A note on custom texture/FM sizes

Judith on 19/11/2008 at 15:26

As you all know, the textures put in PCTextures and/or Textures folder and used in your mission are "baked into" the ibt file. It's kinda hard to get a decent material quality without using 1024 textures, which adds to the filesize awfully. Texture compression doesn't really help that much, and it can have serious impact on image quality (ugly gradient or transparent textures, blocky normalmaps, etc.). Seems like hammering out a compromise is out of our reach. Is it?

First, let me show you three images, and you'll try to tell me what's the difference (except the shot angle ;) )

One:
(http://img90.imageshack.us/my.php?image=t3mainreleaseversion200rr1.jpg)

Inline Image:

http://img90.imageshack.us/img90/3151/t3mainreleaseversion200rr1.th.jpg

Two:
(http://img221.imageshack.us/my.php?image=t3mainreleaseversion200zb0.jpg)

Inline Image:

http://img221.imageshack.us/img221/1219/t3mainreleaseversion200zb0.th.jpg(http://g.imageshack.us/thpix.php)

Inline Image:

http://img221.imageshack.us/images/thpix.gif

Three:
(http://img230.imageshack.us/my.php?image=t3mainreleaseversion200sr9.jpg)

Inline Image:

http://img230.imageshack.us/img230/6765/t3mainreleaseversion200sr9.th.jpg(http://g.imageshack.us/thpix.php)

Inline Image:

http://img230.imageshack.us/images/thpix.gif

Well, the answers are:
1. Diffuse texture is 1024 x 1024, normalmap is 1024 x 1024
2. Diffuse texture is 256 x 256, normalmap is 1024 x 1024
3. Diffuse texture is 128 x 128, normalmap is 1024 x 1024

It happens so, because normalmap is a source of details for the diffuse image, which is quite blurry itself - it acts merely as the color base for the material (well, looks like it's called colormap by some texture artists for a reason ;) ). The normalmap is resized to fit the diffuse image scale and that's why the details look crisp.

For best results, leave your normalmap uncompressed (I know, 3mb per such file is a pain). Also remember that your normals should be really good, i.e. one-pass nVidia filter might be not enough. Use Crazybump or multi-pass technique, (http://www.cgtextures.com/content.php?action=tutorial&name=normalmap) such as this.

Feel free to experiment with this, hopefully it will help decreasing your FM size.

Judith on 19/11/2008 at 19:06

A small clarification though, apparently this technique is best when used with bricks and such regular shapes. Irregular ones, like grass look quite awful, even some diagonal tiles aren't that perfect. You can see the division line below (256 texture on the left, 1024 on the right).

(http://img233.imageshack.us/my.php?image=clipboard01ot4.jpg)

Inline Image:

http://img233.imageshack.us/img233/8594/clipboard01ot4.th.jpg(http://g.imageshack.us/thpix.php)

Inline Image:

http://img233.imageshack.us/images/thpix.gif

Ok, last test. Regular bricks again and the difference isn't that big. So, it's not a breakthrough but might be useful.

(http://img80.imageshack.us/my.php?image=clipboard01wh5.jpg)

Inline Image:

http://img80.imageshack.us/img80/2596/clipboard01wh5.th.jpg(http://g.imageshack.us/thpix.php)

Inline Image:

http://img80.imageshack.us/images/thpix.gif

ShadowSneaker on 19/11/2008 at 23:19

Thanks Judith. It will be good to know when I cook my first IBT file.
That first floor texture looks awesome.

SS

Judith on 20/11/2008 at 07:03

Hopefully that's just a start, SS :) For some reason imageshack shrunk the images, so use right-click to save, and view those in a full size.

I found that the biggest quality loss is noticeable when the light is cast vertically on the surface, for normals are barely visible in such case. 256 texture will look blurry, but you can use 512 - the difference won't be that big, even on some irregular surfaces. Still it means shrinking the average texture twice, but does it mean substantial shrinking the ibt file size? We'll have to check that too ;)

[Edit]
I did a tiny test: built 3 rooms, and used 4 custom materials for walls. The high-res version got 1024 textures and normals everywhere, while lower-res version had 512 textures and 1024 normals accordingly. The difference between the ibt file sizes was over 2 mb, so not that much (a bit more than 512 kb per material) :) It wasn't a full-size mission, so it's hard to say about the real impact it might have. I'll try that with my mission in progress some other time.

Judith on 20/11/2008 at 18:09

Ok, surprisingly I had a few hours to spare today, and I was able to check it thoroughly. I changed most of 1024px textures in my FM to 512px, and the difference was about 33 mb less (over 10% of overall .ibt file size). After compressing both files with Zip the difference decreased to 21 mb. So I guess this trick can hardly be called "a remedy" for huge FM sizes - if you aim for the highest quality I wouldn't worry about texture size :)

ShadowSneaker on 20/11/2008 at 18:59

I suppose 10% difference isn't that great but it could be useful if you have a limit to how much you can download per month (do people still have that these days?) or for hosting.

SS

Judith on 21/11/2008 at 13:29

Maybe hosting in Europe might be bit more restrictive (in Poland, in fact, is), but hosting in US offers great possibilities. I could host fanmissions on my texture site and it would hardly exceed the monthly quota :) It's not that I needed that, it's just the standard option :)