[mapserver-users] GTOPO30, Raster Maps, and Projections

[Frederik Ramm]

Hi,

   I'm using MapServer 4.3 (but will upgrade to 4.4/4.5 if required to
solve my problem).

I have a PNG map of Europe, generated from GTOPO30 elevation data. I
created it using the free "drawmap" utility; the file is 1920x2540
pixels in size and depicts the area from (30N,10W) to (70N,20E).

As far as I understand, drawmap doesn't really use a proper
projection, it just stretches the grid to match whatever coordinates
and pixel sizes I specify.

How can I use this PNG bitmap as a raster background for my MapServer
maps? I have read the relevant documentation and got "something"
to show up but I am at a loss how to create a proper world file for
the data I have. The docs say:

"The world file contents look like the following. The first
coefficient is the X pixel size. The second and third are rotational
coefficients (and should normally be NULL). The fourth is the Y pixel
size, normally negative indicating that Y decreases as you move down
from the top left origin. The final two values are the X and Y
location of the center of the top left pixel."

This seems to imply that I need a bitmap in which the pixel size (in
meters) is constant - something which cannot be said of my map!

If this is too difficult, then is there some other way to use GTOPO30
data with MapServer (besides creating raster files with drawmap and
taking it from there)?

Thanks,
Frederik

-- 
Frederik Ramm  ##  eMail frederik at remote.org  ##  N48°59.94 E008°24.36'