Celestia Forums

Texture Bugs

I just discovered a fascinating phenomenon with certain texture(s) that I initially thought was a bug in Celestia. While trying to replace certain JPEG textures with their transparent .PNG counterparts, I found that the .PNG's would not load. After investigating the matter, I could not find any logical reason for the failure. This lead me to investigate the textures themselves. After using several different graphics programs to view the textures, I remembered that one in particular would alert me if the file extension was incorrect. I loaded the PNG into the program (which supports DDS, PNG and virtually every other extension), but again could find no reason for the load failure. I decided to RE-save the texture (a fix for problem, web, graphics I inadvertantly discovered a while back) under the PNG extension. While saving the graphic, the program gave me the option to save the original transparencies which, of course, I checked off.
Though the textures did not show signs of corruption, re-saving them to their original format did the trick and now they load properly.

The program is Irfanview. It's free and can be found here:
http://www.irfanview.com/

Post Script: The texture discrepancy may have occurred during the download process or may have originated on the server. The point is that there were no outward manifestations of it at any time. If you have a problem texture, try this and see if it works!

That's EXACTLY what I have been doing...

I've had this problem with the Black Hole jpeg, and the new colored versions of the Deimos and Phobos textures. Seems that PhotoShop may be the culprit, but I'm not sure.

Thanks for letting others know that I'm not nuts when I tell an author that there's something wrong with the textures. Still don't know what the problem IS, but the FIX is a simple re-saving of the file in either jpg or png formats using IrfanView.

Take care, Bob

Yeah it sure was wierd Bob. I found the fix quite accidently and just on a "let's see what happens if I do this" basis. My laptop has a bad habit of placing the .JPE file extension on images instead of the more common .JPG tag. If I don't remember to change it before saving the image, it won't open up properly in some graphics programs. When I tried to open a texture in Photoshop, (on a different computer that doesn't share the image save problem) the program alerted that it did not recognize the file extension (even though it told me the extension was .PNG!), a file association that is supported by Photoshop. I don't know how to explain the phenom. Maybe seldon, Grant or one of the others can elaborate. I not sure this fix will be the answer for every properly tagged image that fails to load, but it worked for me.

Oh rats! I forgot to log-in...
That was my post above Bob. Sorry about that!
I checked the option for Auto Log-In, but it doesn't work for me all the time.

I'm by no means a texture expert, but here's a question that might help narrow down the possible problem. Are you guys opening the files into an image editor directly from your web-browser, and then saving them to disk, or are you downloading them straight to disk?
If you're doing the first, then it's possible your image editor is altering the file format in transit, and the solution would be to download the files straight to disk without ever opening them. If you're doing the second, then it's some hardware/OS/driver incompatibility specific to your machines, since others aren't having the problem.

Maybe you've thought of this already, but I thought I'd mention it.

Grant

Grant,

I'm downloading straight to disk, and I'm beginning to think that my problem is specific to my machine. (See the topic "At Selden's Request" elsewhere in this forum.

I'm also having graphics problems with Celestia 1.3.1Pre11 that never occurred using 1.3.0. Does anyone here know about DirectDraw vs OpenGL, and whether the use of both on my machine could be causing problems?

Thanks, Bob

That's a good question Grant! I'll have to keep my eyes on that.
Sometimes I save the image to disc after it loads in my IE browser's default viewer and sometimes I right click the link (w/no image visable)and save target as...
I have never used any other graphic program in the actual download process.