This document discusses the basic techniques for applying and using UVW mapping on models
such that they can be easily animated and rigged so that the texture mapping "sticks" to
the model. The basic technique decribed works for both low poly/meshsmoothed objects, and
surface tools modeled surface objects. The descritpions/stacks show the polygon based
modifiers, but also have the proper spline/surface modifiers in paranthesis next to the corresponding poly modifiers when appropriate.
The Basic Stacks - CASE 1 & 2
There are two main approaches to mapping a model so that the texture sticks. Case 1 is
mapping the model at the unsmoothed/low res version, the other Case 2, is to apply
the mapping onto the high detailed/smoothed model.
The basic stacks for each case would look something like this:
CASE 1: CASE 2:
Meshsmooth(Surface) Skin Skin Morpher Morpher UVW Map UVW Map Meshsmooth(Surface) Editable Poly(Spline) Editable Poly(Spline)
In case 1, you take your base object, either Editable Poly/Mesh or the Editable Spline and apply the UVW mapping immediately on top, followed by the deformation modifiers and then smoothing. This is my favorite, because it allows you to apply mapping on a very simple object. It also allows you to skin and weight many less vertices, as well as generate morph targets from a nice low poly/simple spline object. You can also set the viewport tesselation for smoothing to be lower than rendering, so you can get faster interactivity while animating.
The disadvantages include the fact that mapping is indeed on the low poly/spline cage. This means when it IS smoothed out, mapping may be adjusted a bit and may not flow exactly as you expected. Basically when you are mapping it, you will want to switch back and forth between Photoshop and the final version to make sure things look right. But generally if you just use something like Mankua's TLUnwrap or Peter Watje's Unwrap Utility, then you can paint right on the low poly image and you will get what you expect. If you are using a 3D paint package, you can export the low poly model, UVW map it, then apply the skinning and smooth as in Case 1. The result again is nice because you can then paint either on the low poly model, or even better, bring back the newly smoothed version into 3D paint like Deep Paint, and then paint away on the hires model. Because the UVW's basically correspond to both that will work fine.
Case 2 is a little different, in that rather than smoothing at the very end, you smooth right away. This means you get to paint and map UVW's on the hires/smoothed version. You'll be able to map it exactly how you want, with no distortion. The issue with that is you will have a LOT of polygons or detail to map. You'll also have that many polygons to worry about when skinning and setting up your character to deform. You won't be able to disable or lower the smoothing interactively, because then skin will get confused since it suddenly has less points weighted.
Case 2 is my least favorite method because I hate skinning and making hires morph targets. You could make morpher targets based on the low poly version, by adjusting the base mesh for each target, and then assuming you will get the same point count and order...but that can be tricky sometimes. I'd much rather have skinning and all at the simpler stage.
As an important note, you see that morpher is always BELOW Skin in the stack. This is also critical, because you want the morphing to occur and then skin/bones to move the mesh. If you had it the opposite way, what would happen would be skin would move the vertices, but then morpher would cause the points to go back to the morph target, as if skinning had never occurred. Also you can feel free to replace the "Skin" modifier with "Physique" if you are using Character Studio.
It is also important to note that the deformation modifiers, like Skin and Morpher are ABOVE the UVW mapping. The reason for this is that the UVW mapping is basically projected onto the mesh as it looks at that time in the stack. If the UVW map was above the deformations, it would project the mapping onto the newly changed model, as if it was just a different model, the result being that the texture is locked, but the model appears to "swim" or move through the texturing.
But wait folks, that's not all! - CASE 3
Of course there is one other important way you can map with MAX. This involves a little
trick using the UVW Unwrap -modifier-. This modifier normally allows you to adjust the
UVW points relative to the map after UV's are applied. Allowing you to effectively hand
tweak how the mapping lies on the model, without actually changing the model itself.
This same modifier however, also has the side effect of locking or pinning the map in place, even if normally the mesh below is moving and would cause the texture to swim through the model. Because it locks the model, it means you CAN map the model above the deformation modifiers, and then lock it via this modifier on top, so that things stick.
The corresponding stack is this :
UVW Unwrap UVW Map Meshsmooth(Surface) Skin Morpher Editable Poly(Spline)
This is another goody, because it does allow you to skin and morph the lower detail version of the model, but also gives you the control of mapping and painting the hires version of the model. The only catch is you'll probably want to make sure that the smooth value doesn't change once things are mapped. For example if meshsmooth is set to iterations of 2, and you map it, then funky things may happen if you try changing it to 1 or 3 for example. That being said, this another popular method for many people.
That's about it for how to do mapping. As mentioned it is nice to be able to take your UVW
mapped model, and extract an image that has the wireframe of the model flattened out so that
you can paint right on the image in photoshop.
There are 2 basic plugins for this, one is TLUNwrap by Mankua. This thing has a number of options and works pretty well. It's a modifier you can apply and then remove after using it. Right now it is under their "Clay Tools" which are their free downloadble plugins.
My personal favorite and another freebie is the Unwrap Utility which can be found at Peter Watje's page. The Unwrap Util for MAX will show up in the utilities panel, and lets you unwrap specific material ID's, or tick points, and set the desired map size for outputing. Check it out, it's cool. Note: Make sure you are grabbing the Unwrap Util and NOT the UVW Unwrap Modifier.
Thanks to all the cool guys at Discreet who work hard to make MAX a great package!
About the Author
Michael Comet is currently a Rigger/T.D. at Blue Sky Studios in New York.
Previously he was Lead Rigger and Cg-Supervisor of the Video Team and a
3D Animator/Artist at
Big Idea in
Lombard, IL where he is worked on "3-2-1 Penguins!" and "Veggie Tales".
Prior to that he was lead animator at the video game company
Volition, Inc., where he animated many of the cinematic
sequences for Descent: Freespace, and headed up much of the realtime character animation and
cinematics R&D for their RPG title, "Summoner". He can be reached via email
at email@example.com, and has a
personal homepage at: http://www.comet-cartoons.com/
which has more information and samples of his work
About the Sample Images
This article, all images and text are Copyright ©2001 Michael B. Comet
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