All Questions
2,351 questions
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43
views
Adding two layers (raster and DEM) together in QGIS Graphical Modeler
I'm making an algorithm in the modeler, and I got stuck. I need to add two layers together. I have a raster layer (which used to be a vector layer, but I transformed it) and I also have a DEM layer.
...
- 11
0
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0
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27
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Conversion of TIFF DEM in XYZ
I have this problem (QGIS 3.28): I have created a DEM in another program (RAS Mapper of HEC-RAS), starting from a bathymetry and adding some simple structure on it. I have exported this modified DEM ...
1
vote
1
answer
95
views
Display French survey DEM in QGIS
[QGIS 3.40, Windows 11, although I faced the same problem with many previous versions]
I'm trying to display -and use- the (otherwise excellent) DEM supplied by the French survey (IGN). My attempts so ...
- 546
0
votes
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answers
72
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Calibration LiDAR derive DEM for flood inundation risk map
I need to create a flood model based on a LiDAR-derived Digital Elevation Model (DEM). However, I am encountering an issue:
The line dividing the DEM into two parts shows that the right side is ...
0
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0
answers
20
views
Setting model height for .stl output in QGIS (DEMto3D plugin v3.6)
I'm running QGIS 3.28 and 3.34 with DEMto3D v3.6 plugin and I'm not able to figure out the Model Height settings to create a proper .stl model. Everything seems backwards and upside down and sometimes ...
- 1
1
vote
1
answer
45
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R terra Flow Accumulation resulting raster with DN = 1
I encountered problems in calculating flow accumulation using terra::flowAccumulation() from lidar-based DEM. I've inspected the visual and general properties of the DEM and flow direction rasters, ...
0
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42
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COPERNICUS/DEM/GLO30 in Google Earth Engine
I'm having an issue with Google Earth Engine. I'm attempting to download .csv files of COPERNICUS/DEM/GLO30 elevation data at specific latitude & longitude points (n=266). The code below works for ...
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28
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The SAGA "Real surface area" tool outputs a raster with impossible band values
I want to know the real surface area of my polygon in a mountainous region.
I use these steps: https://www.youtube.com/watch?v=EzqwEs9OkJ4
I downloaded the DEM from https://search.earthdata.nasa.gov/ -...
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0
answers
37
views
TIFF Raster to a Geodatabase
I have downloaded a bare earth DEM which is stored as a TIFF file.
I am trying to add my DEM to a geodatabase (using raster to geodatabase tool) but I am receiving the error message :
Failed to ...
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1
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1
answer
58
views
How can I rasterize a vector object, while keeping it's height value?
It's a simple building, with a height of 60 meters.
I tried using the vector-raster tool, but I ended up with a 40 GB object(?), that won't show up on the map. And then I used TIN interpolation (...
- 13
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answers
56
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How to identify upstream/downstream flow of streams with respect to a point?
I have water streams data and point data of certain treatment plants along those streams (two separate files). I need to know whether the stream is upstream or downstream from each of those treatment ...
1
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1
answer
38
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How to save raster as int16 / compressed using SaveGDAL from richdem
I am using the python package richdem to calculate a slope map from my DEM file.
dem_file = richdem.LoadGDAL(os.path.join(output_dir, f'DEM_{region_name_clean}_EPSG{EPSG}_resampled.tif'))
slope = ...
- 25
0
votes
0
answers
46
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Analysis of conflict between directional Radio an Wind turbines in QGIS 3.34
I have a directional radio track from point A (x,y,z) to point b (x,y,z). The directional radio shall be 3D-buffered (restriction area) to create an oval around the directional radio, similar to a ...
- 129
0
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0
answers
44
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How do I find the footprint of the 1 Meter USGS DEM in a vector format?
I want to know, for a given bounding box, if 1 Meter USGS DEM data is available.
At the moment I am querying:
https://tnmaccess.nationalmap.gov/api/v1/products?bbox=-119.94995,39.10144,-119.9442,39....
- 141
2
votes
1
answer
70
views
DTM and DSM from the same LAZ file - extent do not match
I'm trying to extract tree tops, and I have successfully processed dozens of LAZ files with R, but I have a problem with one.
als_dir <- "C:/Users/bzzzzzzi/Documents/dummy/KRON86/09/"
als ...
0
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0
answers
61
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Understanding calculation of slope
I'd like to make a calculation on the slope of house-roofs.
So I have a DEM and drawn a polygon that will mask the raster. This is the side of the roof I want to have an average of, to find out how ...
- 558
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0
answers
30
views
Adding a Shapefile to a water mask made from a DEM file
I created a water mask from a DEM File. But there are no lakes and rivers on this water mask. I want to add some lakes and rivers to it. I tried to do this with Shapefile but I couldn't merge them. ...
- 37
0
votes
1
answer
49
views
Split shapefile according to DEM file boundaries
As you can see in the image, the shapefile extends outside the DEM file. How can I split the shapefile to fit the DEM file boundaries exactly?
I will use this DEM file as a water mark. So the ...
- 37
0
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0
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25
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Lake reconfiguration suitability using ArcGIS Pro
I need to score floodplain lakes based on how easily/feasibly they could be reconfigured or if they need to be removed to:
Maintain lake fishing access as a whole through the whole valley (ie. if a ...
- 1
0
votes
1
answer
47
views
Creating DEM from LiDAR on ArcGIS Pro [closed]
I'm currently trying to create a DEM out of LiDAR data. According to various tutorials, you have to create pyramids on the .las file and then perform a ground classification. The problem is that the ...
- 135
1
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0
answers
50
views
Blender DEM Visualisation
I am experimenting with new GIS tools, and one of them is Blender. I am trying to visualize a DEM, and everything works fine, except for the strange contour-like stripes appearing in the DEM. I’m not ...
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1
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0
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31
views
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 ...
- 11
1
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0
answers
34
views
Opening .img file created in Erdas Imagine 2023 in Erdas Imagine 2022
I am having an issue working with a file created in Erdas Imagine 2023 in Erdas Imagine 2022. I ran a tool with the output .img. However, the .img format seems to be different in Erdas 2023 vs Erdas ...
- 11
1
vote
0
answers
52
views
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 ...
1
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0
answers
34
views
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 ...
- 11
2
votes
1
answer
63
views
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 ...
- 21
0
votes
1
answer
37
views
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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0
answers
36
views
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, ...
- 83
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0
answers
14
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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. ...
- 1
0
votes
1
answer
40
views
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 ...
1
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1
answer
52
views
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 ...
- 11
0
votes
0
answers
24
views
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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1
vote
1
answer
220
views
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. ...
- 37
0
votes
1
answer
78
views
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 ...
- 81
2
votes
0
answers
96
views
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 ...
- 71
0
votes
1
answer
92
views
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 ...
- 637
1
vote
0
answers
66
views
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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1
vote
0
answers
45
views
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. ...
- 65
0
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0
answers
42
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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 ...
1
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1
answer
464
views
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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0
votes
1
answer
98
views
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?
1
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1
answer
359
views
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 ...
- 11
0
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0
answers
78
views
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 ...
0
votes
1
answer
64
views
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 ...
0
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0
answers
66
views
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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1
vote
1
answer
59
views
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 ...
- 89
0
votes
1
answer
49
views
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 ...
- 85
4
votes
1
answer
506
views
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?
- 69
-1
votes
1
answer
36
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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 ...
- 25
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votes
0
answers
33
views
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 ...
