Displacement Issue

[mad187]

Well ive spent the last few days reading forums and even asked about the work flow hoping to figure this out without asking so direct (feel like im lazy if i were to just ask without doing any research…but believe me…ive done lots and my projects hitting deadline so ive gotta hustle )

Ive got this trees UVs laid out using the maya pelt tool…isit Super impt for uvs to tally for zbrush?? i figured it would be fine cause when i put the checker onto the tree there werent any serious stretching whatsoever.

Anyway i cant get maya to capture all that detail ive drawn in…i did the whole base mesh exporting thing…tried morph targets as well.played with the balance values 2.2 and -1.1 and moved it up and down but keeping the later value half and negative of the first. im out of ideas.

whats causing all these problems?? ive highlighted in yellow the area where theres the issue and if u look at the detail… ive lost everything
ive used 2048 texture and dpsubpix 2
and even tried 8192 with dpsubpix 2 - didnt take very long surprisingly.15 min but anyway even at that resolution im not getting all those information…my .map file is 1.2GB hahaha i cant solve this…anyone could give me a hand?? thanks so much guys

[aurick]

It looks like your UV’s compress a lot of trunk length into a very small UV space. The portion running from the roots to the first branch is quite short on the UV map, but pretty long on the actual model. This would then force a transition between the two parts of the model.

Basically, it comes down to a point-to-pixel ratio variation. For the trunk up to where the first branch is, your model has one ratio for how the tree’s points correspond with the map’s pixels. Then the rest of the tree has a different ratio. This means that in order to create the displacement map, ZBrush would have had to try and reconcile those differences. In this case, a lot of detail would be discarded from the trunk because there just aren’t enough pixels in that part of the map.

One or the other part of the model could be adjusted to render so it looks right (although the lower parts of the tree would never have the level of detail that the rest does). But the other part won’t be quite right and there will always be a transition point visible in the render.

For best results, your model needs to be unwrapped without any compression of the UV’s taking place at any point. A certain number of points in the model should always correspond to the same number of pixels in the texture, regardless of the part of the model those points come from.

[mad187]

Ahhh i see. okay thanks so much aurick!

would you guys then suggest i use maya and run the unfold uvs over the whole trunk? or use zbrush to layout the uvs for me? if i did ask zbrush to layout the uvs using guv - would i get the kind of quality i am looking at in zbrush?

how would you guys do this?

[aurick]

I would definitely remap the model one way or another.

GUVTiles allows you to get a distortion-free map instantly, and will render just fine in other apps. Simply apply a blank texture to the model that’s the same size as the map you’re going to export, then press GUVTiles. You’re now ready to create your displacement map and/or textures.

Just be sure not to use any kind of texture filtering in your rendering engine. Texture antialiasing and MIP-mapping, for example, have a way of pulling details from outside the UV edges and making seams appear in the render.