What are the best Image files to use ?

[Darkmiss]

out of all the image files

What one would be the best to use for the planet textures,
to make Celestia run as smooth as posible ?

I know JPG's are slow decompressing

But what about dds, bmp, png, or tiff ?

and what would be there good and bad points, for this program ?

[chris]

out of all the image files

What one would be the best to use for the planet textures,
to make Celestia run as smooth as posible ?

I know JPG's are slow decompressing

But what about dds, bmp, png, or tiff ?

and what would be there good and bad points, for this program ?

Here's a quick summary of the pros and cons of the various formats:

DDS
Advantages:

Uses least texture memory on graphics cards (8x less for DXT1)
Fast loading
DXT3/DXT5 formats support an alpha channel

Disadvantages:

Big files on disk
Doesn't work on older hardware (pre-GeForce, pre-Radeon)
Some textures may exhibit compression artifacts

JPEG
Advantages:

Smallest file size (= quick downloads)

Disadvantages:

Slowest to load
No alpha channel--won't work for cloud and ring textures

PNG
Advantages:

Supports an alpha channel

Disadvantages:

Lossless compression, so files tend to be very large

[Darkmiss]

Thanks Chris, I understand a bit more now

Wow you guys on this forum, have some real talent.
sometimes the way you guys talk about graphics, sounds like another language to me..

[Rassilon]

chris wrote: Some textures may exhibit compression artifacts

hmmm might explain the squares I am getting when compiling 1024 x 512 texes using dxt3 compression....Has anyone messed with the compression values yet? not the formats mind you but the values of compression...Suppose its a job for me if not

[Troy]

Chris, would it be feasible to allow Celestia to parse .ssc files in a format-agnostic manner? For example:

Texture "venus.*"

I'm developing an 8k texture. Anyone who can run an 8k texture should be able to handle DDS images, so I plan to use that file format. However, I also plan on creating a 2k version of the texture for those who can't use the bigger version. It stands to reason that many of the people who choose the 2k version have older video cards, and therefore they can't use the DDS file format. So I'll need to make it a PNG or JPG.

Wouldn't it be nice if all users could just drop the same code into thier .ssc file and have it work? Or even better, what if you wanted the DDS in the highres directory and the PNG in the medres directory? You couldn't do it. Your .ssc file would have to specify one or the other. IMHO this somewhat cripples the whole concept of keeping seperate texture directories, because the texture's size is a key factor in what image format is used. ( alpha channel being #2 )

Of course, I'd also like for users to be able to drop in replacments for solar system bodies without editing anything, but that's for another post.