Relief shade

Creating a relief shade using GDAL & DEMS

• 8M DEM of NZ - lds:51768
• GDAL

Create a VRT of all the imagery

gdalbuildvrt dem/*.tif dem.vrt

Create the relief shade

gdaldem hillshade -co COMPRESS=lzw -co TILED=yes -co NUM_THREADS=ALL_CPUS -of gtiff \
     -z 1.3 -az 315 -alt 60  -compute_edges \
     dem.vrt dem.hillshade.tiff

Apply colors to the relief shade

gdaldem color-relief -co COMPRESS=lzw -co TILED=yes -co NUM_THREADS=ALL_CPUS -of gtiff \
    -co ALPHA=YES  -alpha \
    dem.hillshade.tiff color.ramp dem.hillshade.color.tiff

Color ramps & Vector tiles

Relief shading with vector tiles the only imagery operation is "overlay", if any white exists in the relief shade it lightens the image

Base Image:

gdaldem hillshade:

Using default color ramp applys whites

Custom color ramp which only applys the darken

nv      0       0       0       0
0       0       0       0        255
170      0       0       0       64
220      0       0       0       0
255      0       0       0       0

nv - No value or NO_DATA set full alpha