About the Maps

What software was used to make the maps?

They were produced using a software package call GMT (Generic Mapping Tools) written by Paul Wessel and Walter Smith. This mapping package is described in their announcement "Free Software Helps Map and Display Data" which appeared in EOS, Trans. Amer. Ge ophys. U., vol. 72, pp. 441,445-446, 1991. The GMT program can be downloaded from the server at the University of Hawaii. We've used the GMT software on a Hewlett Packard 735 work station. The output of running GMT is a postscript file. This was converted into GIF form using one of the commands supported by a graphics conversion program called Image Magick. The GIF was expor ted to a Macintosh Computer, where it was converted to Macintosh specific PICT format using software called Graphic Converter. Once the image is in PICT format, then MacDraw Pro was used to add enhancements like station names and scale bars. After modific ations, the file was saved as PICT and reconverted to GIF for use in these pages.

What topographic data base was used?

The topographic and bathymetric data used came from the 5 minute by 5 minute data set called TerrainBase. It is a global data set which for most of the world gives fairly reliable relief features. One will note, however, that unusual square or rectangular "plateaus" exist in this data set which are clearly in error. For example, in the lower right hand corner of the map of Europe, one will see such a feature in Saudi Arabia. The TerrainBase data set can be purchased from the National Geophysical Data Center.

Mark Torrence Mark.H.Torrence.1@gsfc.nasa.gov
Raytheon Information Technology and Scientific Services Corporation

Responsible NASA Official: Ben Chao
Original Web Implementation: John W. Robbins

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