Comparing the Onscreen Picture in Doom 3’s Quality Modes
We took a series of screenshots in different quality modes of the game to look for any discrepancies in the image quality as provided by GPUs from NVIDIA and ATI.
Graphics Cards from ATI
Graphics Cards from NVIDIA
There’s no practical difference between the Ultra High and High Quality modes. You can only discern it looking at the screenshots in turns. On a close inspection, there are color patterns in the second screenshot, which are due to diffuse and specular maps compression, but they are very inconspicuous even on static screens. During the game, searching for any compression artifacts is a sure way to an immediate death of your hero J. Besides that, most of the game levels are too dark to allow noticing so small a quality loss.
In the Medium Quality mode, you can already see the specific square-shaped artifacts, most visible on small details of a scene. This is a tradeoff of the normal maps compression. The quality of the textures hasn’t become worse much in comparison to the High Quality mode, but they look blurry, especially in the distance, due to the lack of anisotropic filtering. Besides that, there are compression-related artifacts on complex textures – the same color patterns.
All these visual defects are also present in the Low Quality mode, but the texture quality goes down, too, due to the reduction of the resolution. Defects caused by compression of textures and normal, diffuse and specular maps are more visible on blurred textures than in the Medium Quality mode. In this mode, the game can hardly please you since many smaller details are simply lost, and all the texts, hieroglyphs, and pictures on the walls become shapeless smudges. It looks like a game of the year 2000 at best, rather than of 2004.
The difference between the images as provided by graphics cards from NVIDIA and ATI is really small, and mostly noticeable in light locations, which are very rare in this game. You can see them well enough in the second screen that shows a brightly lit passageway with numerous recesses. This difference is probably due to the specifics of the two realizations of anisotropic filtering, since you don’t see it in the Medium and Low Quality modes where AF is disabled by default.