Questions tagged [dem]

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

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6
votes
2answers
8k views

Exporting DEM-derived rasters to CSV from QGIS?

I have been able to import into QGIS a set of raster topographic maps and the associated DEM raster maps. It registered the two for me. From there I have calculated the associated slope raster map. ...
3
votes
2answers
17k views

Producing CSV file from .tif file with elevation data [duplicate]

I have a .tif file that contains all the elevation of a country. How can I convert that to a CSV file that contains x,y,z values where x and y are the latitude longitude respectively and the z ...
4
votes
4answers
3k views

Calculating peaks in DEM using GRASS

How could I extract all peaks from a DEM (large mountainous area) using GRASS? Peak means something like: a pixel which is sourrounded by other pixels with smaller elevation numbers in a area ...
1
vote
2answers
2k views

DEM/Raster Peak and Valley identification and/or elimination (non-generalization)

Is there is a tool or process that can identify and/or eliminate obvious peaks and valleys in a DEM? I have looked into smoothing at What raster smoothing/generalization tools are available? but I ...
2
votes
1answer
5k views

Spatially joining large raster to polygon shapefile

I have a large raster file with elevation data. From this raster, I would like to infer the average ruggedness for different geographic zones (like countries). I have the "countries shapefile" as a ...
2
votes
1answer
91 views

Orthorectifying or Georeferencing aerial photographs

I got 3 aerial photographs from a mountainous area (~3500 - 4000 m.a.s.l), from 1956, 1965, 1977 (no metadata, no camera parameters, scanned white and black). My study catchment is relatively small (1 ...
0
votes
0answers
61 views

Plotting the DEM into QGIS 3.10 from the CSV through SAGA

I had troubleshot with creating a DEM in QGIS SAGA, using this example: https://www.geodose.com/2018/09/how-to-create-dem-elevation-profile-qgis.html When I filled up the box as per below: I get an ...
0
votes
1answer
21 views

Pixel Size field in gdalinfo command meaning

What is the meaning of the Pixel Size field in the gdalinfo output on a TIFF image? I have 2 images, one is a PAN image (size 400MB) while one is a DEM (size 25MB). Both are in TIFF format. When I ...
3
votes
2answers
232 views

DEM sources for arctic regions

Are there any 90m DEMs out there for regions north of where the SRTM dataset ends? I looked at ASTER, but it seems to have a lot of unfilled voids, and it's important that the resolution matches the ...
3
votes
4answers
14k views

Why is my DEM in ArcScene flat, not 3D?

I am working with Digital Elevation Models in format TIFF 2km * 2km. As far as I know DEMs should have a 3d function but in my case the DEMs are flat. They only look 3d because of the hill shading. ...
0
votes
0answers
17 views

Incorrect slope values for points in QGIS [duplicate]

I'm trying to determine the slope of sampling points in QGIS 3.4, but the values are all ~89.99°, which I know is incorrect. Pretty sure it's an issue when creating the slope raster. Based on the ...
0
votes
0answers
56 views

Automating DEM duplication using QGIS

Context: I've imported a DEM of residential composed in several buildings. I've identified the max height of buildings by addind points in a layer for every building. Then I've integer an attribute ...
0
votes
3answers
951 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 ...
1
vote
1answer
75 views

Create polygons from raster with only a selected amount of features (not each pixel a different polygon)?

I am trying to convert a raster into different polygons. The raster is based on a DEM and only contains three classes (each pixel has value 1, 2 or 3, obtained by using the raster calculator). I want ...
1
vote
2answers
36 views

How to substract 2 dem.tiff rasters through GDAL?

I'm a beginner in GDAL and don't understand the logic of it work completly. I have a folder with 2 DEM-tif files and I need to do this: gdal_calc.py -A D:WORK\gdal\dem05.tif -B D:WORK\gdal\...
1
vote
2answers
243 views

Resampling Raster

So I was thinking about a method that would allow me to essentially get the same resolution as a 3 meter DEM but with the size of a 30 meter DEM. As most GIS people know, 3 meter DEMs tend to be ...
4
votes
2answers
4k views

Min and max values not correctly calculated for DEM using QGIS

I'm working with DEM in QGIS and need to know the min and max values of my data. In the Properties window, under the Metadata tab, the statistics section shows such values. However, I usually find ...
1
vote
0answers
34 views

Generate point of view (POV) image inside Digital Surface Model (DSM) or 3D City model

I'm currently working with DSMs (Digital Surface Models) and user perspective inside that model. I'm looking for a Python library, which lets me generate a specific view (from the POV perspective) ...
3
votes
1answer
62 views

Obtaining slope and aspect for points in QGIS

I'm new to QGIS. I have GPS points uploaded to QGIS and a ⅓ arc-second DEM (USGS) of the area. I'd like to generate slope and aspect data for each point. What is the best way to do this? The ...
4
votes
2answers
734 views

How to speed up raster2pgsql?

I'm trying to upload a 37 GB raster dataset to PostGIS. The raster is out-of-db (-R option), so the actual pixel values are not stored in PostGIS. I'm using this command: raster2pgsql -s 25833 -C -I ...
34
votes
3answers
45k views

Creating DEM from contours in QGIS?

I have a shapefile with contours and their heights. Is it possible to make a DEM from contours in QGIS without using GRASS? I found Creating DEM from contours using ArcGIS Desktop? but the answer ...
4
votes
1answer
61 views

Getting 2 point features with max/min ID from each group with same value in two fields

I'm working in QGIS for a Digital Terrain Model. I've got a table with point features, arguably vertices extracted from multipart iso-curves because the features are provided with a "vertex_par" ...
-1
votes
2answers
62 views

Fill a sink with a known volume of water to obtain actual depth and extent of a pond

Using ArcMap 10.7 I have a raster with sinks in a terrain that I developed by processing a DEM dataset. Each sink has been delimited and turned into a polygon too, and its total volume was ...
1
vote
1answer
659 views

Generating Canopy Height Model (CHM) with Quick Terrain Modeler?

I currently looking forward to process LiDAR point clouds (forest data) using Quick Terrain Modeler (QTM), but is it possible to create Canopy Height Model directly using the software?
4
votes
3answers
125 views

Using QGIS polygonize tool to create discreet slope polygons

I am trying to create a shapefile with polygons representing areas of different slopes. I am running into some problems using the following workflow. I start with a digital elevation model and using ...
5
votes
3answers
322 views

QGIS 3.10 Creating a DEM from CSV

I have been fighting with this for a week or so. I believe I have viewed the related questions on stack exchange, tried some of the suggested solutions that seemed appropriate and have found none ...
0
votes
0answers
39 views

Creating DEM from contour or point shapefiles in QGIS [duplicate]

I'm trying to make a DEM tiff file from elevation shapefiles that I have in QGIS. I have both contour shapefiles and XYZ-point shapefiles but I can't seem to make the DEM. I've tried using SAGA but ...
0
votes
1answer
24 views

Can't join multiple DEMs using QGIS 'Build Virtual Raster' if they span 2 CRS's

I have 20 odd DEMs downloaded from https://search.asf.alaska.edu/ (ALOS PALSAR) Location is the Falkland Islands. Here is an example just adding 2 of the tiles into QGIS which differ in terms of ...
1
vote
0answers
37 views

Overlap of two images is switched

I try to find a way to create DEM model for two overlapping images from different sources. The upper image has transparency of 50% and as you can see they don't quite overlap correctly. The ...
0
votes
1answer
57 views

Converting stream definition threshold to extract drainage network to metric scale?

I extracted two drainage networks from a DEM of 30 meters resolution with two stream definition thresholds: 1000 pixels and 500 pixels. Can you tell me what this thresholds represent in terms of ...
1
vote
1answer
1k views

Adjusting Z Units on DEM

I am learning how to use Arc Hydro and attempting to change the Z Units because I get a warning message saying the Spatial Reference Doesn't Match. The DEM was in Meters, and I adjusted the Z Unit ...
-2
votes
1answer
40 views

ArcGIS 10.X - DEM raster creation - Point to Raster vs. Terrain to Raster tools [closed]

I have a bunch of LiDAR data that I need to make a raster DEM & DSM from. From what I can gather my options are use the Point to Raster tool directly on the Multipoint feature or make a terrain ...
1
vote
4answers
2k views

Exporting slope raster for entire country in GEE

I have loaded SRTM (30m resolution) DEM data through Google Earth Engine and have determined the slope for the entire country of Peru. When I export the image out into Google Drive, I get the ...
2
votes
1answer
152 views

Line of Sight between sets of two points each

So I have a list of points with their longitude and latitude (Lon_A, Lat_A and Lon_B, Lat_B). I also have a DEM layer from the SRTM for the relevant location. I need to check if line of sight exists ...
10
votes
2answers
1k views

Generating DEM from isolines and spot heights using GRASS?

I have two shape files containing height information of a certain area and I need to create a raster DEM with GRASS using them. file 1 consists of height information in contours (isolines) file 2 ...
2
votes
0answers
18 views

Exctract DEM by list of vertex with GDAL

How can I generate a DEM of an area given the vertex list of the polygon that includes it? What I want to achieve is similar to the output of gdalwarp, eg: gdalwarp -t_srs EPSG:4326 -te x_min y_min ...
1
vote
0answers
133 views

Creating high resolution DEM file from points (path) in google earth using QGIS?

I am having trouble trying to create a DEM file from points in Google Earth. I followed all the steps to export a .kml from Google Earth to then import a delimited text layer that I turn into a .shape ...
1
vote
0answers
115 views

Raster map not found error with r.fill.dir

I am new the GIS world and I am having trouble with generating depressionless DEM from lidar elevation data. I am using GRASS 7.6.1 and QGIS 3.4.12. I have used r.fill.dir successfully on a ...
6
votes
1answer
13k views

The following layers were not correctly generated. Grid

I keep getting the same error: The following layers were not correctly generated.GridYou can check the log messages to find more information about the execution of the algorithm I saw two ...
6
votes
1answer
27k views

How to find the number of raster bands?

I have downloaded a 7.5 min DEM . Now while I am trying to mosaic them it gives me an error saying "Input and target dataset should have the same number of bands" . How can I figure out the number of ...
0
votes
0answers
231 views

Merge DEM TIFF grids and get average value

I have two different DEM grids (basically single-band GeoTIFFs) and I want to merge them. The grids overlap and have different values, and I want to create a new DEM grid that takes the average or ...
2
votes
0answers
62 views

Is there a way to create a DEM that follow the point cloud so you don't need to clip the DEM after?

I would like to create a DEM from an XYZ file (gridded 0,25x0,25) with 0,25 cell. I'm wondering if there is a way so that my interpolation follows my point cloud, instead of covering a rectangle like ...
2
votes
0answers
65 views

Correcting slope of river bed on DEM using QGIS or ArcGIS

I have a DEM that has incorrect value of altitude/slope in the river bed area. This is a result of the interpolation of elevation value that are close to the river and creates lots of errors. In fact ...
0
votes
0answers
186 views

Slope calculation with GDAL

I compute a slope raster in percentage and then a slope raster in degree from the same DEM with a precision of 5 meters. Why my percent slope raster has a maximum value of 110% (+ 45 °) while my ...
3
votes
1answer
119 views

Convert LiDAR GPX to DEM in QGIS?

I'm a water resources engineer with literally zero GIS experience. I'm working as a volunteer on a Engineers Without Borders project delivering safe drinking water to a remote community, where my team ...
2
votes
1answer
45 views

How do I convert an elevation shapefile into a CSV file with its XYZ data?

I am new to using QGIS and LeapfrogGeothermal Modeling. I have a shapefile for Elevation and Altitude data and need to extract XYZ coordinates out of it? Can I do that? and how? and what kind of file ...
0
votes
0answers
41 views

How do I add elevation data to a shapefile in the attributes table?

I'm using ArcGIS to create a DEM/DTM for a viewshed analysis. I have an existing DTM created from UK OS Terrain 5. I'm attempting to add the elevation data to the UK OS Open Map shapefiles for ...
0
votes
1answer
42 views

Adding building/woodland elevation data to existing OS Terrain 5 DTM in ArcGIS Desktop [closed]

Would someone be able to give me the stepped process showing how to add building/woodland elevations to an existing DTM raster in ArcMap? I seek this in order to prepare a surface model for a ...
0
votes
0answers
31 views

Creating seamless/uniform topography with multiple raster tiles?

I have multiple elevation raster tiles of an archaeological site and it would be extremely useful for me to visualize the topography as one 'uniform' image/layer. I have attempted to merge the rasters,...
1
vote
2answers
69 views

Finding date and time of Digital Elevation Model

I downloaded a DEM from the Copernicus site. I can provide the link: https://land.copernicus.eu/imagery-in-situ/eu-dem/eu-dem-v1-0-and-derived-products/eu-dem-v1.0?tab=download I would like to ...

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