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I have an RGB elevation raster from a seabed. This raster is interpolated from points which I also have access to. I don't want to download all points and do an interpolation myself. Now the problem is the interpolated raster is only containing RGB values and no elevation. I want to add those values in a new band using (hopefully) only a small portion of the points. In other words; can i derive the elevation from the rgb values using some samples easily? Preferebly in qgis and maybe some python. Why? So i can change the colours to my wishes and maybe visualize it in 3D

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    No you can't get elevation from RGB, it's impossible to tell what renderer or scale was used. If you have access to the points that made it do the interpolation yourself, I can help talk you through the process in QGIS. – Michael Stimson Jul 3 '17 at 0:01
  • Thanks, I can do an interpolation myself but the only problem is that it based on millions of points.. why isnt it possible, is RGB just roo random? – Willem van Opstal Jul 3 '17 at 6:01
  • Not random, rendered, there is no way to tell what the minimum, maximum and correlation of stretch which is handled differently by GIS packages.. even within a package the stretch could be min-max, standard deviation etc. The colour ramp could be HSV or RGB etc, single or multi modal - there is just too many unknowns. Is there millions of points within your AOI? if possible you can subset to your AOI + a small amount outside to avoid edge artefacts; millions of points should take a few hours, at worst overnight, depending on your workstation specs. – Michael Stimson Jul 3 '17 at 20:59
  • can this be of any help? I sampled a lot of points resulting in this graph; depth is along the horizontal axis: i.stack.imgur.com/6D6Lb.png – Willem van Opstal Aug 14 '17 at 10:21

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