Preserve UVs not preserving anything in Max

Chase

In the viewport everything looks fine, but when I apply an unwrap modifier the UVs get distorted, verts and edges get twisted around. I'm using Max 2012.

Notes

I wont preserve everything perfectly, I usually get problems when I try to move verts/edges that are on the borders of the UV islands.

Chase

Well that sucks. What's the point if youre just gonna have to redo the unwrap

Noors

That shouldn't be.
Also i think you didn't get what preserve uv do. It allows you to move your vertex, faces, edges in the viewport while keeping your uv kinda intact. It barely 100%works if your uv's has some distortions. It works great for something with a planar projection for instance.

When you apply an Unwrap, the uv's shouldnt change. Are you sure you're on the good channel (Map Channel 1 ?) Hard to help without seeing the scene or a screenshot.

yiannisk

preserve UV will attempt to keep everything perfectly. and most of the times it does.
however it is not going to rearrange your texture.

what preserve UV does is slide the vertex on the existing texture page's UV space, now if that vertex you pull is on the edge, and considering that a texture page often is tightly packed, then it will, of course, reach some other nearby part of your texture page which is irrelevant with this part of your model.

As Noors said, there is no reason why your UV would get messed up unless some bug is there.

cptSwing

Try an Xform on your mesh before unwrapping?

AlexCatMasterSupreme

Don't use preserve uvs on a unique texture either. Something tiled should work somewhat well depending on what it is, such as making a wall longer.

AtticusMars

Why would you not use it on unique textures? I use it on unique unwraps all the time without issues. It's very useful for cutting folds into clothing of hand painted characters.

Chase

Here's what's going on when I pulled out the faces from the back wall of my model and scaled them out. I didn't extrude, I just used the move tool.


You can see the faces that get extremely distorted.

Here's what happens when I extrude and scale that same selection


One of my other models is reacting fine to that same process, but others like this are giving me UV nightmares.

yiannisk

ouch! that is a UV bug! (or bugged geometry) i assume you have installed all updates?
reset xform your model and try it again. if it doesn't work, your object is bugged.
try exporting to 3ds and import back.

Noors

Doesn't really shock me. Do you have preserve uv on or off ?
If it's on, if you move/scale/rotate a geometry face/edge/vertex, the uv will move too. On your screen, only your selected face is screwed up.

Check the help files but again, preserve uvs is only used in specific situations (scaling a plane and keep the correct texel ratio for instance) and generally speaking, it has to be off.

Also yeah, reset xform your object. The transformation on your objects (scale/rotation) affects all uvs projection, preserve uv, etc...

If you create new geometry, it is more likely that you'll have to unwrap it. Max doesn't create good uv's on creation like UDK bsp for instance.

pior

I think it might be a bug here. IIRC last time I tried to use it (in Max 2013) it wasn't behaving like it should have (2009). I had to use the tool "blind" (with weird distortion and artefacts )and then apply an editmesh modifier on top of the object stack in order to display the mesh without errors.

To the OP : is that the behavior you are getting ?

Ace-Angel

Confirm on my behalf, even with the latest update, the UV Editor will ignore your Preserve function sometimes, and sometimes it will only show the symptoms AFTER you have collapse the UV layer on the mesh.

*insert edgy autodesk complaint in here*

Chase

I needed to just reset XForms. Seems that I always forget that and it's such a simple issue. Thanks for the suggestions anyways guys! I'll keep all this in mind the next time something like this happens.