Update with potential solution:
Remaining problem: Exported “Location Snapshot” is of significantly lower quality than desired, which effects the final edited terrain image.
I had limited success with the following steps (RESULT: Projects photoshop edited terrain texture onto existing Location Terrain, but source is of low quality)
- Used this mostly: Projecting image over terrain - #7 by Geo
- Took Location Snapshot texture, showed hidden geometry, selected each section individually, right clicked, Combine Texture. This output a single combined texture of the Location Snapshot (what I wanted!) that was of significantly lower quality than the source imagery (not what I wanted!).
- Took this saved .jpg, scaled it up in GIMP/Photoshop, edited the texture as necessary, and saved a new .jpg.
- In SketchUp, duplicated the Location Snapshot plane by ctrl+moving up above the existing Location Terrain. Right clicked, made texture unique. Edited this new texture/material, replaced it with the higher resolution edited texture I made.
- Projected the image down onto the location terrain: Hid hidden geometry, double clicked Location Terrain to make it ‘editable’ and it grayed out the flat plane with the desired texture above it, used the paint tool to sample the gray texture and apply it to the mesh terrain anyway.