• Tim Appelhans added an answer:
    How I can create in R an average image from a list of NCDF data ?

    my data contains NA pixels

    Tim Appelhans · Philipps-Universität Marburg

    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)

  • Hayder Dibs asked a question:
    What is the best algorithm to perform the radiometric normalization for tropical region satellite images?

    relative radiometric normalization of tropical regions satellite images, especially these regions almost covert with tropical forest 

  • Xiaolu Ling asked a question:
    How can I estimate the simulated global Leaf Area Index by CLM4CN? Except for the satellite data, is there some in-situ observations?

    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?

  • Abdullah Ozcan added an answer:
    Can anyone tell me where I can download the free full waveform experimental LIDAR data?
    I need some full waveform experimental LIDAR data.
    Abdullah Ozcan · Yeditepe University

    Try here with ground truth data

  • Syed Adnan added an answer:
    How to make soil Maps from point data?
    I have 100+ point data of soil type, for example at point x soil is "clay", at point y soil is "clay-sand", at point z soil is "sand" and so on. Now i want to generate soil map/surfaces. Kindly help me if anyone has some solution, suggestions or free software.
    Syed Adnan · National University of Science and Technology

    Dear Rasha,

    I got soil map from soil survey of Pakistan, digitized and converted it to raster which was required for my study. So its the good option to get it from you soil survey dept. ;-)

  • Peter Mwangi Macharia added an answer:
    How can I deal with modelling Cassini to Utm Conversion Errors?

    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? 

    Peter Mwangi Macharia · Jomo Kenyatta University of Agriculture and Technology

    Dear Andrea De Tommasi

    From the link given ( its gives an abstract of the research carried out, the link provided to get the entire research in a pdf format is broken. 

  • Sudheerkumar Yamsani added an answer:
    How can I calculate sediment yield using Universal Soil Loss Equation (USLE)? and what input data require in using USLE?
    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.
    Sudheerkumar Yamsani · Indian Institute of Technology Guwahati

    Can i know your point of application?

    What is the area of consideration?

  • SureshKumar M added an answer:
    Does anyone know the Geo-reference number for Greater Manchester or England?

    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.

    SureshKumar M · Sri Chandrasekharendra Saraswathi Viswa Mahavidyalaya University

    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...

  • Pere Molina added an answer:
    Does anyone have examples of works, researches, or publications on digital mapping from UAV?

    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


    Pere Molina · CTTC Catalan Telecommunications Technology Centre

    Dear Mauro,

    Dr. Ismael Colomina and I co-authored a paper which entailed a comprehensive review of the uses of Unmanned Aerial Systems (UAS) in Photogrammetry and Remote Sensing (PaRS), covering history, architectures, sensors, regulations and requirements for PaRS.

    The paper was published by the International Society for Photogrammetry and Remote Sensing on June 2014, being thus a pretty recent large-scale survey of its kind.

    Please, find this open-access publication in the attached link. Enjoy! :)

  • Filippo Salustri added an answer:
    Does it make sense to assess uncertainty in climate change impact projections?
    It is now widely admitted that climate change impacts on water resources are occurring and are expected to amplify in the future. However, these impacts are highly uncertain and usually scientist and decision makers prefer to have a quantitative assessment of these associated uncertainties. How can we assess future uncertainty related to climate change in the absence of observations? Then, how can decision makers consider these uncertainties in their future plan management of water resources for instance?
  • Napoleon Eduardo Cornejo added an answer:
    Which software is more suitable to perform a orthorectification on TerraSAR-X ScanSAR MGD imagery? I'm using PCI and getting really bad results.
    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?
    Napoleon Eduardo Cornejo · Science and Technology Corporation

    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.

  • Joe Mccollum added an answer:
    How can space debris be measured aside from just tracking them?
    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?
    Joe Mccollum · US Forest Service

    Putting a reentry motor on every space shuttle tile that flicks off would not be practical.

  • Andrei Mîrț added an answer:
    Do you have information about national projects of LIDAR and photogrammetric missions in your country?
    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)
    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.
    Andrei Mîrț · Wageningen University

    For the Netherlands, there is AHN.

    You can find all information and download links here:

    Though it's easier to access the data through or through their qgis plugin also called pdok viewer.

    As far as I know they redo it every three years.

  • Ana-Maria Ciobotaru added an answer:
    Has anyone checked the accuracy of freely available datasets on the web?
    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.
    Ana-Maria Ciobotaru · University of Bucharest
    I have also the same question and I have put here on RG. That was abou the data of lans use - land corine - CLC.
  • Ireneusz Baran added an answer:
    What are the methods for 3D City Modeling and which one is best?
    I want to understand the various methods used for 3D city modelling and their advantage, disadvantage.
  • Ismail Önden added an answer:
    What is the persentage of data used by managers and decision makers that it is related geographically today at global scale?
    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?
    Ismail Önden · Okan Universitesi
    when i read the question, i remembered the tobler's law: "everything is related to everything else but near things are more related than distant things".

    i remember the recent publications for empirical proofs for the first law of the geography. these researchs might help to find answers of your question.
  • Jasim Ali added an answer:
    How can we get 3D urban surface materials by remote sensing?
    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).
    Jasim Ali · University of Nottingham
    no it does not, I need to build a 3D or 2.5D for a hole city
  • Dieu Tien Bui added an answer:
    What are the best iPad/Android Apps for GPS tracking and geology?
    Tell me about the apps you can’t live without
    Dieu Tien Bui · Telemark University College
    Could try iGeoTrans
  • Peter Mwangi Macharia added an answer:
    What is the minimum acceptable sample size in AHP when you have 13 variables under consideration?
    I have a range of experts but I am not sure how many questionnaires I should run.
    Peter Mwangi Macharia · Jomo Kenyatta University of Agriculture and Technology
    Elaborate the likert scale
  • Prabu Dheenathayalan added an answer:
    What is the standard difference between DTM, DSM and DEM especially with respect to the fast-changing geospatial semantics?
    These three terminologies can be confusing. Please shed more light.
  • Kris Nackaerts added an answer:
    How can I import and process MODIS EVI Data from MODIS Data set (8 day period combined product ) using open source GIS softwares?
    The data is available in HDF format.
    Kris Nackaerts · Flemish Institute for Technological Research
    A nice tool for MODIS data =
  • Paul Ouma added an answer:
    Can anybody provide a list of all the available software packages for Precise Point Positioning (PPP) technology?
    Paul Ouma · Jomo Kenyatta University of Agriculture and Technology
    Try this
    RTKLIB, its an opensource software and easy to use
  • Alberto Blanco added an answer:
    Do you have any suggestions/comments on the new online version of the Habsburg Second Military Survey (1806-1869) maps?
    Our project about to geo-referring and web publishing of the whole Habsburg Second Military Survey, covering Austria, Hungary, Czech Rep, Slovakia, Slovenia, Croatia, parts of Ukraine, Poland, Romania, Italy, Montenegro and Serbia is finished, result is here:
    We'd be happy to hear any suggestions for further improvement of the page and the database, which is open to the scientific community.
    Alberto Blanco · University of Alcalá
    Balazs, this is exactly what I was asking. I considered very important trying to develop a lot of environmental studies (environment because is my theme) using the maps as reference. We are doing something "similar" in the Madrid Region in Spain.

  • Huang Jinlong added an answer:
    Does anyone have the erdas or envi model for the geostatistical neighborhood similar pixel interpolator?
    I am comparing methods for data filling for Landsat ETM+ SLC-off
    Huang Jinlong · Nanjing University
    You can download it from here -->
  • Abhilasha Kumari added an answer:
    In ERDAS how can we convert the classified images into the grid?
    For plotting spatial metrics we have to classify the temporal images and then we have to convert it into grid and then input it into fragstat tool. But I am not getting how to convert the classified images into the grid in Erdas or any other software. Please suggest how to convert the classified images into the grid?
    Thank you all. Really i try in erdas and arcgis also, it worked..thanks all
  • Richard Gloaguen added an answer:
    How can you use rapid eye images and landsat in biomass study when the rapid eye images only cover certain areas of your whole study area?
    The high resolution rapid eye images cover 4 villages of a whole district which is the study area.
  • Wendy M Griffiths added an answer:
    What are the best institutions to study Remote Sensing for pasture and natural grasslands worldwide?
    I am looking for a place to send a student to spend about six months developing a research project in this thematic area
    Wendy M Griffiths · DairyNZ
    If the student wants an experience downunder - Ian Yule at Massey University, NZ
  • Cristina Radnea added an answer:
    How can one orthorectify LISS-4 MX data in Erdas Imagine?
    To orthorectify any image RPC file is needed. How to obtain RPC file for LISS-4 data?
    Cristina Radnea · National Research and Development Institute for Soil Science, Agrochemistry and Environmental Protection
    I don't think it will work, but try to put this question to the data provider; he is from your country, isn't he ?
  • Richard James Telford added an answer:
    Fitting variogram model with NLS in R
    I tried to compare the result obtained by fitting the spherical variogram model using fit.variogram and nls functions. The large difference in the results is a great concern for me knowing that the two functions use Weighted Least Squares (WLS) approach for estimating parameters. The steps taken are as follows: ## Fit empirical semivariogram using gstat empvar<-variogram(yield ~ 1,canmod.sp,cutoff= 400,width = 25, Cressie=TRUE) # Fitting Spherical variogram model to sample variogram sph.var<- vgm(psill =130, model = "Sph", range = 65, nugget = 180) sph.mod<-fit.variogram(empvar, model = sph.var) print(sph.mod) The result obtain from fitting the spherical model to sample variogram is sph.mod model psill range 1 Nug 230.917736411 0.0000000000 2 Sph 108.323055319 87.6889385431 The non-linear least squares (NLS) approach use by default s Gauss-newton algorithm in an iterative search process. I used the initial values obtained from the empirical variogram above (psill=130, range=65, and nugget=180) as starting values for the iterative procedure. ## Define Spherical Variogram functions for NLS sph.vgram <- function(dist, range, psill, nugget){ dist <- dist/range nugget + psill*ifelse(dist < 1, (1.5 * dist - 0.5 * dist^3),1) } ## Fitting spherical with NLS fit.var <- nls(gamma~sph.vgram(dist,range,psill,nugget),data = empvar, start=list(psill=130, range=65, nugget=180),trace=T) The result obtained from the nls fitting is Nonlinear regression model model: gamma ~ sph.vgram(dist, range, psill, nugget) data: empvar psill range nugget 90.7071423 342.1025007 278.9542178 residual sum-of-squares: 1140.67875 Number of iterations to convergence: 18 Achieved convergence tolerance: 9.79837651e-06 Could anyone explain why large difference in the two result? Is the R script for fitting the NLS right? I am worried for having such disparity. Thanks while looking forward to reading your suggestion, comments and advice. Moshood.
    Richard James Telford · University of Bergen
    fit.variogram is weighted by the number of observations in each distance class - see help file for details. That might explain the difference between the fit.variogram results and the nls results.
  • Natheer Alabsi added an answer:
    What GPS mapping software do you use?
    I'm looking for the best in class software solutions with which you can do the following:
    a) define a map with territorial units (e.g. district, region, country, etc.),
    b) import GPS coordinates and another associated variable (e.g. self-reported well-being),
    c) calculate the average per territorial unit of these associated variable values,
    d) colour-code the average values from min to max,
    e) export the map.
    Natheer Alabsi · The University of Tokyo
    you can try Trimble GPS Analyst extension for ArcGIS

About Geomatics

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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