Creating tile cache from hillshade degrades quality of shading

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12-08-2022 03:01 PM
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PaulCone2
Occasional Contributor III

I am attempting to build a hillshade in a small, portable format for use on onboard Mobile Display Terminals on fire engines that would respond to a fire or other emergency in a hilly, forested area.  The vendor software uses ArcGIS Runtime and requires tile packages -- vector tile packages for vector data, but raster data like hillshade still is a .tpk file.  I've successfully resampled the source DEM to 5' to reduce it to a reasonable size for distribution over wifi (about 220 MB) but I having less luck getting the same image quality into the package.  The issue is not one of resolution loss (5' vs. 1' is acceptable) but rather the caching of the grayscale of the hillshade into a tile cache.  Even before it gets to the package it basically turns to mud, with loss of detail in the darker areas (before and after below)...

1ft_dem_resampled_to_5ft_hillshaded.png

5'_hillshade_tile_cached.png

I've tried adjusting gamma - no effect, modeling shadows - made it worse, adjusting altitude from 45 to 75 - made it lighter - but then caching again made it worse.  The only other idea I have is something is getting lost because it appears it's converting the grayscale to RGB but I can't find a setting to keep that from happening.  I also tried generating a tiling cache scheme using JPEG then PNG32, rather than the default of MIXED, still nothing better (no difference between any of those three).

Any other ideas here?

Paul Cone

City of Portland, Oregon

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