Hi-Poly Unwrapping...

SyaPed

Does anyone know of any tutorials/guides to hi-poly unwrapping?

Do you guys unwrap the lo-poly cage and then apply sub-d, meshsmooth or whatever afterwards? When I try this the uv's get warped from the smoothing, especially around the seams. It gets really bad with a technical/mechanical model, as there are alot more seams and chamfered edges that get messed up... So maybe I should unwrap the hi-poly?...which sounds like it'd be a bitch :P I'd love to hear how you guys go about it.

I'm using max.

Thanks!

JordanW

I think if you apply UV's to a low poly then meshsmoothing, you're likely going to have weirdness show up. You might want to give max7's new tranfer surface info tools a try. I know you can make a low poly cage around a highpoly one, UV the low cage and transfer the UVs, this might be what you're looking for.

KMan

I'm quite positive that using a meshsmooth on an already unwrapped low poly cage works fine. It will smooth out some of the sharp shapes on the unwrap, but that is easy to tweak.

Daz

Not Max I'm afraid SyaPed, but I have some notes on the subject here:

http://home.comcast.net/~dpattenden/hi_poly_tut_uv.htm

Workflow should be unwrap control cage>smooth yes, and certainly not vice versa no.

SyaPed

Thanks for the link Daz , that tutorial should help me with the entire process of the model I'm working on...

I'm mainly having a problem with uv'ing hard edged, technical things. Here's some pics to help me explain...







The same thing happens if I try and uv map the chamfered edge along with the outer side of the cylinder...I hope that made sense...

Would you guys just ignore this? Or manually clean it up afterwards? Or maybe something I haven't thought of yet...

Marine

i'd try playing with your smooth options, maya has an option called "keep map borders" with the choices none, internal, all. all produces a similar kind of edge distortion that you're seeing there. max probably has a similar option with in it's smooth.

Noren

It's not you uv's that bleed over the edge, it's your geometry. Try to fix that and your problem should be solved.

FatAssasin

I know what you're talking about, but I usually work on characters so it's not that big of an issue. But here's something to try, instead of chamfering the edge, use extrude. Select the edge loop, click the extrude dialog box button, and set the Extrude Height to zero, and then adjust the Extrusion Base Width. This acts as a chamfer while keeping the original edge loop intact.

You might even want to UV the model, without extruding the edges, apply the Meshsmooth modifier, and then go back to the botton of the stack and use the extrude method with the Show End Result toggle button pressed so that you can see how sharp or rounded your edge will be as you're adjusting the Extrusion Base Width amount. Hope that makes sense.

I just did a test and this method does seem to keep the UV edges correct when you add the Meshsmooth on top. Give it a shot and let me know if it works for you.

SyaPed

Hey thanks FatAssasin! That method seems to work pretty well. Though now I have to go back over the model and change all the chamfers

Sorry if I'm becoming a pain but there's one more thing I'd like to know if there's a fix too...



In the picture I have a low poly cylinder that was uvmapped then meshsmoothed. If you look at the UV's after that you can see that they've been smoothed too, except for the border of cylinder end. Which keeps the shape of the low poly cage. Which creates some UV stretching. I did make this example more extreme then it'd be on a real model. Is there a way to correct this? Or am I being waaay to picky?

Noren

In a simple case like that, I just would remap the cap of the cylinder but here are some solutions for more complex cases:

If you don't care about the extra polies:
Just extrude those "seam-edges" by 0/0 like FatAssasin said. The distortion will be hidden away in this newly created tiny rim.

If you have Deep-UV or any other Program that can relax uv's in relation to the 3d-geometry:
Just hit the relax button and in most cases things should be fine. This would be the preferred method if there are many of such areas in your model.

If you have the time:
Select those seam edges in the geometry and split them. Then do your Subdivision and merge those edges back together. The uv's should smooth fine. (Take note however that e.g. the rim of that round lid in your example should have a row of quads running around it in order to smooth properly after detaching. )
This problem seems to occur because the uv-vertices of the seams seem to be held in place by the other uv-vertices they share the geometry-vertices with. Though this can be convenient from time to time there surely should be a checkbox by which this behaviour could be triggered.
On the other hand one could perhaps write a script for that.
(Perhaps there even is already one.) And perhaps there is an even simpler solution for that problem, that I'm not aware of .

Toomas

There is this option that lets the UV patch (or whatever) edges be smoothed aswell (''keep something'' you have to uncheck). I dont have max handy so i cant say where exactly it is (should be somewhere in the Edit UVW's window).

Delaney King

Dont forget to check out crease edge too mate.