Contents - Index


World Map Data

WXtrack uses world map data for two purposes - as a background image to the orbit display, and as a source of topographic data where the ETOPO5 database is unavailable.  The background image can be in either JPEG or BMP format, but it must have one of the following names.  Note that some unzip utilities may not handle these long file names correctly, so if you get no background on the World Map display, check that the files are present in the same folder as WXtrack.exe and are correctly named.  The names are listed in the order in which the program attempts to find the files.

UserMap.jpg
SmallUserMap.jpg or LargeUserMap.jpg   (if topography data is present)
LargeUserMap.jpg or SmallUserMap.jpg   (if topography data is absent)
UserMap.bmp

If the ETOPO5 data is present, it is assumed that the background map is only acting as a decoration, and therefore the small map has priority over the large map, as the large map image takes nearly an extra 4MB of memory.

If the ETOPO5 data is not present, it is assumed that the higher resolution of the large map and its associated memory penalty is acceptable, as the JPEG file will be the only available source of topographic data.

Note that you can always override the two assumptions mentioned above, as the file UserMap.jpg is always the first file that is loaded if present, so simply renaming or copying the large JPG to "UserMap.jpg" will force its use.  You can download higher quality background images from the WXtrack Web page if you wish.  Click to download the available files:

UserMap.jpg  --> Satellite Tools, WXtrack, Downloads  (best quality, with hill shading)
and:
LargeUserMap.jpg  --> Satellite Tools, WXtrack, Downloads  (high quality)

You can use any JPEG or BMP image you want as the background, subject to the naming convention described above.  Note that as the map projection is cylindrical equidistant (also called Plate Carree) and the area covered is 360 degrees (H) by 180 degrees (V), the map should be twice as wide as it is high.  The supplied map is 1800 pixels wide by 900 pixels high.  Some Windows 9X systems may be unable to handle bitmaps bigger than the screen width.
Recently, NASA's Earth Observatory have made some very striking cloud-free earth images available as part of their Blue Marble project.

ETOPO5 Data

WXtrack can use the National Geophysical Data Center (NGDC) ETOPO5 5 minute data file for ground path prediction if the file etopo5.elev is present in the same folder as the program executable.  This will not affect the World Map display, just the ground path prediction.  This data file may be obtained from the Internet, for example:

  http://www.ngdc.noaa.gov/mgg/global/relief/ETOPO5/TOPO/ETOPO5/
or:
  www.geol.binghamton.edu/faculty/jones/etopo5.zip

Be warned that this zip file is an 11MB download that expands to 18MB when unzipped.  But the results _are_ worth it.  NGDC can supply the data on CD-ROM (product code 1093-A27-001).  I am advised that the price is around $100 or online ordered $75, plus $11 shipping and handling, plus for outside the US a currency charge of $10.  The product number is G01093-cdr-A0001 and the e-mail address is pkd@ngdc.noaa.gov, the URL is http://www.ngdc.noaa.gov/mgg/fliers/93mgg01.html.


Why should I download the ETOPO5 data?

The predicted picture quality on the Ground Path and Flight tabs can be substantially enhanced by downloading higher resolution topographic data than that supplied with the program in the *UserMap.jpg files.  The backdrop on the World Map tab will not be affected, only the Ground Path and Flight tabs.  The highest resolution data supplied with the program is at 12 minute intervals, and is compressed with JPG resulting in artefacts.  If the image quality is adequate for you, then you do not need the higher resolution data.  However, using the ETOPO5 5 minute data will increase the number of pixels in the predicted image by about 5.6 times, more when you consider that it is not compressed.

Is higher resolution data supported?

No, neither the 2-minute or the 30-second datasets can be read by WXtrack.  In any case, their resolution exceeds that of the satellite images.