Wikimaps Atlas : Shaded relief v.05/03

6 Shaded Reliefs

Action: When run, this country.makefile [download][1] the raster GIS DEM sources, process them (unzip, crop, shaded relief, resize, colorize), to output 6 elegant shaded reliefs. Can work for any country or area, given you provide WNES (West/North/East/South) geocoordinates, in decimal degrees.

Output:

• 2 hillshades:
  • hillshade_grey (GIS tif)
  • hillshade_trans (png)
• 1 color-relief (wikipedia style):
  • color+hillshade_000pc (GIS tif)
• 3 mix (for comparison):
  • color+hillshade_050pc (jpg)
  • color+hillshade_100pc (jpg)
  • color+hillshade_multiply (jpg)

For similar data and similar px dimensions, file sizes are .tif:5.0MB, .png:1.6MB, .jpg:239KB. Also, whenever possible and relevant, we use the lighter format.

Direct command:

make -f country.makefile ITEM=India WEST=67.0 NORTH=37.5  EAST=99.0 SOUTH=05.0 WIDTH=1280

Parameters: Derivated from man gdal and man convert.

• Z= (zFactor, integer >0, default 5): vertical exaggeration used to pre-multiply the elevations
• AZ= (azimuth, integer [0-359], default: 315): azimuth of the light, in degrees. 0 if it comes from the top of the raster, 90 from the east, … The default value, 315, should rarely be changed as it is the value generally used to generate shaded maps.
• ALT= (altitude of light, in degrees, integer [0-90], default 60): altitude of the light, in degrees. 90 if the light comes from above the DEM, 0 if it is raking light.
• FUZZ= (fuzzy selection, integer [0-100], default 7): colors within this distance are considered equal
• SHADOW= (integer [0-100]) opacity of the hillshade upon color-relief.
• WIDTH=… (in px, default: 1280) : width of the bitmaps (tif, png). The EIGHT is conserved from WNES ratio and the WIDTH.

Note: if the input GIS raster is in feet, then s scale should be edited. See man gdal.

[1]: the download task will automatically download the ETOPO1 (342MB) archive file, which may take from few minutes to a dozen of hours, depending on your web line.

Suggestions? Drop me a suggestion/command line @hugo_lz