16-bit vs. 32-bit vs. 32-bit 2X Lightmaps

ffox on 29/9/2012 at 14:34

I don't have grep but can get similar results with (http://www.fileseek.ca/) Fileseek.

voodoo47 on 8/10/2012 at 05:59

not completely done testing yet, so consider this preliminary, but anyway - it seems like old ati gpus (DX9c and older) are not able to display relit levels properly. the issues are very small with plain 32bit, but painfully obvious with 32bit x2. so careful, if you relight your level with 32bit x2, you could be making the life a bit unpleasant for all those from the ati camp who have not boarded the DX10+ ship yet.

(http://imageshack.us/a/img404/6700/32bitx2borked.jpg)

Inline Image:

http://desmond.imageshack.us/Himg404/scaled.php?server=404&filename=32bitx2borked.jpg&res=crop

The Watcher on 8/10/2012 at 09:18

I can only suspect that's a driver issue, or maybe a card issue - I'm running DX9c on WinXP with a GF7900GS, and I've just relit Xavier's with 32x2 lighting, and I have no problems...

voodoo47 on 8/10/2012 at 09:31

will try on a gf7600 to see whether this is radeon exclusive. but the point stands - one should probably stay with the "safer" plain 32bit, at least for now.

Yandros on 9/10/2012 at 03:28

I recently reverted from 32 2x to 32 on Drymian Codex. The reason? I have dropped in a few high res replacement textures, and I noticed with higher res textures you get a lot more overbright washout around light sources. It actually looked pretty bad in my opinion.

sNeaksieGarrett on 13/10/2012 at 16:34

I'm not sure I quite understand the whole difference between 32-bit versus 32-bit 2X.. :erg:

However, it seems to me that 2X makes things a bit too bright? In the comparison shots from the (http://www.ttlg.com/forums/showthread.php?t=140086&page=4&p=2144160&viewfull=1#post2144160) other thread, the one light fixture comparison with 32-bit/32-bit 2X showed a big glowing disc around the 32-bit 2X light fixture, whereas the regular 32-bit lighting didn't have that around the light fixture.

That seems like a significant change, and I'm not sure which one would be better to use, but it seems like regular 32-bit is better.

ZylonBane on 13/10/2012 at 16:42

As has been explained, it allows lightmaps to overbrighten textures. Normal 16/32-bit lightmaps can only darken textures. Overbrightening is a common technique in HDR and faux-HDR rendering.

Overbrightening in Giants: Citizen Kabuto:

Inline Image:

http://pcmedia.ign.com/media/reviews/image/giants002.jpg

Angs on 14/10/2012 at 19:17

Quote Posted by sNeaksieGarrett

With both 32-bit and 32-bit 2X you have a glowing disc around light sources, regular has large and dim discs, 2X has small bright discs. First pic: discs, second pic: overbrightening

Inline Image:

http://i.imgur.com/Dr0tD.png

Inline Image:

http://i.imgur.com/S01EF.png

(http://www.wolframalpha.com/input/?i=Plot%5B%7BFloor%5B15.99*Min%5B1%2F%281%2Bx%5E2%2By%5E2%29%2C0.5%5D%5D*0.5%2CFloor%5B7.99%2F%281%2Bx%5E2%2By%5E2%29%5D%7D%2C%7Bx%2C-3%2C3%7D%5D) Here are some plots to visualize what happens (the colors are not equivalent between different plots, z-axis values are.)

And a visualization of possible light levels (with ~1/16 of the actual levels shown):

Code:

X <- fully bright
16-bit # #
32-bit ##############
32-2X # # # # # # # # # # # # # #
^^^^ overbright

In my opinion 2X makes light sources look more alive, for lack of a better word. Perhaps realistic, because the regular lightmaps look so flat compared to real-life lights. They actually lighten the place up, instead of merely not darkening it. :) Because of the overbrightening you just have to be careful with light backgrounds, because then you hit the roof when the lightmap is applied to the texture.

sNeaksieGarrett on 14/10/2012 at 20:04

Thanks for the replies. I read the thread previously but found it hard to follow/understand. Also, having those comparison shots up close of the light fixture really helps, thanks Angs.:thumb:

Yeah, I can see that it adds what you guys are calling an overbright feature around the light, which to me seems too dramatic, but I guess I don't understand real world light as well as I thought I did. 32-bit lighting seemed more visually pleasing to my eye than did 2X I guess.

I like the gradual increase of light over a wall in bigger rings around the light source, rather than the small overbright disc around the light, at least in the comparison shots on the left. On the close up shots, it actually looks like 2X has the disc whereas the 32-bit does not. :confused:

Albert on 14/10/2012 at 21:07

Overbright might be handy in some situations though. For instance, a hot desert in the middle of nowhere. :cheeky:

I also think it would work to the advantage of FMs with sparse lighting that is trying to evoke a macabre feel. Overbright purple lamps, y'know?