quick question on joint topology for a toad

umbrellabuddha

I am not sure which type of topology would be best for my toad's joints. In circle 1, I extruded the lower leg from the bottom of the upper leg and in circle 2, I just bent the leg around in the new direction.

Obviously, #1 looks much cleaner but I'm worried about how well it will straighten out when rigged... Any suggestions are hugely appreciated! thanks!:)

woogity

heya never done legs bent quite that much in their neutral pose but i think typically you would want to go with the way you have #2 otherwise when you animate it your knee will collapse in on itself i n the thigh when straightened, also since you seem to be in maya, painting weights will be a huge pain.

-Woog

richkid

i would straighten it out when modeling it. my animator would kick me in the nuts if i gave him something that bent.

Mark Dygert

Agreed with all of the above.

flow3d

yep, agreed
straighten it out a bit

but not fully straright, and not all this bent either .. somewhere in between eh? ;D


its nice to see somebody thinking about the rest of the pipeline, that is, rigging and animation
not just modelling a character in a cool pose and calling it a day.
nice to see some thought going into the other aspects of character creation

richkid

keep asking questions like this...and animators will LOVE you.

Frankie V

It’s hard to tell how the leg will deform with out seeing the direction of the hidden edges. In one there is a clear pivot between the upper leg and the second half. What looks to be missing is the accommodation for the pinch.

Think of how a fan opens up. Two points in space tied to a single pivot. As it starts to open it either stretches or unfolds the area between the two points.

In 1 I would want an edge cut from the outer knee to the pivot and two edges cut from the pivot into the pinch of the leg. That way when the joint opens up it open and close from the pivot much like a fan. Granted it breaks the quad but that’s what you will need to do on a low-density model.

You could always rig up a couple of bones, toss on a skin and rotate the joint to see what happens.

Rick Stirling

2 - but you can self intersect those polygons in that compressed pose in the same way that the elbow/knee intersects on a human character when bent.

Frankie V

Something else to take into consideration is how much volume does the joint need to displace if it is rotated. 1 displaces a lot more volume so would require more in the area of an accommodation than 2, as 2 would be much easier to rotate as it has very little volume.

In context with this example 2 will simply expand more than it will rotate to maintain both the volume and shape as required by an animator. 1 on the other hand is a more complex joint where volume and shape would be more difficult to maintain beyond the scope of the average skinning solution.

What is best is more of a matter of personal preference as some types of topology, joint wise, are easier to rig and skin up from an animation standpoint.

Most skinning solutions do not deal well with 3 dimensional translations and only behave in a 2d fashion with out additional rigging to account for the third. Granted bones could be add that stretch, or in the case of 3ds Max the use of angle deformers, to get the desired result but if a modeler designs all their joints based on a functional topology then it makes the job of rigging, skinning, and animation a lot easier as the design indicates it’s function.

The thing to keep in mind is the volume displacement and the limitations of just using a skinning solution to maintain as much of the volume and shape as possible.