str8g8 on 16/12/2005 at 11:18
A quick note to anyone generating their own normal maps: if like me you have used the nvidia normal map filter in photoshop to generate normal maps from traditional bump or height maps, you may have noticed some odd effects in flesh, namely, the bump effect being inverted in some places, yet looking correct in others, depending on the light source and angle etc.
I have found that inverting the red and/or green channel in photoshop can often correct these problems. It seems that although there is no standard way for a game (or a shader etc) to interpret the data contained within normal maps.
I have also recently discovered (
http://pixologic.com/home/home.shtml) zbrush, which together with the new zmapper plugin, is becoming an industry standard. You can download a demo - it's a very strange hybrid but amazing once you get into it's mindset.
cheers
str8g8
OrbWeaver on 16/12/2005 at 12:50
If the bump map is inverted in some places and not others, then swapping channels will not help (it will just invert ALL of the normal maps, i.e. making the already-inverted faces correct but inverting the correct faces).
The inverted normal map is a known editing issue, which I always managed to solve by selecting the face and setting the texture alignment to Planar (although some people reported that this did not work for them).
Ziemanskye on 16/12/2005 at 13:34
Zbrush is a brain melter.
:(
It's also probably quite good, and I know it was used on HL2, and given the quotes on their page I also suspect in UT2k7/Gears of War. I don't have time right now to play with it, but it is a very weird package.
As a general thing though, I think it might be fair to say that it's kind of like Maya's paint deformation tools when used on a really finely sub-divided surface. Much less of a system hog than Maya though, which is good. (I haven't found if Max has an equivalent, largely because of not looking if they're there)
str8g8 on 16/12/2005 at 14:26
Quote:
If the bump map is inverted in some places and not others, then swapping channels will not help (it will just invert ALL of the normal maps, i.e. making the already-inverted faces correct but inverting the correct faces).
That's just it, it did help! It didn't seem to be related to problems with bsp and texture alignment, as changing the direction of the light could fix or create the problem ... Also, I didn't mean swapping the Red and Green channels with each other, I meant inverting the channel itself (ie. image > adjustment > invert). Anyway, if anyone experiencing the same problems, it might be worth a try.
Regarding zbrush, it is similar in principle to polygon scupting in maya (and similar tools in max 7) but is several orders of magnitude faster and more responsive. I have had no problem editing meshes of 2 million polys + in zbrush! But yes it is a brain melter! :) Largely because it is not a true 3d package (it describes itself as 2.5d) and because of the "funky" interface design.
However, once you get into it's way of doing things, it is wonderful to work with. I am considering putting together a wiki tutorial on it if there is enough interest.
OrbWeaver on 16/12/2005 at 14:51
Quote Posted by str8g8
That's just it, it did help! It didn't seem to be related to problems with bsp and texture alignment, as changing the direction of the light could fix or create the problem
If the normal map is inverted then it will appear to be illuminated from the direction
opposite the one the light is coming from, so moving the light is very likely affect the apparent inversion of the mesh. Are you sure it was the case that the normal map was actually inverted, as opposed to looking different from what you expected due to the lighting?
str8g8 on 16/12/2005 at 15:15
Quote:
Are you sure it was the case that the normal map was actually inverted, as opposed to looking different from what you expected due to the lighting?
I
was :erm: but now I am not so sure ... I will experiment some more and maybe post screens to show what I mean.
str8g8 on 19/12/2005 at 10:18
ascottk: that's a good tutorial :) maybe you should make it into a wiki page? Or link to it from a page. Possibly there needs to be a page on there for creating normal maps. I was thinking of doing one for zbrush in particular ...
orbweaver: you were right! some bsp surfaces (and some of my smeshes to confuse things even further) had flipped uvs, planar mapping surfaces fixed things. Thanks for your help!
