Crevice/dirt map generation

poopinmymouth

I've been trying to integrate Crevice maps into my next-gen process. I am having a hell of a time finding a good workflow for this using either Maya, max, or a cheap third party program (no lightwave or XSI). It needs to respect intersection objects (something quickdirt for max doesn't do), and be a true Crevice map generation, not a hack or trick preferably. Something akin to Zbrush's crevice map generation in Zmapper, but that will work on multiple objects of various polycounts being baked onto an arbitrary low.

Anyone have any good solutions they care to show?

I'm going to try playing around with this: http://www.lightengine3d.com/index2.html but it requires maya 7 or before.

Joao Sapiro

Crazybump generates cool cavity maps ! xnormal also generates something that can "help"

poopinmymouth

I assume you're referring to crazybump's heightmap generation feature, which is too soft, and not what I'm looking for. Thanks though.

Rick Stirling

Could you give us an example texture of what you'd want the output to look like? 1,000 words and all that.

poopinmymouth

Since I'm looking for the tool, I can't make an image very easily to display.

Here's something close, http://www.lightengine3d.com/downloads/plugins/curvature/testImages/a6m1.jpg from the above link. The brown areas are "crevices", but I want to find something that even respects seperate objects getting close to one another.

A good rough approximation is to take an AO bake, and run a high pass filter over it, removing all the large scale shadows, and only leaving the minor stuff (which is what I've used till now)

Rick Stirling

Ah, something like Dirtreyes used to do in max?

Rick Stirling

http://www.pluginz.com/product/12045?genre=1&category=40

I've not used it in years.

Whargoul

AO with wide spread, distance turned down and an inverse exponential falloff?

Should do the trick.

Eric Chadwick

I've found better than the highpasss is to do a gamma on the AO, tightens up the wide gradients, keeps all but the darkest bits.

Ryan Clark

Do you find CrazyBump's maps are too soft even with the "Sharpen & Flatten" slider?

If you can send me an example of what you're looking for vs what you get from CrazyBump, I'll see what must be done to match it.

thanks!

-Ryan

edit: I see you've already posted the airplane above... would you mind sending me an image of just the texture unwrapped, though?

IronHawk

Has anyone ever found a way to use a displacement map like This with RTT?

Joshua Stubbles

You're killing me here with the "crevice maps" thing. It looks exactly the same as AO/GI/Radiosity, you name it. What is so different about "crevice maps" that it deserves yet another name?

Rob Galanakis

[ QUOTE ]
You're killing me here with the "crevice maps" thing. It looks exactly the same as AO/GI/Radiosity, you name it. What is so different about "crevice maps" that it deserves yet another name?

[/ QUOTE ]

It doesn't take shadowing/light into account, like an AO map does.

http://boards.polycount.net/showflat.php?Cat=0&Number=178246&an=&page=0&vc=1

sinistergfx

Isn't that just an AO map with the distance turned down?

Ghostscape

Yeah I'm still not understanding what the difference between this and an ambient occlusion map is.

All an AmbOcc map does is darken areas where the normals are facing eachother within X distance, darkening all of the crevices.

If you invert it you get a nice mask for all of the crevices that you can use to fill the crevices with dirt and stuff. That's what I've been doing at work and at home ever since I started baking out AO.

poopinmymouth

I'll have to play around with the Mental Ray AO bake, since I'm not seeing any distance modifiers in the max light tracer options. I think reducing the distance might work, never tried it. Thanks for the suggestions.

Just as an alliteration. In a crevice map, your legs won't shadow each other just because they are close, but you'll still get all the small scale contrast from the pants overlapping the legs, wrinkles, shirt over hanging the pants, etc. Basically you get the lighting that's almost never "wrong". A wrong example would be arms with shadows on the undersides from facing the torso, but you've rotated the arm straight forward and it's still dark underneath.

MoP

I do like Crazybump's method, feed it a normal map and it outputs a very cool map (with Sharpen & Flatten at 97, since 99 produces weird noisy artifacts), which has "raised" edges highlighted and crevice edges darkened. Useful for overlaying onto spec maps to pick out the highs and darken the cracks.

FatAssasin

"Max Dist." (in the AO shader of the RTT window, or "Max Distance" in the AO material itself) is the parameter you're looking for. The default of "0" means infinite rays, change it to some small percentage of the overall size of your objects and you'll get closer to what you're looking for.

You can also try playing with the "Spread", which will give you tighter or more diffuse shadows (smaller numbers = tighter shadows).

katzeimsack

use cavety masking in zbrush 3 and bake the colormap in xnormal

poopinmymouth

From Whargoul:
[ QUOTE ]
AO with wide spread, distance turned down and an inverse exponential falloff?

Should do the trick.

[/ QUOTE ]

From FatAssasin:
[ QUOTE ]
"Max Dist." (in the AO shader of the RTT window, or "Max Distance" in the AO material itself) is the parameter you're looking for. The default of "0" means infinite rays, change it to some small percentage of the overall size of your objects and you'll get closer to what you're looking for.

You can also try playing with the "Spread", which will give you tighter or more diffuse shadows (smaller numbers = tighter shadows).

[/ QUOTE ]

This is exactly what I needed. Thanks Whargoul and FatAssasin.

*edit: Here's an example,

Joshua Stubbles

The picture explains it all, thanks.
Although I'll just keep calling it Ambient Occlusion :P

Whargoul

@ Erik - yeah gamma on the map works, which is similar to the inverse exponential falloff thing I was talking about. Usually, you can adjust the falloff speed - so that a point %50 of the way to the distance limit is %50 shaded, etc. You can make the falloff exponential, so only very close stuff is shaded, or the reverse - it shades darkly almost right up to the limit. Which is nice for crack stuff, set the distance low, and set the falloff power low (so it does a "root" to the colour - similar to gamma correcting it down) and you get really dark cracks with no inter-object shading.

Blaizer

That's like an AO pass ¬¬

For the AO, instead of using a black, try using a soft grey. AO can be adjusted in PS also if you can't choose the color.