Hi John:
Because there are others who may be trying to learn how to make Blend Masks in GIMP as well as in other graphics applications, this info is a good start.
But, I'd like to derive more information for the FS development knowledge base from this, and your other threads.
Gray-scale values end up in the Blend Mask image file is read as '
Data' by SDK Resample via a Gaussian method.
If we identify in
ex: GIMP, what RGB=x,x,x gray-scale 'color' values allowed the underlying aerial image of the 'Sand Spit' that is partly covered by the Straits of Georgia ('water shallows') to "
show through to the top" of the custom aerial imagery land class BGL, IIUC, regardless of the actual graphics applications one uses, we can establish a better understanding of what Gray-scale values to use for a relatively predictable result in a similar scenario.
Likewise, if we identify in
ex: GIMP, what RGB=x,x,x gray-scale 'color' values allowed the underlying default land class textures and associated Autogen vegetation annotations to "
show through to the top" of the custom aerial imagery land class BGL, IIUC, regardless of the actual graphics applications one uses, we can establish a better understanding of what Gray-scale values to use for a relatively predictable result in a similar scenario.
Could you please load up your final Blend Mask into GIMP, and take some readings of the pixel gray-scale values for the 2 above scenery feature areas of interest that I inquired about ?
GIMP docs on how to display the RGB color values for pixels under the cursor position:
https://docs.gimp.org/en/gimp-pointer-info-dialog.html
https://docs.gimp.org/2.2/en/gimp-view-info.html
Thanks in advance for providing some additional info to assist others with these types of tasks in the future.
GaryGB