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General / Re: How to reduce size of generated DEM geotiff
« on: February 10, 2023, 04:07:13 PM »
Thanks for bringing up this discussion!
As far as I understand it, the DEM geotiff basically stores a 32bit float value for every "pixel".
An Ortho in contrast has 24bit per pixel (8bit for R, G, B each + sometimes alpha) - but orthos can be compressed with extremely efficient lossy codecs like jpeg(XL) or webp.
The DEM in contrast can only be compressed losslessly.
In order to save more space, it would be amazing to have the option to store the data in half-precission 16bit-floats for example. Or even quantizise further down and map it to 8 bit integer.
Actually JPEG XL could also be the solution here...
It allows an arbitrary number of channels 1 to 4000+ and each of them can have either binary or integers and floats up to 64 bit. It also allows lossy compression even on floats...
As far as I understand it, the DEM geotiff basically stores a 32bit float value for every "pixel".
An Ortho in contrast has 24bit per pixel (8bit for R, G, B each + sometimes alpha) - but orthos can be compressed with extremely efficient lossy codecs like jpeg(XL) or webp.
The DEM in contrast can only be compressed losslessly.
In order to save more space, it would be amazing to have the option to store the data in half-precission 16bit-floats for example. Or even quantizise further down and map it to 8 bit integer.
Actually JPEG XL could also be the solution here...
It allows an arbitrary number of channels 1 to 4000+ and each of them can have either binary or integers and floats up to 64 bit. It also allows lossy compression even on floats...