Does anyone know what causes this detail reveal effect?

Guest · Post by **Guest** » Thu Aug 20, 2020 10:46 am

Hello,

I'm curious if anyone knows what creates this effect in Ultimate Doom.
https://www.youtube.com/watch?v=4W1JaWE ... e=youtu.be
As the Doom Guy moves down the hallway things appear to get brighter with him which I'm assuming is just the textures around the player get painted at varying brightness based on distance from the player. But the textures also seem to reveal strange new details as he gets close and become primitive at a distance. Is this mimapping? Or just some strange relationship between the textures and lighting? If anyone has some details I'd love to hear them.

wildweasel · Post by **wildweasel** » Thu Aug 20, 2020 11:17 am

That is light diminishing coupled with the original 256-color palette. As rooms get darker, the palette is pretty much running out of colors it can use to smooth out transitions between light levels.

Guest · Post by **Guest** » Thu Aug 20, 2020 12:53 pm

Interesting. Just to clarify because I'm trying to learn about this stuff but am still a beginner. The palette is limited to 256 colors and the room is being dynamically lit as the player moves around. So, when you're point blank to the wall you're seeing the texture in all of it's original glory but when you're backing up the artifact-like coloring you see as it's darkening are the limited color palettes attempts to make "smooth" transition to an unlit wall?

wildweasel · Post by **wildweasel** » Thu Aug 20, 2020 2:36 pm

Sylvia Derringlack wrote:Interesting. Just to clarify because I'm trying to learn about this stuff but am still a beginner. The palette is limited to 256 colors and the room is being dynamically lit as the player moves around. So, when you're point blank to the wall you're seeing the texture in all of it's original glory but when you're backing up the artifact-like coloring you see as it's darkening are the limited color palettes attempts to make "smooth" transition to an unlit wall?

Yes. Visual aid:

This is the original Doom palette. If, say, your wall texture uses colors 64 through 79 for a nice, detailed brown wall, those 16 shades of brown are all shown correctly at full brightness. But as the room gets darker, and the player stands further away from it, the brighter shades are gradually eliminated from it, and the Colormap starts to substitute brighter shades with darker ones. Because it's gradually using fewer colors, the wall begins to lose its sense of depth, and details become all but invisible. By the time the room is at its darkest, the wall may only be showing 2 or 3 shades of brown.

Guest · Post by **Guest** » Thu Aug 20, 2020 3:28 pm

Got it. That visualization is very helpful. Much appreciated!

leileilol · Post by **leileilol** » Thu Aug 20, 2020 10:10 pm

Yeah, palette degradation from shading lookup can lead to a certain 'aesthetic' allowing your mind to fill in more detail at a distance, and also prevents some mild pixel popping of certain details (kind of like a mipmap-like effect when shading is applied to wide-luminance-ranged detailed textures)

(also for every argument for this, there's always a 6+ paragraph essay on the merits of hardware ability for maximum image quality against it)

ZDoom