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View Full Version : Character rigging + weight map questions - pics inside



Arcturus
12-29-2004, 10:35 PM
I just completed a model of this robot:

http://www.markschumann.com/robot/robot.jpg

This is the first time I've tried to rig a character. Basically I want all metalic surfaces to not distort at all while the accordian-style areas distort when sections are moved. I placed bones within the legs for a start, with smaller bones within the "bendable" sections. I gave the metallic areas a weight of 100%. When I bend one of the knees I get heavy distortion to the other leg and surrounding surfaces:

http://www.markschumann.com/robot/legs.jpg

I'm sure there is a simple solution, but bear in mind I'm a total newbie at rigging / weight maps, etc. Any suggestions would be greatly appreciated. I would be happy to supply the object/scene files if someone could show me a good way to rig this character, in fact that would be even better :)

Arcturus
12-29-2004, 11:02 PM
I think I figured it out :) I had used a single weight map for all metallic surfaces. I should have renamed each one with a weight of 100%. I have another question though, what would be the best setup to bend the knee realistically. At the moment it seems to bend without distorting the metallic parts, but the bendable area doesn't seem to distort correctly. Here's a pic to show you what I mean, I have a small bone in there, should I put it another way?

http://www.markschumann.com/robot/knees.jpg

Mipmap
12-29-2004, 11:25 PM
To bend the knee you might try a weight map on the middle part of that rubber stuff that is 100% in the center and falls off to 0 at the edges so it will keep its shape like its attached to the nonmoving metal and will bend and stretch in the middle.

Arcturus
12-29-2004, 11:38 PM
To bend the knee you might try a weight map on the middle part of that rubber stuff that is 100% in the center and falls off to 0 at the edges so it will keep its shape like its attached to the nonmoving metal and will bend and stretch in the middle.

Great idea, thanks. Once again I figured it out myself to a degree, though your suggestion is much better. What I did was use 100% weight on the top and bottom of the rubber areas so they wouldn't come off the metallic areas, and insert a couple more bones in the middle. I think your suggestion will produce more realistic results though.

Arcturus
12-30-2004, 01:30 AM
I have another question. Is it possible to resize or stretch a single bone without it affecting the others? For example I might want to stretch just the rubber area, but it affects the whole arm as well... i'm sure there's an option somewhere but I can't find it.

faulknermano
12-30-2004, 04:53 AM
I have another question. Is it possible to resize or stretch a single bone without it affecting the others? For example I might want to stretch just the rubber area, but it affects the whole arm as well... i'm sure there's an option somewhere but I can't find it.

i think this is called "inverse scale" in maya, often for the purposes of rigging. anyway, you *may* be able to achieve it using expressions. something like:

thisBone.Scale.Z = 2 - thatBone.ScaleZ;


not sure really. but the idea is the scale down the other bone while the other one scales up.

theo
12-30-2004, 07:02 AM
I wonder if to help disguise the black rubber areas separating from the green if it should not have been modelled with the entire structure in one piece rather than separated as you have it now as it appears.

MGuerra
12-30-2004, 08:24 AM
I don't have any advice about your rigging questions, but I think your robot character is great! I love the rubber accordian look around all the joints.

Arcturus
12-30-2004, 03:36 PM
Thanks for the kind words McGuerra.

Theo, that's a good point... i guess I initially modeled with "robot" in mind so I did it in parts, I might try some welding as see how it turns out.