Questions tagged [dem]

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

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How can I improve the accuracy of a DEM using surveyed points?

I have a DEM and many surveyed points in the area. The survey points have centimeter accuracy. The difference between the DEM to the actual height ranges from -20cm to +20cm. It is not a uniform ...
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Separate canopy from ground - based on DEM generated from thermal imaging

I've never worked with QGIS but I need to use it for a project. I have thermal images of a vineyard that were added together in Agisoft Metashape to form a DEM (tif-file). When I load this into QGIS I ...
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Merge a .gpx with a DEM

I have two files, a DEM and a .GPX. How can I mix the two files so that the .gpx is part of the DEM (in black and white), but rendering the color at an elevation 10m higher than the DEM? The color of ...
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Update DEM based on line feature in QGIS

I have a DEM which I like to update with a line feature to get some kind of line extrusion. Every cell of the dem overlapped by the line feature should have for example +10 added to it's raster value. ...
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QGIS Apply Correction to Elevation Datum

I am wanting to apply a blanket correction to a bathymetry layer i.e. add 2m to every DEM cell. I assume I do this in the Raster Calculator but I'm unsure of the command line to use.
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QGIS Merge two DEMs of different resolution

In QGIS I am trying to merge 2 DEMs of different resolutions where there is a slight overlap between the two i.e. merging a bathymetry DEM with a topo DEM across a shoreline. As it is of a higher ...
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Artificially extend a DEM to clip it

I have a DEM that is slightly too short for one of my shapefiles. I would like to extend the DEM to the North so it covers entirely the shapefile, and then clip the DEM to the extent of the shapefile. ...
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In QGIS change DEM elevations values from positive to negative

I have a DEM that currently has positive elevation values for bathymetry and negative values for those above sea level. How can I convert these cell values to negative for bathymetry and positive for ...
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Saving Mapzen Global Terrain in QGIS with extent layer (-90 to 90 Lat and -180 to 180 Lon)

I am working on the elevation data from Mapzen Global Terrain. When I save them into GeoTiff, there is a CRS option in which I use ProjectCRS: EPSG 4326 - WGS84. However, when looking into the Extent ...
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Cannot set my DEM in ArcScene to 3D

I read other responses saying that DEMs will automatically appear as 2D, but you need to drape your DEM over itself. Those instructions included opening the properties and clicking on the Base Heights ...
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Weird issue in orthophoto of canpy in rough terrain

After postprocessing drone imagery of a forest area in rough terrain, I had a weird issue such as in the images below. The effect is like the cropping of trees following the DSM. If you have ...
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Infer the topobathymetric surface of a reservoir

I have a DEM that just represents the water surface of a reservoir, and I would like to infer its depth geometrically, as shown below: ideally i would like to get a 3d line of this reservoir bottom, ...
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Vertical datum transformation in ArcGIS Pro

I'd like to compare USGS 3DEP DEM with SRTM DEM for western U.S.. I did some research here, and find out that I need to match their datum (from NAD83-NAVD 88 to WGS84-EGM 96) before comparing the ...
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Adding lines to polygons in QGIS

I'm mapping quick clay risk areas and have extracted areas which could trigger slides (slope > 1:2.5; height (min/max) > 5m). The areas are separated into zones of roughly equal aspect (30 deg), ...
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Create longitudinal profile of a stream out of a river system in QGIS

I have been using 'profile tool plug-in' in QGIS 3.20.1 to visualise longitudinal profile of the river in QGIS. Selection options, i.e. temporary polyline; and selected layer, are working well. ...
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Delineate valley floor and valley width in SAGA GIS [closed]

How can I delineate valley floor and compute valley width in SAGA GIS?
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6 votes
1 answer
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Merging drone/photogrammetry-derived DEM and satellite-derived DEM using ArcGIS Pro

I have a DEM that was produced from drone images at a site of interest, processed through Agisoft Metashape. Because I used a drone, the site-level DEM boundaries/edges are irregular rather than ...
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DEM loses data after clip raster

I'm working on a project in ArcGIS Pro in which I need to use DEMs and LiDAR data to estimate tree heights. Unfortunately, some of the DEMs I have to use are at 10-meter resolution, and they cover ...
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3 votes
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LiDAR derived streams - map scale

Historically, streams were defined by the map scale. For example, for a map with a scale of 1:24,000 would mean that the streams identified on that map would be 1:24,000 streams. With streams that are ...
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QGIS Contour Vectors to Raster

I'm wanting to create a DEM from vector contours but whatever tool I use, it fails to identify the sea level contour at elevation 0. I have tried via GRASS v.to.r, QGIS tool Vector to Raster and QGIS ...
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Skiable upslope area of specific point on DEM using QGIS

I am looking for a way to determine the area above a point that can be reached by only walking up or horizontally. Or in a bit more technical terms, I am looking for an algorithm that starts a ...
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Computing drone camera footprint over a DTM

I am developing a Python application to compute the footprint of aerial videos. I am able to compute the footprint when the sensor is parallel to the terrain and the terrain surface is plane. Now, I ...
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How do I calculate high water extents?

Could someone suggest the right path to follow if I were looking to calculate the high water extents or potential flooding that could occur on a tidal river. I am working in ArcGIS Pro and have ...
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Create raster of aspect relative to the nearest road

I know that slopes which are downhill from the nearest road are an important raster layer for my model (example application: cars carry seeds on their wheels. The seeds fall on the road and downhill ...
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Why is the ASTER GDEM called digital elevation "model"?

The ASTER GDEM provides the elevation data for a region on the earth surface. Why is it called digital elevation "model", but not "data" or "observation"?
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1 answer
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Cut out/burn in DEM along street polyline with different heigth, width and elevation of the cut

I have a task to do and can’t seem to find the right tools for the job. Below you can see two graphics to demonstrate my task. I need to cut off/out some parts of a DEM to unearth several street ...
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1 vote
1 answer
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How to combine a topographic DEM with an overlapping bathymetry

In QGIS, I had a larger DEM that captured the lake surface and a smaller DEM of the lake bathymetry. I spent a while trying to figure out smart ways to combine the two so as to replace the DEM lake ...
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1 answer
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Flipped Contour Polygons from GDAL

UPDATE # 01 : Links to related past questions: Mirrored Contours from DEM in QGIS gdal_translate creates images that are mirrored This question has been asked before, but I can't fix my personal ...
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3 votes
1 answer
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QGIS Raster Hillshade Classic Drawing Texture

I found this drawing of a valley and really like the texture of it. I suppose this is a sort of hachure map drawn with dots. I was wondering if it was possible to recreate something similiar in QGIS (...
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1 answer
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Locating / identifying depressions on a DEM (QGIS)

I have a 1m DEM and on this DEM I want to locate the surface depressions. For a reforestation project I would like to know the surface depressions because of the effect they can have on soil moisture ...
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QGIS - calculate volume from DSM

I've been following a tutorial (https://www.pointsnorthgis.ca/blog/how-to-calculate-surfacecut-volume-qgis-advanced/) in order to try to find volumes for various stockpiles that I took imagery of with ...
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ZVI Analysis Tool - unexpected results

I have run the ZVI analysis tool from the perspective of an observer standing on a hill looking out to a defined altitude. However, the results do not correspond to my expectation from the ...
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Interpolated DEM RMSE

I'm trying to figure out the 'true' error associated with interpolated cells in a DEM, which itself is known to have a RMSE of 0.15m. DEM has RMSE of 0.15 Interpolation model shown by cross-...
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High-resolution Lunar Topography import into QGIS. Float img format?

I don't know how to import these float img files into QGIS https://pgda.gsfc.nasa.gov/products/54 Ultimately I want to be able to export them as 16bit PNG's but I'm stuck now knowing how to import ...
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Terrain correction in SAR image

I am new to the gdal utility. Using DEM data of the Moon, I am trying to perform terrain correction on SAR images. I have a DEM file and SAR data into tif file format. Both DEM and tif file are in ...
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Seeking ways to improve rendering of surface water in shaded-relief images

I have a question about techniques for depicting surface water features in shaded-relief (hillshade) rendering. I’ve written some Java code for rendering elevation data from the USGS Cloud Optimized ...
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1 answer
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How do you calculate area within separate 100m elevational bands from a DEM in R? [closed]

I am trying to calculate the area within each 100m band of a digital elevation model (DEM) raster in R. Does anyone have suggestions on how to do this?
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Importing Survey Triangles in DWG format to QGIS

I have a DWG with survey triangles of a site. I want to import this into QGIS so I can convert these triangles as a DEM in QGIS. When I use import function it just adds all the layers into QGIS. How ...
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Add legend, north arrow, and scale bars

I have three DEM layers on QGIS. They show slope, aspect and coloured DEM. I need to add a legend, north arrow, and scale bars to them but I'm completely confused at how to do this. The data I am ...
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0 votes
1 answer
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Finding elevation of polygon [closed]

I am trying to find the elevation of a flood polygon. Is it possible to do either using ArcGIS or QGIS or in Python? I understand that for the point feature, we can find it but what about multiple ...
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Incorporating bridges into DEM for route profiles

I'm using ArcGIS Pro. I'm making transit route elevation profiles to see how the topography changes over the course of certain bus routes. The data I'm working with: DEM of the study area GTFS tables ...
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3 votes
3 answers
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Extract hills from DTM in QGIS

I am struggling with a problem that I cannot solve. I state that I use QGIS 3.16. I have the dtm of a hilly area with 5m x 5m cells. I would like to select all the cells above a height so as to have ...
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1 vote
1 answer
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Options for making a DEM of single-return point cloud?

I have a project site surveyed with single return photogrammetry so, all points are unclassified. It was not a problem to create a DSM of this data, but I also need a DTM. What are my options? Will I ...
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2 votes
1 answer
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Join islands in raster object

I have a raster with elevation information from the SRTM data. I want to use topoDistance to calculate topographic distances between points in this raster. However, there are islands which are not ...
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Converting raster to DEM using QGIS

I have a .jpeg file with three channels, and would like to convert this to a DEM to generate contours lines to export as a vector. I've added a screenshot below of the image in qgis, and a profile ...
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''pixelatted'' ''griddy'' result from slope function (QGIS) [duplicate]

I use the SRTM downloader to download my DEM's, then it happens very often that when I create a slopemap there are weird artefacts in the slope map. Something I do before making the slopemap is ...
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QGIS: Exporting breaklines/linear structures from DEM

I would like to export the breaklines, such as road contours or river banks from a DEM. Is there any extension, which would make it possible? I already checked all the solutions, which I found in ...
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Open ALOS PALSAR DEM in QGIS

Does anybody know how to open an ALOS PALSAR DEM in QGIS? There are two TIFF files included, but, their volume is very low and also the quality. I think there is another way of opening it. Since ALOS ...
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Clean DEM in QGIS

I'm attempting to create a DEM in QGIS from contours using the "Rasterize (vector to raster)" function. How do I create a DEM that is clean and does not have blank spots?
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35 views

DEM coordinates do not align other data layers

I recently downloaded Original Product Resolution (OPR) Digital Elevation Model (DEM) data for some analysis. The DEM does not align with any of the other data sets I have for the area. I have ...
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