Questions tagged [dem]
For questions about Digital Elevation Models (DEM), Digital Terrain Models (DTM) and Digital Surface Models (DSM)
2,059
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Hydrology Analysis using DEM [closed]
After clipping the DEM data of my desired area when I perform "fill" or "flow direction" of hydrology analysis tools, no data has been shown.
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Raster legend shows erroneous range, selecting Actual Min/Max Value Settings doesn't fix it
I ran Fill Sinks (Wang & Liu) on a small DEM. The elevation range on the input was about 39 to 235. The range for the output was about 128 to 771.
My understanding of this tool is that it should ...
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Find lowest value of nearby points [closed]
Essentially I need to create a point one foot away from multiple parcel boundaries where the adjacent sewer line has the lowest elevation. These parcels do not intersect with these sewer lines (sewer ...
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47
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My DTM File is somewhat altered or missing when I import it into QGIS [closed]
What is happening to this DTM? I'm trying to delineate using this DTM but this is what I get when I import it unto QGIS. This is a 1 m x 1 m DTM of the Cebu province in the Philippines.
The first ...
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31
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How to create image(DEM) with countour and buildings shapes
I'm GIS beginner and I'm trying to make a DEM with building's height.
Step 1 > I get a countor shape file.
Step 2 > Generate a DEM.
Step 3 > I get a Buildings shape file.
And then, how can ...
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27
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lidR: Creating tiles from a big .laz file
My problem:
I have big ALS .laz files and I want to calculate DSMs out of them.
For now, all my work starts with retiling the original .laz files into smaller ones. I began to hesitate when I read the ...
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25
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Slope and Aspect layers masked when using ee.Terrain
I am trying to create a slope and aspect layer using mosaicked 1m and 2m LiDAR scans. The DEM appears fine but the slope and aspect layer are masked. I've put my code below.
I'm quite new to GEE. The ...
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28
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Alternatives for creating DTMs with LM-Editor from VertiGIS
I currently only know the option of creating official digital terrain maps with the VertiGIS LM editor. (=digital representations of geographical features with detailed information about terrain, ...
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ArcGIS Online; Calculation using raster DEM value
I am pretty new to ArcGIS online and am trying to figure something out.
I have a map I am creating with the only layer being a raster DEM. When a user selects the location it reports the DEM value. ...
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Standardizing LiDAR processing for meter and feet projections: lidR package
I am creating an R script with multiple different types of LiDAR data, some in a meters projection and some in feet. I therefore need to convert some of the units in my script from meters to feet in ...
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Subtracting a glacier thickness raster layer from a DEM layer
I have two raster layers:
One contains multiple polygons showing the thickness of glaciers, and the
Second one being a DEM layer of the area (including the glaciers).
I am trying to subtract the ...
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Auto generating polygons similar to initial study area in QGIS
In QGIS, I have a DEM and a polygon of my study area. My goal is to generate other polygons that have similar features as my study area (i.e. elevation range, slope, aspect, surface area).
I managed ...
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Why is there a difference between Raw and Rendered results?
I saved two images from a Dem Tiff file in two different formats. There is no problem when saved as raw format. However, when you save it in rendered format, something like the second picture appears. ...
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QGIS point sampling misses data on edge of raster (possible bug?)
It seems I may have discovered a shortcoming in the way QGIS handles raster sampling in points. Since yesterday evening (18/7), one small issue has begun to elude me (during my comeback geofictional ...
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Reprojecting to rotated orthographic projection in rasterio
I have some DEMs in a lunar polar stereographic projection (from LOLA). I would like to reproject them to a orthographic projection with a custom azimuth rotation using rasterio. I can pretty easily ...
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QGIS fill individual sink
I’m trying to determine the maximum extent of a pond when it is filled to its maximum capacity.
I think this is the same logic as the sink filling algorithms used for hydraulically correct dem’s - but ...
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Brightness Differences in DEM TIFF File
I created a DEM file with QGIS. File type TIFF. The files I use as sources are also TIFF. The file, which looks normal in QGIS, looks different when I look at it in other programs. When I open the DEM ...
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Why does my raster look different after clipping it by a mask layer using QGIS?
I have a Digital Elevation Model of Europe and I want to clip it to the extent of Germany. To do so, I am using Clip Raster by Mask Layer with the external frontier of Germany as the mask layer. ...
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WGS84 elevation from ALOS 30m DSM tif's using rasterio
I am new to GIS processing.
I am trying to compute WGS84 elevation for given latitude and longitude using the JAXA ALOS 30m DSM. I use rasterio and code from a minimal example I found that looks like ...
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447
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130 TIF DEM file (total size 3 GB) become 7.4 GB TIF file after merging. Why?
I combined (Merge) 130 DEM maps via QGIS, taking up 3 GB in total. However, the total size of the combined file was 7.4 GB. I'm new to QGIS. It's only been a few weeks. I don't understand why the file ...
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Merging DEM with different resolutions
I am going to merge two DEM raster files with different resolutions (5m and 12.5m). I would like to merge them in a way that they should keep their own resolution.
How can I do this in ArcGIS Pro?
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DEM < 10 Meters - Greece
I would like to know if there is any free or to buy option (site) from which I can buy/download a high resolution DEM for a small region in Greece. Except from USGS and OpenToography where the ...
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Combine DTM with hillshade in QGIS
I'm wondering if it is possible to combine a LiDAR generated DTM on a 1m Scale with a Hillshade DTM on a 0,25m Scale to improve the level of detail of the LiDAR DTM.
If possible how can this be done ...
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GSD or pixel size for volume
When I want to calculate the volume of a building polygon (in my case), do I use the GSD that I received in a WebODM report or the pixel size of the elevation raster? What is the difference between ...
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Issue generating DEM with Natural Neighbour in QGIS 3.6 on different computers
I am trying to create a DEM using the Natural Neighbour algorithm in QGIS 3.6 Noosa. On my personal computer, I can successfully generate the DEM despite encountering a warning (shown in the attached ...
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QGIS DEM to elevation Points, pixels not centred
I have a DEM which I'm trying to convert into a point layer in QGIS. I used the raster pixels to points tool, which seemed to work, except that the points are not in the centre of the DEM pixels. They ...
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QGIS: Set two raster to the same height
I have 2 DEM raster in QGIS. I want to merge them, but they have a difference in height of approx. 9m. This means that when I merge them, there is a kind of break-off edge at the transition. Can I ...
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494
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What does "post to post" mean?
For example, when someone talks about the "post to post" elevation error of a DTM, what exactly are they referring to?
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What type of web service do GMRT and OpenTopography offer?
From what I understand, GMRT and OpenTopography offer web services for DEMs in geotiff format (raster with unique band of 16 or 32bits) whereas OGC web services serve 3 band rasters.
What's the name ...
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Find Python library to work with DEM in GeoTIFF format [duplicate]
I'm looking for a library for Python that will allow me to do the following thing:
I have a DEM in GeoTIFF format, and I have a list of points with coordinates in Lat/Lon format. I need these points ...
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Calculating accurate viewsheds using DSM and DTM lidar data QGIS
I have a question regarding using DSM (Digital Surface Model) and DTM (Digital Terrain Model) data sets to create Zones of Theoretical Visibility.
I used the QGIS Visibility Analysis plugin to create ...
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Choose DEM layer as terrain in 3D view using PyQGIS
I saw that many 3D classes and methods have been exposed to PyQGIS so I was wondering if choosing a raster layer as a terrain was now possible. I'm working on QGIS version 3.36.1.
This is the GUI ...
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QGIS: Further subdivide sub-catchments based on DEM
I have a DEM and a vector layer with existing hydrological sub-catchments. Is there a way in QGIS to further subdivide the sub-catchments based on the DEM?
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How to augment LiDAR/DSM data from 3d models
For a viewshed analysis in QGIS 3.34, the I have LiDAR/DSM geotif files available. I want to modify/augment the DMS layer by adding the height information from 3d models of specific buildings. This ...
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Importing DTM from WMS
I used a GetMap request to query a DTM layer (French national DTM coverage called RGE ALTI) in GeoTIFF format. However the resulting layer has 3 bands instead of one. My end goal is to visualize it in ...
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Information in addition to Raster zonal statistics
I have a layer of polygons and a DSM. I want to know if I can extract average aspect, slope, and elevation statistics all at once in QGIS. I know another software does this but I forgot the name.
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QGIS - transfer outcrop pixels from a DEM raster onto another raster surface at a lower level
In QGIS I would like a solution that will transfer pixels from a DEM raster onto another raster surface at a lower level. I am trying to create 2 geological surfaces, one being ground level (GL) and ...
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Starting from a DEM raster, is it possible to arrive at a polygonal layer with a slope greater than 30% not in squares?
On this site it is possible to download DEM maps of Italy with an accuracy of 10 meters: https://tinitaly.pi.ingv.it/Download_Area1_1.html
Bringing this raster into QGIS and running the Slope command ...
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Raising/lowering extracted contour layer using QGIS
Is there a way to raise/lower an extracted contour layer?
I've scoured the properties panel and have tried to raise/lower "elevation" menu, but when I make changes there nothing happens to ...
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DEM update/interpolation algorithm from control points
Context: I have a reference DEM, and Icesat-2 points covering some parts of it. The DEM is from 2012 and the Icesat-2 points range from 2018 to 2023.
Goal: I am looking for a way to 'update' the ...
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Using CreateMosaicDataset_management and AddRastersToMosaicDataset_management in ArcPy
I have a standalone ArcGIS Enterprise Server 10.8.1. I am also using ArcPy with Python 2.7.18. I want to publish an Image Service to my server by creating a SD file, given a folder of DEM .tif files. ...
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Make a slope-aspect map and create a circular legend for it in QGIS
I'm working on Terrain analysis of my ROI and could compute aspect and slope separately. Although I found a fairly easy tutorial on how to make a slope-aspect raster, I want to know if it's possible ...
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Combine Slope and Aspect of a DEM for suitiable PV-Powerplants
I want to get areas for PV-Powerplants via QGIS.
I used the solution under Filter for south pointing areas from a DEM for extraction of the areas which are not facing north (60-300°).
But I need ...
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Python CLI/Package to handle DTM conversion from raster to mesh (obj or ply) [closed]
I was wondering if there is a Python CLI, package or even a QGIS tool that makes it possible to convert a DEM from raster to mesh. The only way I found at the moment is sampling points from the raster,...
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Wrong elevation of DEM
I received a DEM made without calibrate the elevation with ground control points, the result is a DEM with 5 m below the real surface. How can I fix this issue if the plane coordinate are perfect, the ...
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Load granule subset (tiles) from mosaic based on shapefile footprint (grid) with QGIS
I downloaded DTM RGE ALTI® from french IGN here
The directory contains a mosaic of granules :
I would like to load only a subset of the mosaic.
The dowloaded product contains a shapefile named ...
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206
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QGIS Drape (set Z value from raster) to set Z-value along all pixels under a geometry (not only vertices)
In QGIS (3.34 at the time of writing), the "Drape (set Z value from raster)" algorithm (native:setzfromraster) allows the user to assign a Z value to a given vector geometry using a raster ...
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Conversion of a DEM model from Baltic Height system 1977 to EGM96
I have a raster DEM model (geotiff) with horizontal coordinate system EPSG:4326 and vertical heights regarding the Baltic Heigts system 1977 https://epsg.io/5705
I'm trying to convert it into EGM96 ...
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Elevation discrepancy while clipping a DEM in QGIS 3.28.9
I clipped a DEM (Clipped mask) using the GDAL Processing Tool - clip raster by mask layer from a DEM (clipped).
The maximum elevation value of the Clipped mask is 7286m, while the same in the clipped ...
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Points-Elevation from DEM via WMS
I am trying calculate elevations of points (which I collected via GPS on phone) to save as a base line of study area. Here is what I did: First, input the points as geotagged images to QGIS. Second, ...
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