• Thorsten Reitz added an answer:
    How can I create IndoorGML format for my building object?

    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

    Thorsten Reitz · Esri R&D Center Zurich AG

    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 ( to transform to IndoorGML. This process would enable you to build up the semantic structure of IndoorGML.

  • Morten Wergeland Hansen added an answer:
    Does anyone know any software or toolbox use to estimate the wind direction from SAR images?

    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.

    Morten Wergeland Hansen · Nansen Environmental and Remote Sensing Center

    You can use our open-source OpenWind package written in Python ( 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!

  • Onur Satir added an answer:
    Methods for modeling apple landscape using remote sensing and GIS?

    We would like to know a detail step by step procedure for land suitability modeling for Apple in higher mountain range. 

    Onur Satir · Yuzuncu Yil University

    Use multicriteria approach combined with weight of evidence method based on current apple landscape location.

  • Brian Carcich added an answer:
    How to calculate sunglint regions from geometry?


    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 (; 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,

    Brian Carcich · Latchmoor Services, LLC

    You are very welcome, and thank you for the challenge.  I'm a bit of a SPICE evangelist and while I am not part of NAIF at JPL, the NAIF group at JPL is always looking to reach out and I like to support them (as they have supported me).  I think this particular problem would make an excellent case study for using SPICE, and I will probably bring it to their attention at some point.

    The funny part for me is that the code that solves the problem is usually just a few SPICE calls, but the steps to get to those calls is what takes up most of the code.


  • Jose Luis Ornelas-de Anda added an answer:
    Is the FAO Forest Resources Assessment in your country using satellite Remote Sensing?

    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.

    Jose Luis Ornelas-de Anda · Instituto Nacional de Estadística y Geografía

    Yes, there are some advantages and disadvantages with the visual interpretation.  On the positive side, we are able to identify and map vegetation types; not only for forests (temperate and tropical) but other plant formations as shrublands, grasslands, etc, as well as some succesional status characterization (primary, or secondary growth).  Some of the forest types are: pine, fir, pine-oak, oak-pine,  oak, cloud, juniper, etc (temperate), and among the tropical: high  evergreen tropical forest, medium semievergreen to low, deciduous (and some between them).  Basically the same classification system has been used through the whole versions.  Now, on the negative side: the subjective component in interpretation, and the different imagery sources; with varied characteristics and geometric properties. This makes hard to overlap precisely and so to compare different versions/dates . Another limitation is the source scale data, 1:250,000 it seems presently is not a detailed enough information.  On the other hand, the stats derived from each of the maps for the whole country seem consistent.  The LUCC is rather a vegetation classification system we use for Mexico, a crosswalk table is used to convert from the vegetation types to the categories in the FAO - LUCC.  The CONAFOR makes the conversions and area estimates, but they discuss with us the results before sending them to the FAO. As the responsible agency, they might consider some other issues in the final figures, but so far, the vegetation data sets from INEGI are the main base.  As mentioned in the previous post, eventually the land cover datasets obtained from the processing of Landsat - Geoeye imagery could be the source for the reports.  To have a more complete info, I can contact the CONAFOR.

  • Hayder Dibs added an answer:
    How can one normalize raster in ArcGIS?

    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.

    Hayder Dibs · Putra University, Malaysia

    also you can use ERDAS software 

  • Muntadher Aidi Shareef added an answer:
    How can we calculate the correlation length from images?

    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?

    Muntadher Aidi Shareef · ENSTA Bretagne

    Thanks dear  Younes Khosravi and Jahangir Pachkam I will try it;

  • Mustafa Üstüner added an answer:
    What classification technique is suitable with image fusion (SAR and Optical imagery) for improving land cover classification?

    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?

    Mustafa Üstüner · Yildiz Technical University

    Please see the article below. 

    Björn Waske, Matthias Braun, Classifier ensembles for land cover mapping using multitemporal SAR imagery, ISPRS Journal of Photogrammetry and Remote Sensing, Volume 64, Issue 5, September 2009, Pages 450-457, ISSN 0924-2716,

  • François-Nicolas Robinne added an answer:
    Using remote sensing tool, what is the simplest method to use for studying the forest fire risk in a mediterranean region?

    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.

    François-Nicolas Robinne · University of Alberta

    Allessandro is right, niche modelling using the maximum of entropy approach has proven its usefulness. There are several software which implement it, like MAXENT or ModEco.

    This paper might be of some interest as well: "Spatial variability in wildfire probability across the western United States", Parisien & al

  • Andreas Paul added an answer:
    In what real-world examples do users still digitize features from a map?

    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.


    Any VGIS examples?

  • Fábio Marcelo Breunig added an answer:
    Are MODIS C5 Vegetation Index products corrected for topographic shadows?

    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?

    Fábio Marcelo Breunig · Universidade Federal de Santa Maria


    The tpographic shadows are not addressed, as well directional effects.

  • Maxim Chernetskiy added an answer:
    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?

    Maxim Chernetskiy · Friedrich-Schiller-University Jena

    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 You have to register and apply for these data. Other possible source is NASA ORNL DAAC Land Validation Campaign Data 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

  • 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

    hey bogdan, can you refer me to the article i have a look at it

  • Ranendu Ghosh added an answer:
    Can anyone suggest a suitable algorithm for downscaling soil nutrients?

    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?

    Ranendu Ghosh · Dhirubhai Ambani Institute of Information and Communication Technology

    Thank you Dr Jayaraman. I will go through the papers.

  • Hayder Dibs added an answer:
    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 

    Hayder Dibs · Putra University, Malaysia

    Dear Kazimierz and Peter thank you very much for your cooperation.

    regarding to radar image I see it is quite ok, In contrast to the paper that mentioned by Mr. Kazimierz I already had this paper> I am very interest to radiometric correction and I already develop new automatic technique to generate pseudo invariant feature to involve in normalizing, However, I always looking to other researchers idea,

    I very grateful from both of you

    my regards 

  • 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)

  • 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 · GeoNumerics

    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

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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