[GIS] Setting the same min/max for multiple raster layers QGIS

demqgis

I have 268 hgt-files from Viewfinder Panorama that I'm using to create an elevation model, but each of the files has its own min and max-value in Layer Properties - Symbology - Band Rendering.

Currently it looks like this:

I found I can set the min and max of each layer manually, to get an uniform scale, but this is a hassle for all 268 layers. So I was wondering if I'm missing an option somewhere, or if im doing something completely crazy?

Best Answer

You could build a virtual raster. Go to Raster - Miscellaneous - Build virtual raster, select all rasters as input, uncheck "Place each input file in a separate band":

Then change symbology of the virtual raster.

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[GIS] Min and max values not correctly calculated for DEM using QGIS

By default, QGIS does not calculate the full range for a raster. The range it calculates by default is 2% - 98%, see the 'Cumulative count cut' option in the 'Load min/max values' section of the dialog box. This is just the first option, which is why (I suspect) it is the default.

To get the full range, choose the option below it marked 'Min/max', then select 'Full' for Extent (default) and 'Actual (slower)' for Accuracy (the default is 'Estimate (faster)'). With these options all selected, click the 'Load' button at the bottom of this section of the dialog box. This loads the statistics and you will see them appear in the min max boxes in the appropriate part of the dialog box (depending on whether you are generating a single-band grey or pseudocolor palette).

[GIS] Using Arcpy, how can I determine min and max elevation from a raster DEM layer within the current extent

Use Get Raster Properties, specifically the MINIMUM and MAXIMUM values.

In theory, this code should make a temporary raster layer using the display extent -- although I have not tested it, and am not sure whether it will work -- and then the raster properties tool will apply to only the raster currently shown in the display.

import arcpy

arcpy.env.extent = arcpy.mapping.MapDocument.activeView.Extent

MakeRasterLayer_management("c:/temp/raster.tif", "rlayer", "#", arcpy.env.extent)

# Get the geoprocessing result object
elevMinResult = arcpy.GetRasterProperties_management("rlayer", "MINIMUM")
# Get the elevation minimum value from geoprocessing result object
elevMin = elevMinResult.getOutput(0)

Best Answer

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[GIS] Min and max values not correctly calculated for DEM using QGIS

[GIS] Using Arcpy, how can I determine min and max elevation from a raster DEM layer within the current extent

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