Questions tagged [dem]

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

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19 views

General slope inclination in ArcGIS Pro [closed]

In my master's degree I am writing about postglacial seismicity. I am doing a spatial analysis of the area I am analysing. The analysis is based on a DEM dataset that I have run through the hillshade ...
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1answer
22 views

Querying (DEFRA) height data from WSM, what's wrong with my GetFeatureInfo parameters?

I'm trying to retrieve DSM/DTM data from UK DEFRA WMS services in order to render in 3D. My background is in programming rather than GIS, although I've been dabbling a bit for a little while. I have ...
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27 views

Contour polygon created at different intervals than the desired interval

I have a DEM in WGS84 coordinates with a minimum elevation of 2083 meters and a maximum elevation of 3000 meters. I then used the Contour tool in ArcGIS 10.7 to create contour polygons at an interval ...
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24 views

Reclassified raster to separate polygons

I have a DEM reclassified into 5 bands and I want to convert each classification into a separate polygon. Since, I have 5 classifications, hence 5 polygons will produced. Can I do this in ArcGIS?
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15 views

Identify Number of Ground Control Points in DSM Using GDAL

I am trying to use GDAL (in Python) to extract metadata from a digital surface model (.tif). I am using the "gdalinfo" command and applying different flags (e.g. -stats, -mm) to get ...
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9 views

Followed “InSAR TanDEM-X Bistatic DEM workflow” in ENVI but the results seems not good

I been processing the TanDEM-X for producing DEM using "InSAR TanDEM-X Bistatic DEM workflow" using ENVI scarscape but some of the results turned out to be wrong somehow meanwhile some are ...
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0answers
32 views

Getting characteristic high points from DEM

I use QGIS 3.14 and I have a DEM file which I'd like to use to get a point layer with most characteristic high points from that DEM. So every top of the mountain, hill, hillock, low etc should be ...
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1answer
47 views

Seeking open source alternative to Spatial Analyst / 3D Analyst toolbox of ArcGIS Desktop

Is there a decent open source software alternative for the Spatial Analyst / 3D Analyst toolboxes of the ArcGIS environment? The main goal would be to demonstrate DEM interpolation and/or ...
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1answer
44 views

Calculating Slope from DEM in QGIS

I have a world DEM raster in QGIS in EPSG:4326 with elevation units in meters. I'm trying to get a raster of the slope of the terrain, and I'm doing so using the "Slope" tool under "...
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1answer
37 views

DEM for Russia in WGS84 [closed]

I'm looking for a DEM of Russia projected in WGS84. Anyone have any ideas on where to look?
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44 views

Using Aspect tool in QGIS

For my bachelor thesis in biology I´m working with QGIS 3.14 (Pi) and tried to create a layer where the slope aspect/expositon/exposure is presented. I´ve got a DTM1 on hands. There is this function ...
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2answers
37 views

Identify the coordinates of the max values resulting from using the Zonal Statistics tool

I used the Zonal Statistics tool to extract the max values of a raster/DEM layer. The attribute table shows the result, but the problem now is to identify the coordinates of the said maximum elevation....
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30 views

Meaning of statement in GRASS r.horizon manual

I have a question about this statement in the r.horizon manual: "If your projection is based on distance (easting and northing), these too must be in meters. The buffer parameters must be in the ...
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1answer
24 views

Modelbuilder Rastercalculator ERROR 000539

As part of a larger model for iterating lake bathymetry interpolations, I'm essentially trying to establish the lake altitude as a new base level (Z=0) for the DEM surrounding the lake. (picture below ...
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1answer
39 views

Get altitude value from WMS

If I load a WMS service into QGIS I could query with the selection tool for every pixel the altitude value. Where does QGIS get this altitude value from? A WMS does not normally have any altitude ...
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1answer
43 views
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77 views

Merging DEM and DSM into single raster

First things first, I am completely new to this so please bare with me if this is a bit unclear as I lack the vocabulary. I have two raster layers (a DEM and a DSM). The DEM layer covers a large ...
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10 views

How to sum pixels of two overlapping rasters with different extents

I have two DEM rasters which overlap and have different extents. I would like to create a new raster which sums the pixels where there is an overlap. I tried using gdal_calc first by doing A+B but ...
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14 views

Order of reading in Row Ordered USGS DEM (.dem) file

I am making a .dem file parser and so far https://web.archive.org/web/20180612184054/https://nationalmap.gov/standards/pdf/2DEM0198.PDF has proven very useful in providing the information needed. ...
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48 views

Optimizing identification of tree stand boundaries

I am working on a workflow to identify tree stand boundaries. My desired result is the blue lines - I know it will never be like that, but I need it to be as good as possible. My best result is the ...
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41 views

Generating DSM and DEM from processed LiDAR (TIFF) on ArcGIS Pro

I have a "processed" LiDAR that is available as TIFF, I do not know how it was processed although I've read about the method of converting a LAS dataset to Mosaic, terrain, etc. I was ...
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1answer
27 views

Change rasters' z value to minus (Below sealeave)

My current raster has positive values for all features but I need them all to be negative as it is for a seafloor basin. A handful of values are negative but most are positive. I have access to ArcGIS ...
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21 views

Blending two overlapping DEMs using ArcMap [duplicate]

I have two point clouds with X,Y,Z which have been converted to DEM's. One is more accurate than the other. The point at which they overlap (just a 100m strip) however is very uneven. Is there a way I ...
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1answer
81 views

Making a heightmap DEM for use in putting together a relief

I'm new to GIS, and I'm just doing this as a hobby. I've seen 3d relief maps like this one: https://i.redd.it/peq57uoa28c51.jpg and I wanted to try my hand at making my own. I used the topoView ...
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44 views

QGIS Slope not working properly

I'm new in QGIS and I have been having an issue with it. The thing is that I'm trying to get the slope and relief of a zone. I have the contour lines, from that I created the DEM with 'Rasterize' > ...
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24 views

How do I stop QGIS from crashing when trying to create a DEM from a contour line file?

I am trying to use the same methodology I have used in the past to create a DEM from a line shapefile containing contours. However, it keeps crashing when I follow this methodology. (Using QGIS 3.10.9 ...
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22 views

LAS to Old Format USGS 7.5 DEM

I'm trying to use an old software that only imports the old style USGS DEM info. I've found somewhere to download an entire quadrant of which I need about 1 percent. I have a current LAS file of the ...
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45 views

160180: The junction has invalid geometry (i.e., non-point or invalid location)

I made the following In ArcGIS Pro: I created a point layer from elevation lines (every 10 meter, in total there is 5.5 million points). TOPO TO RASTER- When I run this tool with the point layer from ...
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23 views

Problem with overlaying polygons onto DEM with qgis2threejs plugin

I am trying to export a scene using qgis2threejs, adding a polygon layer overlay on top of a DEM and a satellite image. After exporting, it looks like the polygons don't overlay onto the DEM correctly....
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1answer
55 views

Managing large numbers of raster DEMs for QGIS

I have a large number of (say 9000) 2km x 2km raster DEMs in ASC file format that I am trying to manage, in order to use in QGIS. I've been looking for way of storing them, ideally on the filesystem, ...
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2answers
125 views

Prepare DEM in QGIS to open in Blender [closed]

I have been having trouble loading 30m SRTM files into blender. I download the SRTM (DEM) 30m files from the earthdata (NASA) website and I would like to prepare them in QGIS (making mosaic, clip, ...
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42 views

How to avoid error in “SAGA Strahler order”-process when running it on a merged terrain model file

I am trying to create a catchment in QGIS 3.8 following this tutorial: https://www.youtube.com/watch?v=2fvy9xtAHc4 However, my terrain model is originally divided into 4 overlapping tif-files. I can ...
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24 views

QGIS Slope Analysis produces strange values [duplicate]

I am performing a slope analysis (Raster>Analysis>Slope) of a US Geological Survey DEM. I am calculating the slope of a raster DEM saved as a TIF. I set up the slope analysis as per the picture ...
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1answer
56 views

How to find out which areas are affected by flooding due to heavy rain?

I'm working on a little project to visualize affected streets of flooding due to heavy rain. I already got a DEM for my study area and filled the depressions with r.fill.dir. Since I never worked on ...
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36 views

How to use French LiDAR CSV data in QGIS

Following on from this Assign elevation data to GPX from LIDAR data Please could you help with another problem. I'm trying to use the LiDAR data from France ( http://ids.equipex-geosud.fr/web/guest/...
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1answer
36 views

Splitting DEM based on elevation using ArcMap?

I am trying to split a DEM TIFF file into three separate shapefiles (upland, middle and lowland) on ArcMap 10.6. I have used natural breaks to classify the DEM into three elevation categories. How do ...
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1answer
37 views

“Optimized” TIFF file render slower than big original in GeoServer?

I struggle to "optimize" my rasters for publication on GeoServer. My original raw GeoTIFF raster render before my "optimized" and I don't understand why? The original file is at ...
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15 views

Using WCS DEM data for make slope and aspect maps in QGIS [duplicate]

I need to do several slope and aspect analyses (hundreds). Instead of downloading an ASCII for each location, I want to extract/clip the elevation data from wcs and do the analysis. This is the WCS ...
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0answers
35 views

How to get a more refined and smooth DEM?

I have Two DEMs (Digital Elevation models) DEM (Image 1) - received from my institute DEM (Image 2) - downloaded from srtm Both DEMs have been styled similarly. But DEM (Image 1) looks better than ...
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8 views

gdal_merge with python for PDS4 does not generate xml

When I use gdal_merge to merge two LOLA PDS3 DEMs* into a PDS4 DEM, I do not get a PDS4 xml file. It creates the img file just fine but it does not create the xml file. I am using Python 3.7.6 in ...
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29 views

functionality of Surface volume tool in ArcMap?

I'm using the surface volume tool to calculate multiple volume below a plane height. Starting from the lowest value of my DEM, I perform several calculations in 0.1m intervals. However I'm not ...
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1answer
32 views

Integrating RGB image and nDSM data [closed]

How can I integrate RGB image and nDSM data provided in the dataset (ISPRS Vaihingen) that I want to use in a multimodal deep learning based semantic segmentation method? Can anybody provide a Python ...
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0answers
7 views

ALOS nodata pixels

I suppose that I'm using the right ALSO PALSAR 12.5 m DEM archives (*.tif). I used raster calculator to remove negative value (-31 m) to positive ones. But how can I turn "nodata" (white ...
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1answer
15 views

Levelling an existing site in DSM for viewshed analysis in GrassGIS

I'm doing a multi-point viewshed analysis for an urban site in GrassGIS based on a LIDAR DSM raster maps, to test for a series of proposed buildings. The site has existing building on them. Is there ...
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39 views

QGIS 3.10 create DEM from height contours - the maximum height values of the grid to do not match the maximum height values of the contours

I have created a DEM using contours spaced 10 metres via QGIS grid ITN interpolation method based on height (metres) cell size 10 pixels/metres in QGIS, and another grid of 5 pixels cell size. When I ...
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0answers
18 views

Calculate angle of view from a point based on DEM using QGIS

I'm looking for a way to calculate the angle of view from a point on a DEM, in particular from the highest point of a terrain relief (corresponding to the red dot in this image below). To better ...
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0answers
19 views

ArcGIS Pro not accepting negative volume value for Cut Fill

I am using the Cut Fill tool of ArcGIS Pro to calcuate volume change in DTMs over time. I am hoping to visualise these on a map where Cut (volume removed) is blue and Fill (volume added) is red. I was ...
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1answer
17 views

Quickly digitising several polygons based on classified raster output using ArcGIS Spatial Analyst

I have a raster DTM of a river which I would like to split into 90 sections, each measuring 125m. I have used Euclidean Distance to outline each section by reclassifying the symbology to change colour ...
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2answers
51 views

Using ArcGIS to split a raster DTM of a river valley into equal parts/sections?

I would like to split a raster DTM of a river valley into several (maybe 30) equal sections. The raster currently follows the river channel and so is not a straight line but bends and moves like a ...
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0answers
14 views

How to respond to marginal height error when using LiDAR DTMs in ArcGIS

I am comparing DTMs of a river valley over time using LiDAR data from the DEFRA download website. The Environment Agency state that this data has a relative height error of +/- 5cm. The problem that I ...

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