transparent hillshade cooking guide using gdal

hillshade-transparent-overlay.md

Ingredients

• a decent DEM
• gdal
• some computer

compute grayscale hillshade using gdaldem

gdaldem hillshade -compute_edges you_dem_file hillshade.tif

In another bowl, prepare the following shade.ramp file:

• first value is the hillshade grey level, 220 is the value for flat areas
• 2nd, 3rd, 4th value are the output RGB components (0 0 0 = black)
• last value is the alpha channel: 255 = opaque, 0 = transparent

0 0 0 0 255
32 0 0 0 240
64 0 0 0 180
96 0 0 0 120
220 0 0 0 0
221 255 255 255 0
255 255 255 255 192

#other option (smoother shades) 0 0 0 0 255 220 0 0 0 0 221 255 255 255 0 255 255 255 255 192

#and third one if you want only shades 0 0 0 0 255 220 0 0 0 0 255 0 0 0 0

stir together using gdaldem color-relief

gdaldem color-relief hillshade.tif -alpha shade.ramp hillshade-overlay.tif

It would be awesome if you could include some output examples. Thanks for the info!