Scali and DeanoC hit the nail on the head, I think. Going from compressed to higher resolution compressed has probably more potential than going to uncompressed, since the latter gives only a small improvement compared to the increase in space/bandwith requirements.
Like so many people I have played around with High Quality, Ultra and DoomConfig.cfg tweaking but I could not perceive a difference in-game. In particular the pixelly appearance of textures on most geometry remained - most things look perfect if you are at least 4 metres away but if you get closer then features that are not horizontal or vertical appear pixellated. One example that is easy to check is the floor tiles on the lower level of the hangar (where shot_demo001 was taken) - the tiles a bit away from the edge. The grates close to the edge are perfect for tuning aniso filtering quality, BTW - I get a bit of shimmer/aliasing even at 16AF and it only goes away with image_lodbias 0.3 or thereabouts but I am playing with image_lodbias 1 because of the performance penalty for non-integer bias.
Setting image_usePrecompressedTextures to 1 did not result in any perceivable image quality degradation but it increased performance by 10% (56.4 fps to 61.2 fps in the timedemo). Thorough comparison of screenshots might turn up a few differences but in-game one setting appears just as good as the other, except for the smoother framerates of course. I guess that underlines Scali's and DeanoC's point - compressed textures can give the same apparent quality at higher performance, or better quality if the space/bandwith are used for higher-res compressed textures.
Be that as it may, Doom³ is perhaps not a very good example for judging the merits of compression for normal maps, textures etc. For one thing, many of the things that are normal-mapped are moving around quickly and trying to kill you. For another, other compromises like low-poly models (heads) and very low-res textures are probably more apparent/distracting in-game than the artifacts from normal compression. Last but not least, many people will have to make a compromise between playable framerates and image quality in this game, since smooth framerates are just as much a part of the perceived quality when playing a game as what might be visible in a still image.
Me personally, I hate it when framerate drops below 55 fps or so because then I see multiple copies of things when I move or turn, which I find very distracting especially during fast combat. Same for the shimmer caused by texture/geometry aliasing, although geometry aliasing is less of a factor for me in Doom³ than texture aliasing. That is why I am playing at 1280x960 2AA 16AF with image_lodbias 1, even though the bias causes slight blurring even at 16AF (if you know where to look). Some people may find this horrible - especially those that recommend setting image_lodbias to -1 or -2
- but for me it is important that the scene remains smooth and noise-free even if I turn/move. I mean, I have done things like playing Unreal in software mode and Quake2 on a Voodoo², but the fact that I was willing to suffer in the past does not mean that I am willing to suffer now.
I guess that was just a rather long-winded way of saying that artifacts which are static with regard to the geometry - like compression artifacts - may be much less noticable for some people than artifacts resulting from things like poor filtering because the latter are very apparent when moving/turning while the former are only visible upon close inspection. And even then one might have trouble telling whether things were designed this way or the result of artifacting, unless one compares screenshots.
