GTOPO30
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GTOPO30 is a digital elevation model for the world, developed by USGS. It has a 30-arc second resolution (approximately 1km), and is split into 33 tiles stored in the USGS DEM file format.
[edit] GTOPO30 "makeTER" for 16-bit DOS systems
By using the 30 arc-second GTOPO30 data set, it is possible with special software algorithms (such as used by Fiko Software in DWPRaster version 1.70), to decrease the original 16-bit colours used by GTOPO30 to colour palette that fits 8-bit colour developments as used for instance in 16-bit DOS or Linux programs.
It is also possible to increase the GTOPO30 data set to i.e. 15 arc-seconds by software algorithms, by doing elevation predictions between four 30 arc-seconds points and in this way predicts the shape of mountains etc.