Extracting perfect bump maps

Kingblue

Problem: the photo of a wooden beam, despite being hi-res (474 x 4968 ) gives me an ugly bump map when I render from a close point of view.
I'm using Max, Vray, and Cs4 to extract bump maps.
The procedure I'm using now is to isolate the green channel, and apply it as a bump map.
The artifacts I see can only be sweetened, but not corrected, playing with levels.
Wondering if I'm using a good method or if it's just the texture limit that can't be avoided.

cryrid

The green channel in an image would very rarely (if ever in a photograph) represent the same data that a bumpmap would use, so it's probably not a method to use if you're looking for 'perfect' bumps.

The rest of it could be due to whatever compression you happen to be using on the image format.

Mik2121

Yeah, unless I'm missing something, there's absolutely no reqason to use the green channel of a photo for part of the bumpmap. What you're doing is simply using the green light information of the photo.. so if you have a green spoon and a red spoon, going to the green channel would give you absolutely different results even if the spoons were the same.

You'd do better using the full image and giving it some nDo pass or xNormal, and try to play around with the results.

Kingblue

Thanks.