ossim-dem

ossim-dem is a command line application used to generate elevation products from raw dem, dted, and srtm data. This application supports 2 basic functions: hillshade and color-relief. From these 2 operations you can create the following products.

Color Relief

Color Relief is used to generate an RGB or ARGB representation of a dem. Different colors are used to represent elevation bands. Users will provide a template with corresponding colors values.

ossim-dem --op color-relief --color-table template.kwl --srs EPSG:4326 
input.src output.jpg

There is a color relief template on:

 http://trac.osgeo.org/ossim/browser/trunk/ossim/etc/templates/ossim-dem-color-table-template.kwl

Hillshade

Hillshade is used to generate a shaded relief. It requires the following inputs:

• Sun Azimuth
• Sun Elevation
• Vertical Exaggeration
• Color (either RGB or Color Table)

Example:

ossim-dem --op hillshade --azimuth 270 --elevation 45 --exaggeration 10
--color 222,229,188 --srs EPSG:4326 input.src output.jpg

Example with color table:

ossim-dem --op hillshade --azimuth 270 --elevation 45 --exaggeration 10
--color-table template.kwl --srs EPSG:4326 input.src output.jpg

Additional Parameters

ossim-dem shares many of the parameters used in orthoigen including:

• writer-props
• resample-type
• thumbnail
• srs

It accepts a comma delimited list of input files or a .src file. The output file extension is used to determine output format. As with orthoigen, users can specify a writer to use with a -w argument.

SRC File

The src file used by ossim-dem is nearly identical to the one used by orthoigen. The primary difference between the 2 is the use of the dem keyword to distinguish elevation data from imagery data. Example:

image0.file: C:\my_image.ntf
image0.entry: 2
image0.ovr: D:\support_dir\images\my_image.ovr
image0.rgb: 3,2,1

dem0:file E:\N38W123.hgt
dem0.entry: 0
dem0.ovr: D:\support_dir\dems\N38W123.ovr

dem1:file Z:\N37W123.hgt
dem1.entry: 0
dem1.ovr: D:\support_dir\dems\N37W123.ovr