Celestia Forums

I have a nice Mollweide Projection that I would like to use (eventually as a cloud map) as a texture in Celestia.



This image was downloaded from the Space Science and Engineering Center from the University of Wisconson-Madison website.

I have read Selden's "Creating Textures for Celestia" where it describes how to obtain software that can convert images to the Simple Cylidrical or "Plate Carre" Projection. My first attempt, using the Spherical Mapping Corrector from Richard Rosenman, yielded the following image:



As you can see South America and Australia are distorted.

Before I spend too much time on the trial-and-error process, could someone please tell me how I may acheive a successful conversion?

Thanks-

Exactly where did you get the image (what Web page) and where is its format documented?

It's distorted because it's not Mollweide, it's Hammer-Aitoff.

Here's the output from mmps when using the script

convert -geometry 1024x512! 098.png tmp1.ppm
./project -i hammer -w 1024 -h 512 -f ./tmp1.ppm > tmp2.ppm
convert tmp2.ppm tmp2.jpg

The website where this image was downloaded is:

http://www.ssec.wisc.edu/data/composites.html

It is a global infrared compsite image which represents the cloud cover on April 4th, 2007 at 00:00 GMT.

I just called it Mollweide because of the image in your "Creating Textures for Celestia" document looks very similar:



Thanks for the info and I'll give the mmps a try.

Although they have similar outlines, the projections are rather different.
Here's what Hammer-Aitoff looks like:

I am getting the message:

"Unexpected number of colors"

when I run the "project" line of the script you gave me for MMPS. I have tried to convert the image to 8-bit palleted but got the same message. I am using the exact same file (098.png).

any suggestions?

I use the 8bit version of ImageMagick.
Too many programs can't handle the output of the 16bit version.
Reducing the pallette is not sufficient. It still writes 16bit data per color plane.