Gray map to normal map error (nvidia filter)

grihan

Hi all
I have a problem when I try to make a ramp in my normal map, I use a gradient in my gray map, but when i convert it to normal map, there is noise in that part. I can avoid it using a 16bit-channels image for the gray map, but...do you know another trick to avoid the noise?

Here is an example:


Alberto Moreno "Grihan"
http://www.grihan.com

Eric Chadwick

You could turn off dithering in your gradient tool, but you're still going to get artifacts like banding. No way to avoid this with 8-bit source.

Think about it, only 256 levels of gray. If you have a 256-wide bitmap, and you fill it with a 0-black to 255-white gradient, then there should be no dithering or banding.

But if you do the same with a 127-gray to 255-white gradient, then the software has to lay down 128 levels of gray across 256 pixels... if there's no dithering then you get banding. It gets worse the shallower your color range, and the wider the gradient.

16-bit or higher is the way to go. But even then you won't get a good normalmap out of linear gradients, the slope is not curved. You need a biased gradient instead. Better to generate from geometry.

Joao Sapiro

or you quickly model that that wont take more than 1 minute :P