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Daz
10-30-2003, 02:21 AM
hmm, the new features of mental ray such as its excellent support for displacement maps looks good.

Has anyone out there tried using it for details on a human, such as creating the ear with a displacement map so you dun have to do the hole complicated job of modelling it, sure it may not look excellent for those ultra-realism freaks, but generally in a scene with a hunded million lights and fast moving characters, would you be able to tell if some one used displacement for say, (trimmed) finger nails, ear grooves, belly buttons, the grooves in your teeth, moles, muscle viens, you get the point. Does it work well for any of these? especially ears?
peekoot
10-30-2003, 08:07 AM
sorry to dissapoint you.. but i really don't think you could do that with displacements.... and here's why:

diplacement you can see as mathematical function... wich means one grayscale value turns into one vertex position... ear shape is all twists and turns and at some places you would need one grayscale value to turn into 2,3 or even more vertex positions...

displacements just can't do it.... i'm affraid you will have to model it... :)

you would get unreasonably high polycount anyway...

i suggest you to start with simple ears on your characters... as you advance you will feel more comfortable to make more realistic ones... the good thing is that ears are quite similar on every person... they follow the same pattern... so in most cases you will get away by modifying one premodelled ear... ;)

hope this helps...

cheers...
EricChadwick
10-30-2003, 02:40 PM
I agree, would be difficult to pull off. You might get it to work if you have a simple donut-like extrusion there with the displacement map on it to refine the ear. Problem is though that you would want to extract the displacement map from an actual ear model in the first place. Might work though, but would take a lot of fiddling I think.
coffeepenguin
10-30-2003, 04:05 PM
I supose you could take a grayscale image of an ear use it as a displacement map, then convert it to a mesh and play with what you get.
sevenfingers
10-30-2003, 07:50 PM
I wouldn't bother with it... First, you'd need something better than Max default displacements... ie PRMan or something. (Final render has micro triangle displacement, but I haven't tried it).

The thread made me curious though, so I made some tests... thanks goes out to metagons.com for the free model that I butchered to get the source ear.

http://www.radarteam.se/muf/ears.jpg

Again, if fast moving and lots of effects.. just do a low poly ear and texture it well. Don't bother with displacements. They'll tax your system to the max because of the brute force approach Max has with displacements.
EricChadwick
10-30-2003, 08:06 PM
That's cool!

What if you try generating the height map from the high-res ear by using the normals/UVs from the low-res ear? Via something like Mike Bunnell's tool (http://www.seanomlor.com/mikeb/). I would think that would give you much better displacement results. Not with the scanline renderer, but VRay/brazil/whatever supports sub-pixel displacement.

I see the benefit being chiefly a reduced cage complexity for animation purposes.

Anyhow, just guessing here. I don't do any of this kind of rendering, I'm just a real-time 3D guy.
sevenfingers
10-30-2003, 08:13 PM
well, the picture and my post wasn't worded well...

That was exactly what I did posm :)

I did not have the possibility to do any subpixel displacements though, and the low res geometry would most likely displace better if it was closer in topology to the source ear.

Another thing that might be of interest is to use the new version of Zbrush in conjunction with low res cages when it comes out...

I hear it pushes insane polycounts and generates displacement maps much the same way kaldera does (by comparing low res and high res geometry).

To get even better displacement a normal map could be added, since displacement by itself easily causes faceting.
Daz
10-31-2003, 02:32 AM
hey thanks sevenfingers, what about the other things, that are generally simpler? finger nails, belly buttons, the grooves in your teeth, moles, muscle viens. I can see belly buttons having a similar problem, however what about viens, that way when you texture something youd know your scars, skin folds and viens all match up exactly with the textures?
EricChadwick
10-31-2003, 01:18 PM
Daz,

You might find some good info here...
http://cube.phlatt.net/forums/spiraloid/viewtopic.php?TopicID=581
There are many threads on that forum about using displacement mapping. One of the moderators is Bay Raitt, the facial animation lead for Gollum at Weta Digital.
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