- changed status to resolved
VRT Band Math algorithm
Issue #839
resolved
Since QGIS 3.22, the QGIS Raster calculator can store results as VRT. Unfortunately, this calculator can’t be used to execute Numpy / Python code.
The VRT Band Math algorithm should allow to do so, by using VRT Pixel Functions:
https://gdal.org/drivers/raster/vrt.html#using-derived-bands-with-pixel-functions-in-python
Compared to the existing, and more powerful Raster Math algorithm, VRT Band Math is limited due to some restrictions of VRT Pixel Function:
- each band is calculated individually
- inputs required for different bands may be read multiple times (maybe system IO caching helps)
Despite of the drawbacks, VRT Band Math can be very efficient for on-the-fly visualisation of indices like NDVI, EVI, Tessaled Cap, etc.
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resolves
#839→ <<cset eebf9b927812>>