All the illustrations and figures shown in these pages are original and were created at NCAR. They were generated using a combination of NCAR Graphics, custom PostScript, and information on orbital tracks and viewing swaths from Sea Space's Terascan software package.
The general approach was to use NCAR Graphics'
ezmap utility to
generate the basic maps to be used. Somewhat unusually, each portion
of a map (e.g. latitude-longitude grid lines, continental outlines,
perimeters, color fills, etc.) were generated separately. These
portions of the final figures were then converted to PostScript using
ctrans.
The individual portions were then combined using
a simple custom PostScript binding. Special effects, such as the
color blending used on the individual geographical coverage maps for
the geostationary satellites, were generated directly using PostScript.
Color choices were edited using PostScript and all labels for the
illustrations, including the Chinese, were generated directly in
native PostScript code. This approach resulted in a PostScript
graphics file for each figure that could be easily edited for special
effects and which permitted options not easily created using NCAR
Graphics alone. The extended plot of the geographical
coverage of geostationary satellites, for example, is not directly
supported by ezmap.
The transparency effect used to show the satellite viewing swath was
also generated using custom PostScript code to modify the output from
ezmap.
These custom PostScript figures were them converted to GIF format
using a local NCAR script, ps2gif.
This script makes use of the ghostscript PostScript interpreter to convert
the image to "nrif" format, and then via other utilities (i.e.,
imconv) on to a standard "gif" format.
Although this is a bit convoluted, it seems to work pretty well. The
only obvious errors are the occasional small failures in the transparency
effect in the final "gif" files. If you look closely at the previous
figure you can see some small vertical lines that break up the transparent
effect. The PostScript version of these illustrations worked flawlessly.
It may be necessary to edit these graphs by hand using some sort of "gif"
editor to clean them up, although this isn't going to be a high priority
on my part. For now, at least, this route makes it difficult to incorporate
transparent "colors" in the figures, making it necessary to set the background
page color to white. It would also be desirable to modernize the "gif" files to
support interlacing.
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