (refer literature)
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I'm trying to produce a map of Greater Manchester indicating some specific site locations, but I understand that I need a geo-reference number of Manchester to be able to produce this map.
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You may try it in the google earth open source. For georeferencing you have to  collect minimum four known coordinates. The known coordinates information you can collect it from google earth by adding the landmarks option in your area. Good luck...
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This is the result I get - a distorted/asymetric scene with a lot of white "N/A" dots.
The funny thing is that for Radarsat-2 the results are clean and done, perfect.
Anyone know how to fix it, or an alternative software to perform an orthorectification?
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I have been trying to work with ScanSAR SSC data from Terrasar in NEST, and it does not work.  the bands are always kept separate and cannot be put together properly.
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I know that UAVs are one of the most important innovation of the last years in geomatic and I know that with these systems it is possible to obtain 3D models and orthoimages with high levels of detail and accuracy, but I know very few examples about the use of UAV in digital mapping, mainly to produce topographic maps.
Does anyone have information on this specific topic?
What could be the scale of the topographic maps?
What could be the size of the area to be surveyed?
What are the differences between fixed-wing and multi-rotor for these applications?
Many Thanks
Mauro
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Dear Prof. Brutto
I'm also new to this field of digital mapping through the use of UAVs. Nevertheless I've collected some useful papers which I thought would be good to share. Most of the questions which you raised are answered in these research papers. The first paper deals with the general introduction followed by specific applications of UAV in various domains. Please feel free to get in touch, I've some more papers. Couldn't upload all due to limitation of uploading only 10 files!
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I am looking for data description, links to data browsers including data collected by national institutions in other countries over the worlds.
What are their parameters?
How often they are collected usually?
Is there any official data browser?
For example, in Poland, ​​LIDAR of whole country with an average density of 4p/m2 and 12 p/m2 (for big cities) has been almost collected (90%). Link to the availability of data (DSM, DTM, LAS datasets) http://skorowidze.codgik.gov.pl/nmt/
Aerial photos are obtained every 2-3 years for whole country with a resolution of 10 cm (for big cities) and 25 cm or 50 cm for agricultural regions (depending on the size of real-estates) Link:
I'll be grateful for the assistance and support information about situation in your countries.
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In Italy at national level in 2008 a series of LIDAR measurements were done over almost 50% of the country focusing on populated areas, industrial areas and infrastructures. In 2011 the whole coastline was acquired.
Unfortunately the technical parameters are not easily to obtain. There is the National GeoPortal which includes the footprints of the LIDAR scenes acquired and all the derived products can be accessed both as CSW, WMS and ArcGIS service, but not the LIDAR scenes.
Furthermore the website, apart from the first pages, and the metadata are all in Italian, don't know how useful can be for you. However this is the link:
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Around 1991, Les. Worral has informed us that "more than 80% of data used by
managers and decision makers is related geographically". Back then, at the very early days of world wide web (WWW), with the absence of smartphones and Location Based Services (LBS) such news signified the important contribution of geograpfical thinking and relationships of data used by decision and policy makers. Today, after 23 years of major advances of internet with cloud computing and using real-time web-gis servers and geospatial modules, with availability of qualitative Open-Source software and web-services, is it possible to estimate the geographical relation of data used by managers and decision makers at a global scale? Is there existant such a research approach?
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Again it is a good research question. Although, it may be difficult to quantify the exact percentage of data being used by managers and decision makers that it is related geographically today without empirical studies. Please see this report.
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I want to understand the various methods used for 3D city modelling and their advantage, disadvantage.
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I agree with @Maurizio Teobaldelli but want to add: LIDAR would produce huge volume of data for which you must have very high computing machines. Moreover, its processing requires sound expertise and skills also commercial software like
Tera solid is expansive, as well.
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I am thinking of working on building a 3D model with the characteristics of urban materials using remote sensing data. Could you please suggest any approach or possible image combination for that? As this model needs 2d images with elevation, the challenge still is how to get the vertical objects' material types (such as walls).
Regards.
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Does the data have to be of a test-site? Or will you take stereo imagery from anywhere to test your theory. A few software suppliers such as Pix4D supply sample stereo imagery from UAVs, you can create 2.5D models of buildings and structures with those.
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Nowadays, lots of geospatial data is available on the World Wide Web that can be explored, exploited and consumed for free. Is this data accurate enough? Has anyone tested its horizontal/vertical accuracy? These are the questions which might be of interest to many of us.
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Freely available GIS dataset (crowd sourced GI) are created by volunteer and thus known as VGI. Quality assessment (accuracy,completeness etc) of crowd sourced GI and VGI is hot topic now a days . Many researchers and angled towards that area. Many research studies are available i.e
Girres, J. F., & Touya, G. (2010). Quality assessment of the French OpenStreetMap dataset. Transactions in GIS, 14(4), 435-459.
Ostermann, F. O., & Spinsanti, L. (2011, April). A conceptual workflow for automatically assessing the quality of volunteered geographic information for crisis management. In Proceedings of AGILE (Vol. 2011).
Grira, J., Bédard, Y., & Roche, S. (2010). Spatial data uncertainty in the VGI world: Going from consumer to producer. Geomatica, 64(1), 61-72.
Koukoletsos, T., Haklay, M., & Ellul, C. (2012). Assessing data completeness of VGI through an automated matching procedure for linear data. Transactions in GIS, 16(4), 477-498.
Goodchild, M. F., & Li, L. (2012). Assuring the quality of volunteered geographic information. Spatial statistics, 1, 110-120.
Ciepłuch, B., Mooney, P., & Winstanley, A. (2011). Building generic quality indicators for OpenStreetMap.
Bishr, M., & Janowicz, K. (2010, September). Can we trust information?-the case of volunteered geographic information. In Towards Digital Earth Search Discover and Share Geospatial Data Workshop at Future Internet Symposium, volume (Vol. 640).
Cooper, A. K., Coetzee, S., Kaczmarek, I., Kourie, D. G., Iwaniak, A., & Kubik, T. (2011). Challenges for quality in volunteered geographical information.
De Longueville, B., Ostländer, N., & Keskitalo, C. (2010). Addressing vagueness in Volunteered Geographic Information (VGI)–A case study. International Journal of Spatial Data Infrastructures Research, 5, 1725-0463.