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.
Questions related to Geomatics
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.
Answers to the question will greatly contribute to the acquisition of hardware and software for academic and research purposes.
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.
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
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!
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.
Does anyone know how to indicate a free reference on free geotechnology? Which conceptually encompasses all free geotechnologies?
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?
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.
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
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
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.
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)
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
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
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?
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.
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 )
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?
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?
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?
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!
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.
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..
If you have worked or are working on a 'Shelf' project, as per UNCLOS, I will like to get in touch.
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
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?
is there a recent modeling method of geological interest to site, based on the most adptative criteria?
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..
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.
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.
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
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.
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!
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.
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
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?
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!
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?
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
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
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.
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?
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.
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?
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?
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?
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?
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?
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.
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?
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?
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.
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.
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?
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?
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.
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?
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).
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.