Geographic Information Systems

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For questions about Digital Elevation Models (DEM), Digital Terrain Models (DTM) and Digital Surface Models (DSM)

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Problem with CRS metadata for UK Environment Agency LiDAR DSM tiles?

I have downloaded some LIDAR DSM composite tiles from https://environment.data.gov.uk/DefraDataDownload/?Mode=survey and opened them in QGIS 3.6 with project CRS set to OSGB 1936 (EPSG:27700). ...
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1answer
269 views

Resample/Increase the resolution of Digital Elevation Model by QGIS [closed]

I have a DEM of 5m pixel. I wonder is it okay to convert it to 2m pixel? How to do that using QGIS? And what would happen to the original data, I mean the accuracy? Would it be reliable?
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1answer
16 views

CGIAR DEM converted to XYZ consists of Nodata only

I have a 30-by-30 tile from http://srtm.csi.cgiar.org/srtmdata/ Later I pre-process as outlined in the previous question CGIAR DEM + gdalwarp -- projection to Cartesian is not happening (see the ...
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20 views

CGIAR DEM + gdalwarp — projection to Cartesian is not happening

I have downloaded a 30-by-30 tile from http://srtm.csi.cgiar.org/srtmdata/ Then gdalinfo on the obtained single *.tif-file would yield Driver: GTiff/GeoTIFF Files: cut_n30e000.tif ...
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1answer
44 views

UTM Projection of DEM-data with gdalwarp

I have downloaded a certain tile from https://www.eorc.jaxa.jp/ALOS/en/aw3d30/data/index.htm, and after the requisite logistics (unzipping, putting all *.AVE_DSM.tif files into a single folder), I ...
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74 views

Howerive vector stream network from a DEM using D-Infinity Flow Direction algorithm?

I have been working with a 1m LiDAR derived DEM to create a vector stream network. Using the D8 flow direction, D8 flow accumulation, and a specified threshold, I was able to create a vector stream ...
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8 views

Getting 3D polygon to reach next isoline using ArcScene 10.5

I have a flood innundation polygon and the DEM used to generate it. I've added the Z coordinates for the innundation shapefile from the DEM, but I need to get it to reach the next isoline which ...
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60 views

Mars DEM: Interpretation

I have processed the *.tif-file from https://astrogeology.usgs.gov/search/map/Mars/GlobalSurveyor/MOLA/Mars_MGS_MOLA_DEM_mosaic_global_463m as gdalbuildvrt mars.vrt <filename>, and now gdalinfo ...
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1answer
108 views

GDAL: gdallocationinfo of CGIAR mosaic elevation data

I have downloaded tiles from http://srtm.csi.cgiar.org/srtmdata/ and unpacked the *.zip files into a directory. Then I ran, as has been suggested here: CGIAR SRTM to xyz using GRASS GIS, with ...
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52 views

How to open G.L.O.B.E. DEM files from NOAA

I need to open a free GLOBE DEM. I have downloaded some tiles from: https://www.ngdc.noaa.gov/mgg/topo/gltiles.html, but I don't know which software should I use in order to open those files. Is ...
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1answer
23 views

How to open a .dem file properly?

I have this DEM file downloaded from the internet. It's a text-formatted file and it looks like this: 1440 720 30 -9999 450 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -...
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1answer
163 views

QGIS 3.4 Stream delineation problem, lines running too far into ocean

I am using QGIS 3.4.4 Madeira version trying to delineate the stream and catchment areas of a small Bay in Honduras based on the technique of Hanz van der kwast tutorial "Stream and Catchment ...
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77 views

Extracting Ridges from DEM ALOS

I'm currently working on a forestry project for my thesis. It consists of the optimization of skids tracks planification using ALOS images. To this end I would like to extract obstacles such as steep ...
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1answer
37 views

Slope is not consistent with the elevation of DEM and seems to be incorrect

I have a DEM image which shows the elevation is from approx. 81 to 103. I expected the slope should be 0-22m. However, the result from DEM-Terrain Model-Slope is from 2.5 to 13.2. Anyone knows why?
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1answer
36 views

Adding height to dam in ArcGIS Desktop?

I'm having issues with flow direction in a reservoir heading in both directions. To try and correct this I think I need to add height to the portion of the DEM that currently represents the dam to ...
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29 views

Fixing sharp edges between GeoTIFF tiles? [duplicate]

I've downloaded a couple SRTM DEMS from http://srtm.csi.cgiar.org and when I load some of them into QGIS, there is a noticeable edge between 2 of the tiles (see image). Why does it happen? These are ...
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86 views

GdalDEM slope error in Jupyter

I try to calculate slope data. This is the DEM source https://www.earthenv.org/DEM Firstly, I translate data with gdal.Warp according to image UTM zone. Original image .bil extension so first I ...
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1answer
31 views

Applying same symbology to different DEMs?

I am using ArcScene and ran into this problem where I downloaded a couple of neighboring/bordering DEMs(in BIL format), imported them into the scene (as separate entities) and applied Base Heights so ...
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2answers
188 views

Raster antialiasing

I am looking for a way to antialias integer DEM data (hgt file) to float GeoTIFF. That way I want to avoid gdaldem hillshade artefact lines which you can see in this picture: I don't want to blur ...
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168 views

QGIS Exporting Layout as Blank PDF?

I am trying to export my map layout in QGIS3.4.5 on OSX 10.14. I've made the layout look exactly how I want it to look, but whenever I export to PDF, the PDF file is just a blank white page. The ...
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1answer
115 views

Mirrored Contours from DEM in QGIS

I am trying to create contours from a DEM in QGIS 3.4. I used the GDAL raster extraction contour tool. The contours are drawn correctly, but they are mirrored along the north line of the DEM (see ...
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1answer
96 views

Find higher elevation (10m) perpendicular point from stream network at regular interval

I have a stream network and for that network, I want to find the points at regular intervals which lie at 10m distance perpendicular from the stream.The final goal is to find the buffer of that 10m ...
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1answer
78 views

sampling error using gdalwarp on a subsetted VRT?

I am currently trying to prepare an SRTM subset including height conversion from EGM96 to WGS84 using gdalwarp. I encountered some strange shifts in part of the image. Here is a reproducible example: ...
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0answers
169 views

Increasing zoom level in 3D View QGIS Desktop?

I would like to increase the zoom level for my mosaic raster image in the 3D View of QGIS Desktop 3.4.4. I made a mosaic out of four raster images downloaded through the STRM-plugin for DEM data. ...
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24 views

How do I compare multiple years worth of geomorph changes in a river while drawing one profile line?

I have many years worth of DEMs of a river I'm studying. I'm very, very new to ArcGIS (think one intro class), and learned how to use the 3D analyst tool. What I'd like to be able to do, is to draw ...
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165 views

Easy way in PyQGIS to convert a distance from meters to coordinates?

I am attempting to clip DEM rasters (USGS, in WGS 84) into a set of tiles measuring 2.56km on a side, in QGIS, using python. So far, it appears that gdal_translate is working for me, using a ...
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1answer
55 views

Generating DEM Generation in LPS?

I have a Cartosat 2.5 m Imagery and Block files along with DSM Data. I wanted to generate DEM using Leica Photogrammetry Suite Software. Does anyone know the steps of generating same? I have to edit ...
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1answer
50 views

FME Surface Modeller “minimum number of points”

IN FME workbench 2016.1 I want to create a DEM from Multipatch-geometry contained in a geodatabase, for doing that I thought using the SurfaceModeller could work, where in SurfaceModeller I group the ...
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1answer
34 views

Converting IMG to BIL/HRD/BLW?

I'm trying to convert IMG data from USGS's 1/9 arc second DEM to something that Pathloss 5 can read. Is there a way to do so?
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2answers
96 views

Visibility analysis with mask for non visible areas?

I have LiDAR data and I've made a Digital Surface Model (DSM): I've made a visibility analysis for 3 buildings with this model: My goal is to know from where the buildings are visible, not what do ...
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1answer
59 views

Extract height from DTM into attribute table of point layer [duplicate]

I am using ArcGIS Desktop 10.4 I have an empty point layer (100 random points) and a dtm. I was wondering how I would go about to get the height from the dtm underneath each point into the points ...
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1answer
63 views

Highest point from DEM

I generated the next DEM abd Orthomosaic and I am interested in extract the highest point of each building, is there any workwflow that I could implement in QGIS or SAGAGIS
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42 views

Filling NoData around bridges in DEM

Is it possible to fill no data around bridges without pixels blurriness (see picture). I use Elevation Void fill function, also tried in qgis No data filling and Grassgis r.fillnulls. I know, that I ...
2
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1answer
100 views

Translating vector by raster DEM data in QGIS?

I'm trying to follow the set of instructions here: https://twitter.com/imhere_asia/status/1023055838787690496 [EDIT] Pasting the instructions here for reference so people can avoid twitter. ...
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0answers
37 views

Channel network from high resolution DEM for flat areas

I'm working on channel network extraction from a LiDAR DEM (square grid max resolution 0,25 cm), and my area of study is vary flat with some part below the sea level. I applied the classical valley ...
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0answers
78 views

Difference between DEM raster in QGIS 2.18 and 3.4.4 [duplicate]

I came across a really strange problem. Untill today i always worked in QGIS 2.18. Now i wanted to upgraded to 3.4.4 ( it was already downloaded but hadn't used it yet) When opening my QGIS ...
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0answers
79 views

Creating 3D Local Scene using pointcloud, DSM, and orthomosaic from Drone in ArcGIS Pro?

I am trying to create a local 3D scene in ArcGIS Pro and display data fro drone flights. I have the orthomosaic from the flight as a .tif, the Digital Surface Model as a .tif, and my pointcloud from ...
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0answers
70 views

Problems with DEM exporting after Elevation Void Fill function use

I filled nodata values in DEM by Elevation Void Fill function, everything was ok, but when I exported it, the raster looks different (see picture above), how can I solve this problem? I also tried r....
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0answers
98 views

Importing several LiDAR (.las) files in GRASS using v.in.lidar?

I'm building a DEM of a terrain in GRASS and have 48 LiDAR (.las) files. I know I can do this by using r.in.lidar (including the list of files as a .txt) and then r.fillnulls However, I want to ...
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21 views

Assessing mapping accuracy of a DEM with different resolutions

I am mapping conical shaped depressions on the seafloor and would like to know at what resolution of the DEM is my mapping accuracy affected by. For example if I have a DEM of 7 metres, what does the ...
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3answers
475 views

Clip tool in ArcGIS Pro not working?

I'm trying to clip "Terrain" raster I downloaded from the portal (https://www.arcgis.com/home/item.html?id=58a541efc59545e6b7137f961d7de883) in the shape of a polygon (a country's boundaries) by using ...
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1answer
151 views

QGIS 3.4 and DEMto3D 2.3 Scaling Error

I'm having a scaling problem when using DEMto3D and extracting STL's for later manipulation. I have a merged TIFF file for Australia and am attempting to extract models of each state so I can print ...
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69 views

QGIS Display Attributes as Z Value for Point Shapefile?

I would like to create a state map that displays a 3D bar chart for each of 20 colleges (mapped as points) showing the percent share of engineering degrees earned by award level (i.e., assoc, ...
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1answer
379 views

Calculating shadow of trees with DEM in QGIS?

I have a DEM with a good precision (0,5 x 0,5 m/pix LiDAR) and I´m looking for the way to obtain a raster (or shapefile) with the shadow of the trees located in that place for a whole day (ideally ...
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0answers
95 views

Change detection using DEMs of difference and error quantification

Im currently working on a project in one of my seminars at university ("Advanced methods in natural hazard research"). We are modelling DEMs with Agisoft Photoscan using pictures from flume ...
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1answer
388 views

SAGA hydrology toolbox Error: select a library

I am having trouble getting the SAGA hydrology toolbox running. Here when I try to fill sinks in the DEM a series of errors are flagged in the log file. This includes for 'select a library', 'DEM' and ...
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17 views

DEM colour themes add-in for QGIS [duplicate]

Is there any plugins / add-ins for QGIS that give more of a variety than the default colour ramps?
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1answer
46 views

Viewshed Analysis for Custom DEM file [closed]

I am new to qgis and trying to do 2 things. My objective is to have an accurate viewshed analysis at the end. But my DEM file is of poor resolution. I do have a shapefile with building height ...
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0answers
16 views

Calculate average slope values for a point using 50ft vector perpendicular to contour

I am trying to calculate the average percent slope of a hillside on either site of a data point. I tried extracting info from a DEM using a radius around the point, but I believe a more accurate ...
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29 views

Creating DEM in GRASS?

I need to create DSM and DEM with resolution 0.4 m. I tried to create DSM with resolution of 1m, everything was ok, but when I set higher resolution, then raster have a stripes with No Data values. ...

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