Displacement map question

[Shinobi]

ok,, me and a friend are trying to get a displacement map on a head,, which we will use to make a super high poly mesh for normal mapping purposes..


before anyone says anything, we dont have the 500$ for a copy of zbrush....


anyways we're trying to apply a normal map to a head model and have realised that you cannot displace inwards,,, black is zero displacement, and white is full displacement upwards!


so is it possible to do inward displacements with a displacement map? (btw we rendered in mental ray)

we expected it to work like a bump map (grey = no displacement)..


can anyone help?

 

[Lupus]

Yes you can do it, but I'm afraid I don't know how

 

[The Dark Elf]

invert the displacement. Tis as simple as that. AFAIK this works in Lightwave and Softimage, and I think Maya. Infact I'm pretty sure works in Maya

Course if you do two maps, one inverted one not. Remember they'll cancel each other out.

There are other methods too but some involve messing around with the geometry.

Personally I'd just stick with regular displacement. and take into account all the inward displacement to begin with. It's a lot less trouble in the end and does get what you need.


Btw its "anyways we're trying to apply a displacement map to a head model" not normal map, They wont displace correctly atall.

 

[Shinobi]

whoops, I meant displacement map....


and, man that sucks,,, well, time to harass the school head to get a copy of zbrush

thanks fenric

 

[The Dark Elf]

whoops, I meant displacement map....


and, man that sucks,,, well, time to harass the school head to get a copy of zbrush

thanks fenric

What app you using at the moment?

Just because I said it worked in LW, XSI and Maya doesn't mean it wont in other apps, its just I don't know those as well, it'll probably work in Max.

Honestly I've never needed to do negative displacement mapping like that though, I just plan ahead and have been ok so far *touch wood*

 

[Shinobi]

hahaha,, we just had never used displacement maps before,, and thought we could use them in the same fashion as bump maps,, unfortunately,,,

anyways it was an experiment to try and get very minute skin cracks and features,,

seems like zbrush or something that can handle a lot of polies is the way to go


I tried subdividing a mesh a ton in maya then using the sculpting tool, but it took about 25 seconds for each brush stroke to register in maya


we are indeed using max for the displacement, but we're using mental ray to render out the displacement....

well at least we tried,,


we're thinking of using a positive displacement map, turning it into a mesh then applying the negative map, or vice versa,,, but it seems like too much work and we'll be lucky if the viewport doesnt crash with a 6million poly head.....

 

[The Dark Elf]

I'd be careful applying one displacement map, saving the transformed version, then applying another, as the polygons will already be stretched to some extent from the first one, which will almost certainly jar with the second and cause poly's to pop and mess up.

You should have a go converting your mesh to NURBS in Maya, then apply your displacement maps. They do work much better with NURBS, and you only need the displacements for the moment of baking the normals and other details then thats it. An hours rendering/baking which will save days of doing it the other ways. Looks nicer too

Keep trying though, it'll hit you suddenly. ZBrush is great for organic stuff, I'd use subdivision or NURBS modeling for the rest though and apply displacement maps on it that way.

 

[Shinobi]

the guy who modelled the character has never used nurbs and has 10+ years in polies,, also time is not a luxury we can afford right now unfortunately,,

he tried using your original method of compensating for the displacement map by doing all the negative adjustments manually on a vertex manip level...

we're pretty much decided on cutting, subdividing, and manual editing for the features,,,,

I've been doing some nurbs again on maya just for the sake of practice etc.. they're working well,, but I've been using them mostly for terrain etc... there's a sweet tutorial in 3dworld this month on how to make flowing lava down nurbs terrain,, that kind of jumpstarted me back into the world of nurbs

 

[Shinobi]

UPDATE: FIXED IT



ok what you need to do, at least in 3dsmax, is set the RGB output parameter of the displacement map to -0.5

after you do this,, a displacement map will read like a bump map


thanks to zeddicus from the 3dbuzz.com forums for helping me out with this

 

[The Dark Elf]

Glad you got it fixed, Sorry I wasn't much help but my knowledge of 3DS MAX is limited at best. I did originally only get it for the basic stuff for work since some people insist on sending .max files, which is bloody annoying

 

[ankalar]

*touch wood*

I'm sorry but that was too funny.

 

[Shinobi]

Glad you got it fixed, Sorry I wasn't much help but my knowledge of 3DS MAX is limited at best. I did originally only get it for the basic stuff for work since some people insist on sending .max files, which is bloody annoying

thanks for helping out anyways, that gives me insight for displacement mapping in maya and xsi

 

[crabcakes66]

I'm sorry but that was too funny.

How is that funny?


have you never heard the saying "knock on wood"/"touch wood" before?

 

[ankalar]

I've heard "knock on wood" but not "touch wood." If someone told me to "touch wood" in real life I would probably respond with, "Here? In public?"