Seamless Skin Advice
08-Sep-94 15:31:34
Sb: #122801-Seamless Skin Advice
Fm: M. G. BATCHELOR 71532,1214
To: John Mateer [PolyMedia] 100116,343
Hi John,
Thanks for the kind words.
<< I am trying to model a reasonably detailed, seamless skinned hand with fully
articulated fingers. I've tried your common cross-section approach (or what I
gather is your approach from playing with the branch examples) but I can't get
a clean 5 fingered model. >>
Hmmm. Hands are very difficult in general, specifically with this approach, &
consequently because you're implying close-up shots of the hands – thus it's
more difficult to achieve the "misdirection". In fact, the hands for the woman
model are not "seamless".
<< I've tried using more complex control objects but I seem to lose control of
the contours and the model looks too angular. Do have any tips that could
help? >>
When you say "more complex control objects", I assume you mean either more
vertices per CS, more CS's, or both. With Skinned objects, the key is in using
LESS resolution & less CS's if at all possible. If you skin a simple cylinder
with CS's composed of say 16 vertices, it's going to appear more angular than
from CS's using just 4 vertices – especially when you raise the
resolution/smoothing bias. If you must use higher-res CS's, then you really
need to crank the smoothness resolution up, and raise the bias in the direction
where you need the smoothness.
In general, the seamless branching technique is very similar to lofting with
back-tracking paths. Except with individual CS's & Skin, you're doing it in the
Editor. To create a hand & fingers, you'd have to start from the wrist with
CS's for the hand, then step your CS's down to finger size, create the length
of a finger, step the CS's down to close off the fingertip, run yourself a path
of CS's INSIDE the skinned finger's surface, come back to finger size inside
the hand's skinned surface to start another finger, etc.. You also may need to
double or triple CS's at various points along the way to shape the skinned
objects. As you can see, with a hand, 4 fingers & a thumb – this just may not
be practical or even possible, and still obtain good rendering – especially
with a close-up shots.
The only other possible approach is to use a spherical template with enough
resolution in this case, to literally "pull" your jointed fingers out like
taffy. But of course with this method, articulating the hand becomes much more
difficult as the hand is not constructed from CS's which can be linked to dummy
skeletonal objects for animation purposes….not to mention the very abstract
nature of modeling this way. You would have to make numerous morph targets
utilizing extensive vertex-level manipulations – but the hand would be seamless
<g>.
Wish I could offer more, but that's the long & short of it.
Regards,
BILL