Hi Reinhold,

I’ll try to help you a step further, as this is an interesting and far from trivial situation. This might turn this thread into a mini tutorial, but who cares. The main questions to solve are:

• is the situation feasible in reality
• is 3D able to follow reality close enough
• if not, what else?

Reality check

This slender person without heavy leg muscles might be able to bend the legs up to 120*, but be aware that lower and upper leg skin will start touching behind the knee from 90* on. Bending the leg with elongate the path over the knee, hip to toe, with about a hand length (say 15-20 cm), and will shorten the path at the back, from buttocks to heel, with about the same amount. As a result, the pants will raise at the ankles, and an awful lot of cloth has to be wrinkled away behind the knees. Looking at my own pants, four serious folds seems to be the minimum to get the job done, and folding starts halfway my upper leg already.

If the jeans are tight or thick the pants will have problems making all the folds and wrinkles, and will actually hamper the move and pose. The cloth will get crushed behind the knee, and things become uncomfortable in due time. 

When looking at your image, I only see one sharp fold behind the knee, and that’s it. It seems like high fold- and stretch resistance to me, thick lumberjack jeans or even leather like. The pants seem tight around the upper leg too, so the pants get sucked into the tight area behind the knee instead of being able to avoid it.

So my first tests would be to widen the hose a bit, relax the cloth parameters and actually animate the bending of the leg while sitting, to enable the simulation to get the cloth and folds in place. Just a few frames will do, and you might increase the number of steps per frame to 5 or 10 (instead of the default 2). This will increase simulation time a bit, of course.

3D ability check

As pointed out in posts above, Poser does support hard bodies only, and everything soft has to be emulated using morphs and other distortions. Cloth simulation is not different, it’s just a way to derive those distortions but the cloth remains a hard body too. Objects passing through each other can be prevented by switching on collision detection, but that’s about it.

First, cloth simulation offers a basic collision detection plus three extra features. Use them all, they only give real longer calculation times in case they matter. Which is in cramped conditions like this, and when making wild moves or extreme poses while the cloth has a relative low poly density. The simulation offset give the cloth its thickness, that is: when set to say 1 mm it will remain this distance between cloth and skin and between cloth and itself. Anything within this distance will be considered a collision.

In your case, a decent flow of cloth behind the knee requires 3 mm: 1 for the upper leg, 1 for the lower leg and 1 for the cloth bending and folding onto itself. The issue in your case is: when the pants are so tight that the cloth is sucked into the tight area between upper and lower leg, this room may not be available. So reducing the simulation offset might help in cramped situations.

Second, is the cloth 3D mesh able to make the folds and wrinkles? If you are relatively low in polys in that area, two neighboring ones are folded about on top of each other like making a sharp fold in a sheet of paper. And since smoothing of a mesh stops just before 90* bends, those folds will come out quite sharp. The solution, as pointed out in posts above, is to crank up the poly density at least a tenfold (order of magnitude). Just doubling won’t do I guess.

What else?

Poser was designed for artists to get the main things right, and work from that to a sculpt, a real (analogue) painting or a digital illustration. Most people work like that, and make the final image in post improving on everything a tool like Poser can’t offer. Wrinkles, lighting details, color dynamics, camera features like depth of field, and so on. 

So, when the objects and tools fall short (and they will, even in version 900), nothing stops you from painting the folds by hand. Or to trade a few hundred bucks Poser for a few thousands bucks feature film tool like Maya or so. Well, your wallet may.

Hope this helps.

Ronald

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Usually I'm wrong. But to be effective and efficient, I don't need to be correct or accurate.

visit www.aRtBeeWeb.nl (works) or Missing Manuals (tutorials & reviews) - both need an update though