Question about Displacement Maps

[xsi_fanatic]

Hi guys,

This is a generic question. I started diving into ZBrush and I'm not well experienced with displacement maps and I'm just trying to gather opinions of experienced artists.

Are displacement maps meant to give you a 100% replica of the real sculpt in the final render ? Or only a result that is close enough to the real sculpt ?

If the answer is no, then what can I do to make it as close as possible to the real thing ? What principles should I keep in mind ?

Just want to know what to expect.


Thanks for sharing,
XF

[Mathaeus]

Hi guys,
Are displacement maps meant to give you a 100% replica of the real sculpt in the final render ? Or only a result that is close enough to the real sculpt ?

Displacement map is meant to push surface along normal, that's all. It existed a long time before zBrush. What zBrush uses, it's probably kind of 'vector displacement', able to push surface in arbitrary direction, which then wants another map to define the direction. Tangent map or something else. By it's nature, it can produce tons of problems when it comes to rendering, especially rendering of animated deformations (which zBrush gently avoids, at all).
It comes after geometry, so it deforms color maps too. There's always question, what to with hair or fur, how to displace emission, in which way. What to do with overlaps, so easy to appear when displaced surface is so far from original. Finally, it's bitmap, so it's going through all process of sampling, blurring.

In short, I think your choice is a re-topology, for anything exaggerated. It's somehow sad story, to see all that options for improving the manual re-topology re-work, instead of some generic solution, but that's it.

[Pancho]

If you export the altered base mesh from zBrush together with its displacement map you should be able to achieve 99.8% the same visual result in Softimage. If you apply the displacement to your mesh in SI directly, than it won't be that precise. Alternative is to import the base mesh back into SI and use it as a morph target for your original mesh and them apply the displacement.

Keep in mind what Mathaeus said about hair. This will be sort of tricky.

Cheers

[xsi_fanatic]

If you export the altered base mesh from zBrush together with its displacement map you should be able to achieve 99.8% the same visual result in Softimage. If you apply the displacement to your mesh in SI directly, than it won't be that precise. Alternative is to import the base mesh back into SI and use it as a morph target for your original mesh and them apply the displacement.

Keep in mind what Mathaeus said about hair. This will be sort of tricky.

Cheers

Thank you both for your advise. 99.8% is really good compared to the results that MudBox achieves. It's easier than ZBrush but more frustrating to get the right details.

[Pancho]

It all depends on your displacement settings in SI. You need to choose "fine" in the geometry approximations and play with the settings. To get the same look might cause some additional rendertime. As long as you choose "displacement" and not "vector displacement" things are fairly easy.