Questions tagged [dem]
For questions about Digital Elevation Models (DEM), Digital Terrain Models (DTM) and Digital Surface Models (DSM)
1,982
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DEM file contain some square grids after doing extracted by mask [closed]
I have a DEM file from SRTM portal. My study area is very small. After projecting my rater I did extract by mask. For extracting my study area DEM, output is not coming exact shape of my study area, ...
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18
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Generate and populate a grid from points in a geopandas dataframe [duplicate]
Context:
I have a geopandas dataframe, with two columns
'geometry': full of shapely.geometry.point.Point.
'h_mean': gathering the height of a surface at those points
I want to create a 2D spatial ...
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13
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What does the Fetch Analysis variable in Whitebox Tools represent?
I have a DEM of Scotland. I used BreachDepressionsLeastCost to process it. I then derived the Fetch Analysis raster. The problem is that the values, both positive and negative, are very high. The ...
3
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36
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Reading GeoTIFF from path and converting it into PostGIS raster data type
I need to read the raster file (DEM) from path directory and turn it into PostGIS raster data type. I formed this SQL query:
SELECT ST_FromGDALRaster(pg_read_binary_file('D:\dems\img.tif'))
FROM ...
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33
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How to derive first return points from a raw LAS data file
I have a raw (never classified) las dataset derived from UAV that I am attempting to obtain a DEM, DSM, and eventually CHM from. I have successfully been able to classify ground points and vegetation ...
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2
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1
answer
212
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Blurry resolution when uploading DEM 5ft data onto QGIS
I am creating a map for the nature preserve I work at. I have been downloading Kentucky elevation data from THIS website. You can see that there is a really high resolution, and I am able to see the ...
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2
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3
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112
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Creating topographic "layer cake" map a.k.a. Tanaka contour in QGIS
I'm wondering if there is any way to create a map similar to the image below. Basically, it would be the contours extruded, add a singleband pseudocolor ramp as the color on top, and be able to ...
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17
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How to have a good rendering with mdenoise - DTM LiDAR denoising
I'm trying to generate a clean slope map from a LiDAR DTM. Due to LiDAR high resolution, the slope map is full of noise.
So to do this, I use mdenoise library.
It works quite well but it generates ...
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1
answer
49
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Check if Layer is a DEM programatically
I loaded several layers, some of them are DEMs of different data type: ASCII and TIFF. I want to check every layer if it is a DEM or not. I found the function hasElevation, which should return true if ...
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54
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Reprojecting raster in QGIS moves all values to completely different range
This question has been asked here multiple times. And every time, it seems that the people offering answers don't understand the magnitude of what's happening. When I reproject a DEM raster with this ...
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30
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How to calculate watershed associated with a polygon using a DEM
I have found instructions that outline how to determine the watershed uphill of a selected point using a DEM in QGIS (https://youtu.be/CE7zZCkFbg4).
I am starting with a polygon representing property ...
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14
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Applying D8 ( or other watershed algorithm) on urban areas with some artificial constraints
Referring to the post here on the limitation of D8 algorithm, or watershed algorithm in general.
From the post I have the impression that even though the urban areas have a lot of flat surfaces ( ...
- 928
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43
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Import/export of 22.900 Granuels (500GB) Aster Global DEM in ArcGIS
I have a concern. I have 22900 tiles of a global DEM. When I try to insert these via Mosaic to Raster, the program hangs. I would like to avoid the option of splitting these into 1000 packages and ...
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29
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Colour interpretation on ASTER GDEM files
I'm trying to understand the data in both the grayscale and colorized versions of the GDEM samples provided here: https://asterweb.jpl.nasa.gov/gdem.asp
I haven't found (looked hard enough) a ...
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47
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What is the hatch marking of my produced terrain slope raster?
I’ve been piecing together DEM raster data from different sources, in an attempt to create a terrain slope raster. I’m using ArcGIS Pro to merge the DEM’s together and then using the split raster tool ...
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64
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Extracting features from DEM using ArcGIS Pro deep learning
I was wondering if it's possible to use ArcGIS Pro Deep learning to extract features from elevation data?
I have a DEM with multiple levees that are used for flood defence.
Is there a way to train ...
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81
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Estimate solar potential in Python with DEM
I am trying to calculate the solar potential/solar exposure of the littoral zones for a few lakes in Python. I already got the bathymetry/topographic data but I am still searching for ways to ...
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2
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94
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Trying to get topography via elevation package Python
So I'm trying to get some topography. In Detail some parts of the panama canal. I tried using the elevation python package. Here is my code so far:
import elevation
min_lat, max_lat = 8.0, 9.5
...
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1
answer
154
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Using Google maps Elevation API to download Google elevation data directly to QGIS
I could use some help using the google maps Elevation API directly in QGIS for downloading elevation data in order to create a high resolution DEM for various terrains ranging from 10 to 100 ha.
I ...
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53
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Generate a very accurate mask showing where rivers and streams are using a DEM in QGIS
I would like to create a mask layer to show what the specific widths of a river or stream would be with certain variables. I'm using a high quality 1mx1m resolution DEM. I am able to do some things ...
2
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75
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Removing black background from the raster which has actual data pixels with value 0 in QGIS
I have a raster with the area of interest and a black background around it. The problem is I can't remove that area by putting 0 as additional nodata, since it's a DEM layer which has 0m elevations as ...
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36
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Calculating volumes
I am using QGIS 3.22.1 for this task.
I have points with X, Y, Z of river bed. I have two sets, first is top of the mud and second is bottom of the mud-gravel layer. My goal is to calculate difference ...
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63
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Reducing DEM raster file sizes in QGIS
How do I reduce the size (or clip to a smaller area) a DEM raster in QGIS using existing tools?
I need smaller files for QGIS project transfer into QField.
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160
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Create vector out of a DEM in QGIS
I would like to create a vector from my DEM raster so that it looks like the example I attached as an image. I want the altitude levels of the Alps in Austria to be represented in 5 different color ...
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3
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212
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Converting 5m DTM Raster to 0.5 m resolution in QGIS
I have 2 rasters (0.5m and 5m resolution respectively). There are some areas which the 0.5m raster doesn't cover. For these areas, I want to use the 5m raster. How do I merge these rasters into one ...
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34
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Line of Sight tool output does not match elevation of Sight Lines that are input
I'm trying to use the Line of Sight (3d Analyst) tool to determine new building obstructions. I have a DEM assigned to my scene and I have target and observation point feature classes with elevation ...
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27
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Unexpected artifacts when creating a digital terrain model (DTM) using lidR and gstat libraries in R
I'm using the lidR, raster, sp, and gstat libraries in R to create a Digital Terrain Model (DTM) from LiDAR data. I'm encountering unexpected artifacts in my DTM and I'm unsure why.
Here is my code:
...
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248
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Make the pixel values of the DEM correspond to the actual heights
I have a grayscale DEM. From the screenshots it can be seen that the min max value of the pixels range from 267 to 270. However from the generation report (using Metashape) it is known that the actual ...
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113
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How to make use of a 3 band DEM for analysis?
I have a 3-band RGB DEM raster. However, the pixel values are not very useful for any actual depth computations. How can I extract the depth values from the DEM?
I understand that it is not easy to ...
- 139
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45
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Vertical transformation of DEM from NAVD88 to CGVD2013 datums
I am attempting to recalculate a DEM raster from the vertical datum of NAVD88 to the 'new' Canadian vertical datum, which is CGVD2013. I've looked at a few similar questions but they only are geoidal ...
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112
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LiDAR LAS to DEM in QGIS 3.22 without LAStools
I'm using Ubuntu Linux and have installed QGIS 3.22 which has native support for LAS files. I think that LAStools is for MS Windows only?
I can load the LAS data and see a pretty image.
Next, I want ...
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42
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Clip a DSM by raster extent in QGIS
I am trying to clip a DSM by raster extent in QGIS. Both rasters have the same PCS (EPSG: 26911). My results appear a bit off axis from raster extent. Attached a picture; clipped DSM underneath ...
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48
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QGIS how to export slope data with x, y
I have a shapefile with contour line data, that looks like the following:
Columns 1, 2, 4, and 5 are geometric data and column 3 is contour data. (MultiLineString type)
First, I tried 'TNI ...
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42
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Contours of a DSM render slowly
I am comparing two digital surface maps (dsms generated from drone photogrammetry) taken at two times. The contour lines render quite quickly for one (in seconds) and quite slowly for the other (1–2 ...
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Google Earth Engine - slope
I am trying to use the pre-built function of GEE for calculating the slope of the terrain, but I cannot really understand how the function works, since the documentation is also not really helpful.
...
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1
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43
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Using Esri ASCII Grid as DEM + Reprojecting
I've downloaded *.txt files from this site: https://ide.cat/geonetwork/srv/eng/catalog.search#/metadata/model-digital-terreny-5x5-v1r0
I used Copy Raster tool to import one of the files with Esri Grid ...
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23
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How to do a location wise pixel correspondence between two different layers?
I have two separate rasters, an RGB orthophoto and a grayscale DEM of the same location. I need to run an object detection algorithm on the RGB orthophoto and then make the bounding box I receive ...
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42
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Dealing with million of points in QGIS
I have the survey data of millions of points (x,y and z) as .txt data (13 files). The distance of each point from one another is 0.15 m. I need to use points at a distance of every 0.9 m in order to ...
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26
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qgis2threejs and large area
In my project I am trying to create a model of a large territory (10 kilometres square area) through the use of Threejs plugin to be able to export it in glTF.
By opening the DTM and the ortho on ...
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Error QGIS 2threejs subdivided DTM
I am trying to figure out how to work with qgis2threejs plugin. Since I would like to be able to export as glTF file a an area with DTM and Orto as overlay (texture), I decided to begin by working on ...
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1
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264
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R: Extracting data from SpatRaster using points in sf class
I have several SpatRasters including: dem, dem_slope, dem_ascpect, dem_TPI, dem_TRI, dem_TRIriley, dem_TRIrmsd, dem_roughness, dem_flowdir. I also have sf class with x and y coordinates and one ...
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56
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QGIS equivalent to ArcGIS "corridor" tool for Least Cost Path analysis [duplicate]
I am working on solving a task in QGIS that is supposed to be solved in ArcGIS Pro (the examples given here are modified to not show the actual solution of the official task). Cost surfaces given as a ...
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57
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How do I create a polygon layer of high slope (>58%) area from a DEM in ArcGIS Pro
I am hoping to get from a slope raster (calculated from a 10m resolution DEM) to a polygon of areas above a certain grade (58%). I am using ArcGIS Pro 3.1. I have used the Raster Calculator tool to ...
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1
answer
44
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Problem with `terra::shade`: Neighborhood size parameter for hill shade algorithm?
The terra::shade hill shade algorithm only uses immediate neighbors to compute hill shading. In contrast, Google Earth Engine's ee.Algorithms.HillShadow has a neighborhood size argument, which can ...
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17
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Volume calculations using raster surface volume are too high
I am looking to calculate the amount of water stored on a wetland behind a sluice. I have used clipped 1m DEM data to calculate the volumes using the raster surface volume tool (calculating volume ...
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1
answer
108
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Way of creating "fake" DEM data in QGIS
I want to create a hypsometric map of a fictional island chain and I would like to know if there is a way of generation of a "fake" DEM data in order to have a basis for the map. I am not a ...
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165
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Which online APIs return elevation data without the height of trees and buildings?
I work on applications that generate topographic maps and analyze GPS tracks. My main concern is the presence of "bumps" due to the height of trees and buildings returned by the elevation ...
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22
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Creating time series flood inundation map using NetCDF future sea level and DEM
I want to design a GIS tool that visualizes flood inundation maps for future sea level rise. the data that I need to use are NetCDF of projected Sea level rise for 10-year slices and DEM. The idea is ...
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30
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Calculate volume of pit with geotools
I have DEM data in .geotif file. I want to calculate volume of pits. In geotools library implemented geotiffreader on 28 version. Can I calculate?
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27
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QGIS2threejs' display hugely miscalculated
In QGIS, when I display a digital elevation model (DEM) using the add-on QGIS2threejs, I get this:
I discovered, though, I get THIS when I change the Scene Settings > Z Exaggeration from 1.0 to 0....
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