New answers tagged dem
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Thanks to all the helpers out there.
Photogrammetry is what brought me further down the road.
Wiki Photogrammetry
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To read your raster into a numpy Array you can try:
import gdal
ds = gdal.Open(r'C:\path\to\raster\dsm.tif')
band1 = ds.GetRasterBand(1).ReadAsArray()
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After loading the DEM, you can use the Raster | Raster calculator menu option to modify values.
For example, here the raster 'Tsavo.dem' was loaded (it appears as band Tsavo@1), and the calculator will produce a new TIF called tsavoMinus30.tif using the calculation "Tsavo@1" - 30
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Let's say your DEM layers have the names DEM1 and DEM2.
The following expression (in the QGIS Raster Calculator) returns 0 for the differences that have an absolute value that is less than 0.005, and the calculated difference larger absolute differences:
"DEM1@1" - "DEM1@1" * (("DEM1@1" - "DEM1@1" > 0.005) OR ("DEM1@1" - "DEM1@1" < -0.005))
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This error comes from the inappropriate layer input.
First of all we must save our imported .csv layer in the .shp format. In the geometry type it would be good to include the z-dimension and select the point layer.
Then we can run the plugin and everything is fine
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After launching the QGIS 3.8.3 desktop via OSGeo instead of QGIS 3.10 I found, that everything is working.
The bug exists in some 3x versions, as described on the GitHub:
https://github.com/qgis/QGIS/issues/29346 https://github.com/qgis/QGIS/issues/30095
https://github.com/qgis/QGIS/issues/33677 https://github.com/qgis/QGIS/issues/33386
Alternatively is ...
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Try to use Profile tool which you can download from Plugin Manager. The tool can use your existing line layer to extract the profile from the raster data.
Have a look at this video: Using the Profile Tool plugin in QGIS which I selected randomly to show how to use Profile tool.
To use for existing vector layer:
Select the raster image
Add Layer
From the ...
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I have looked into the problem a while now and found a solution that suits my needs quite well. If you run the GRASS tool r.geomorphon (https://grass.osgeo.org/grass76/manuals/addons/r.geomorphon) on a e.g. an ASTER DEM with water bodies and islands the islands are usually clearly visible as slopes and peaks within the water bodie, classified as flat. I ...
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QGis is trying to be helpful by "stretching" the the "colours" of the tiles for you. The easy way around this to add all of the tiles as a single layer. This is quite easy as you can create a virtual layer so instead of this:
You can go to Raster->Miscellaneous->Build Virtual Raster, unclick place each input file into a different band and select all ...
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You don't need to create a DEM from the contours and spot heights, you can download the DEM directly. Select "ASCII Grid and GML (Grid): 162 Mb" on the OS Terrain® 50 download page.
If you really want to interpolate from the contours and spot heights... The contours do contain elevation. As per the user guide, the elevation of each contour is stored in the ...
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TRI algorithm was made according to this science paper "Riley, S.J., De Gloria, S.D., Elliot, R. (1999): A Terrain Ruggedness that Quantifies Topographic Heterogeneity. Intermountain Journal of Science".
First, you have to know which pixel size you have? If your pixel size 20x20 then you have some calculations.
TRI Riley classification is based on 1km x 1km ...
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Found a solution. Probably not the best and easiest, but it works. It also has nice side effect regarding performance!
Gdal_contour basically draws a line between all pixels with the same value. Of course it doesn't see outside the tile, how the line would continue. That's why the line isn't equal between two adjacent tiles at their border.
The solution ...
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You need points in both sides of the road to interpolate. In the process we will get also a buffer to clip the raster.
Create a buffer of your lines with a proper radius for a road (let's assume that 30m is a proper radius).
Dissolve the buffers.
Densify by interval the dissolved buffer, by a proper distance to get enough nodes (let's assume that 10m ...
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Geospatial Data Abstraction Library (GDAL) will allow you to convert many open raster file types to a USGS DEM. The QGIS GDAL processing toolbox has a tool called Translate (convert formats). Translate (convert formats) allows you to choose USGS DEM as the output.
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The geotiff spec on geotiff.maptools.org states if you want to display a PixelIsPoint raster, the origin is shifted to (-0.5, -0.5). The "point" remains at (0,0), it is just displayed as the centre of the pixel.
If a point-pixel image were to be displayed on a display device with pixel cells having the same size as the raster spacing, then the upper-...
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Try Cross Profiles tool in the Processing Toolbox > SAGA > Terrain Analysis - Profiles.
(1) Make sure to reproject your DEM to XY(m) coordinates.
(2) Prepare your river center line(s), perhaps by digitizing manually.
(3) Start the tool and set each parameters:
DEM: Your DEM layer
Lines: Your river line(s) layer
Profile Distance: 10m
Profile ...
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I have tested the plugin and it is working fine in my machine.
One common way to download (SRTM among other) data is searching it in Earth Explorer site.
All the information about how to use the site is in their Help page.
If you want to download just that image, you can do it from the Download link provided in the following page:
https://...
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To complete other answers note that most very good hillshade seem to be created using a mix of of GIS and non GIS tool (ie. 3d rendering or image traitement tools) or some "hillshade only" specific software. So even if some really nice hillshade could be created using QGIS only don't limit yourself to a single tool
Have a look at these site : Relief Shading ...
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The key to the ESRI hillshade layer is the multidirectional hillshading, according to their blog: https://www.esri.com/arcgis-blog/products/arcgis-living-atlas/mapping/introducing-esris-next-generation-hillshade/
But otherwise it seems pretty basic.
Even just using the built in hillshade renderer in QGIS (which supports multidirectional hillshading) you ...
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I highly recommend the Batch Hillshader plugin for QGIS by PANOImagen (GitHub).
It generates a three light exposure composite using the methodology outlined in this paper:
Ref.: Gantenbein, C. (2012): "Creating Shaded Relief for Geologic Mapping using Multiple Light Sources". U.S. From "Digital Mapping Techniques'10--Workshop Proceedings". Geological Survey ...
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Problem solved in plug-in 2.4.1
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