It seems to me that the dynamic clothing simulation model in Poser is not particularity sophisticated. Dynamic clothes work reasonably well when a character is posing gently (like in walking poses). But if you want to try more extreme poses, like sitting or running or anything that requires your character to twist his body or bend his limps more than about 30 degrees, you are heading for trouble. Fabric crumbles and breaks down particularly in the joint areas. At least this happens if you are trying to simulate pants. No doubt sleeveless dresses and skirts are a bit easier clothes to work with.

I am not a mathematician or simulation expert but surely better simulation algorithms are possible. What do you think? Is this going to happen in the near future for Poser?

Does anyone have experience about DazStudio dynamic clothing? Studio doesn't have enough actual cloth items to make the feature usable, but does the simulation algorithm work better than in Poser?

Reinhold Pupu

I'm curious about that too. I personally love dynamic clothing, and pretty much everything I model is dynamic..  I've seen a thread here earlier about a potential third party plugin that looked very promising, too.  Maybe such things could make it into future versions of poser, just like Wardrobe Wizard did?

I think that the future of this technology sits firmly in the laps of those that use it regularly and comfortably. I'm not one of those, yet, but like with the material room, I can see the advantage to getting one's head around it.
Put a figure in conforming cloth in an extreme pose, and you'll be using magnets and post-work to deal with pokethrough. I've seen samples of some dynamic cloth - KobaltKween's V4 Catsuit being an incredibly vibrant example - that deform quite well even with the figure in extreme positions.

Be sure to have a look. I need to have a few days to have a play!

In my opinion, the Poser dynamic clothing is very very good, and I do know my way around animation, cloth and fluid dynamics and the like. The dynamics follow physics laws quite well.

A few remarks though.

1. the simulation settings offer some checkmarks to elaborate on the default vertex-to-poly collission detection. The definition of the dynamics also offer options to stick parts of dresses etc to the body. One does need and understand those things, especially for handling extreme cases like tight or thick clothing, or wild moves in animation. I did a thread on this some time ago.

2. the cloth might need some parameter adjustments, to define its structure, internal frictions and resistances and response to forces. The simulations assume a clean atmosphere of medium density, medium humidity and so on, wind forces can be added and perform according to physics laws. Gravity is according to average Earth surface conditions. Other conditions, like rain, water absorbtion, underwater cloth movements, exceeding the sound barrier and dancing on the moon or Jupiter are not supported, but can be emulated by changing or animating the cloth defining parameters.

3. figures movements should stick within limits or even more restricted to avoid unnatural positioning of limbs and body elements. Age, condition, obeseness and clothing itself ! are known limiting factors. One cannot make sharp leg bends or perform Swans Lake in a tight hose of thick leather. You also cannot break world records at 100 mtr sprint wearing a royal robe or evening gown. This means that when simulations go wild even after setting the right parameters, you're usually trying to make a move or take a pose which is highly questionable in real life.

In my personal opinion, all these are valuable assets, and I am quite happy with a feature which prevents me from treating carpet for lace or so, and questions my animations given clothing. But dynamics in all its facets it quite a complex area, so I promiss to make a thorough advanced level tutorial on this (before the end of this year). So, when all it set properly and simulation still cannot follow your poses, you might resonsider the poses instead of the dynamics. Again, in my opinion.

My only annoyance is that the gravity in Cloth dynamics differs from the gravity Python script somewhere in the menu. So when you have a ball and drop it by the gravity script, and you have a very dense piece of cloth with ZERO air resistance, and drop it by cloth simulation from the same position, they are not falling equally fast as they should do. One of the algoritms is correct for 30 fps but well off for 25, the other takes a middle position and is slightly off for both. As a result, dropping a table with tablecloth result in physically incorrect results.

I already filed this in the thread on Poser 9 fetures.

I'm open to all questions and suggestions, to deal with in the tutorial.

Regards.

If you are getting Clothing tearing apart (Mesh breaking) that is an issue with the Cloth Prop. You can twist, bend, etc... without issue.

I suspect if you had some real odd Cloth Settings, you might ba able to create severe kinks in the cloth.

If you have an example of this issue, contact Support (or post it here). I am betting that if it is not the cloth Prop, it is severe Cloth Settings.

With regards to enhancements, contact Support with changes or additions you would like to see.

When I referred to extreme poses in the first message of this thread I didn't really mean anything too "extreme". Just sitting or running or kneeling for example. I have fiddled around with different simulation and cloth settings and they make a huge difference, but they don't eliminate the basic problem. Fabric has a tendency to crumble in certain areas. This simple picture will illustrate what I mean.

Now I am sure that there are tips and tricks which will help. One is to animate a sphere inside a joint in an attempt to stop the fabric from getting stuck between body parts. But it is difficult and will not, I think, guarantee better results.

Problems with dynamic bothers me because personally I don't like to use conforming clothing. Basics of the cloth room are simple enough and the basic simulation principle seems sound.

Reinhold Pupu

Agreed that those are not "extreme" bends. But - if we expect a cloth sim to correctly calculate small and tight folds (not simple wrinkles) then you need more and smaller polygons. When a few polygons are asked to bend and twist to that degree, the corners stick out. If you were to re-model the cloth or subdivide it, you can get better looking folds.

The issue where cloth gets pinched and squirts through body parts is tricky. I don't have great experience in that area, but I've come across situations where it matters what sorts of collisions detections you enable. Of course, turning on more sophisticated collision checking results in much longer computation times. I don't have personal expertise in that area (3D geometry math scares me, believe it or not) so my opinion ain't worth squat, but I suspect some improvement in that is possible.

I think the real problem is the body parts themselves are not colliding, but actually passing through each other. The sim needs to take into account meshes "pressing" against each other, even when they are not cloth, and leave a little space between. That would be a superb addition to Poser - real soft-body dynamics. All sorts of realism problems in posing would go away if we had that. Like - human butts do not pass through a chair seat, but they seem to be doing it every day in the Poser gallery. giggle

Thank you, Bill. That has been my first request since the P5 questionaire; softbody dynamics would be a godsend to animators. It would also probably scare the jujubes out of the casual user, just as dynamic cloth and hair still do (but progress -is- being made....albiet very slowly). I suspect that it would remain a Pro only feature, as it would take some development, and consequently make Poser a bit more expensive. Just how it would function is open to debate (maybe an inner set of solid bodies to provide the internal support needed. Or maybe just predefined soft zones at joints and particularly fleshy bodyparts). Probably would need some form of subdivision as well.....

I solved many of those issues like with the pants by subdividing the object, to create extra polygons. I have a hires version of my own models ready all the time, and I subdivide other dynamic clothes I've bought/freestuff whenever needed before running a final simulation. There are some pretty decent python scripts to do that right within poser. :)  Since dynamic clothing is a single object file, this is usually a pretty simple procedure.

I usually have a lower res version when I am working on the project itself, since the calculation is faster. Then when I'm ready, I'll switch to a higher res version for the final calculation.

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

Quote - I think the real problem is the body parts themselves are not colliding, but actually passing through each other.

Exactly. To answer your original question, the future of dynamic clothing may be unconnected with the cloth itself, but to extend simulation technology to the figures. It's all very well having an accurate cloth simulation (and we all know situations where it isn't very accurate - yet), but when this cloth is interacting with flesh which is apparently made from solid plastic, part of the equation is missing.

to bagginsbill and englishbob,

you know, I'm just not sure. Because when upper and lower leg intersect at the kneebend, there won't be any room left for the cloth inbetween, and the simulation would make the cloth flow around it like in real life, unless the pants are so tight that a clash cannot be prevented. Relaxing the leg such that the intersection goes away would not make the pants cloth flow correctly. This is why I wonder whether any intersection can be an underlying cause.

So I'm curious to your considerations, why you think it's so relevant.

And I haven't seen the model without the pants (yet, perhaps Reinhold can show us), so I can't tell. I guess I'll have to fire up my Cloth Testing Lab :-) for this weekend, then, to find out.

To be continued...

Quote - I solved many of those issues like with the pants by subdividing the object, to create extra polygons. I have a hires version of my own models ready all the time, and I subdivide other dynamic clothes I've bought/freestuff whenever needed before running a final simulation. There are some pretty decent python scripts to do that right within poser. :)  Since dynamic clothing is a single object file, this is usually a pretty simple procedure.

I usually have a lower res version when I am working on the project itself, since the calculation is faster. Then when I'm ready, I'll switch to a higher res version for the final calculation.

Which scripts are these?

Quote - So I'm curious to your considerations, why you think it's so relevant.

Speaking for myself, I was only speculating about Reinhold's original question:

Quote - I am not a mathematician or simulation expert but surely better simulation algorithms are possible. What do you think? Is this going to happen in the near future for Poser?

I wasn't trying to tackle the specifics of the problem shown in the image he posted later since you seemed to have that well in hand anyway. Apologies for any confusion I may have caused.

Quote - Which scripts are these?

Cage posted a subdivision script in this thread which seems to work reasonably well.

Which scripts are these?

PhilC has a pretty good subdivide script in his Poser Toolbox.  

I loooove Poser cloth room. I never have any problems with it. Some say it doesn't have as many bells and whistles as top high-end apps but, as of now, it serves my purposes and never gives me a headache. It just gives me beautifully draped clothes EVERY TIME.

first you need to realize that 90% of poser users use conforming clothing. that automatic means that there is no reason to spend extra money to make dynamic clothing better.sorry but it is how it is.

i can accept slow poser dynamic calculations.  and i dont need it faster.

but there is something where i am insulted that in 2010 they didnt fix it. its this paper.

http://graphics.pixar.com/library/UntanglingCloth/paper.pdf

the reality is that in CGI in 3D software body parts are going through different body parts. you can not expect that everything will be physical correct. crazy.

so you need to build a dynamic engine that will understand that when the arm goes a little inside the leg ,that teh cloth can not explode and crash. but it does. IT DOES. in poser when an arm goes inside the leg just a little it doesnt work.

so first before doing aything fancy you need to do the obvious. and this is this paper.

http://graphics.pixar.com/library/UntanglingCloth/paper.pdf

ohhhh and dynamic clothing rocks. it takes 1 month to learn the basics.

Treu enough.....but those of us who are slightly less than casual users also know that conforming clothing is essentially adding an extra character....with the polygon and texture overhead that entails.

Now the ideal solution would be to do it right....as in leave the nude figure nude, and for clothed, only be able to attach the body parts that would be revealed, and have the 'figure' beneath the cloth as low res as feasible, with contoured joint structures that, within the limits of motion, =can't= break the sim. But I doubt that kind of multiple figure construction would be financially viable in the Poser world. Softbody dynamics would suffer from the same simulation time issues that any other dynamic feature does, but as is true in most things, time spent well is well spent...

This picture again shows the problem There are 24000 faces in the pants (4 x more than in my last picture). Simulation settings are

3 fold resistance

50 shear resistance

30 stretch resistance

0,01 stretch damping

0,005 cloth density

0 cloth self friction

0,5 static friction

0,1 dynamic friction

0,2 air damping

Collision offset and collision depth 0,2, four steps per frame, 40 frames simulation. Last 10 frames are for final draping. All additional cloth collision options checked.

Is this a problem of cloth intersecting with itself and making a mess of it? I tried subdividing pants once again but simulation time became too long, and besides, even that did not solve the problem.

Maybe Posers dynamic cloth algorithms try to be too perfect. Too accurate and, at the same time, too dumb. I think that for dynamic clothes simulation to really work you will have to program in exceptions and limits that will handle the difficult situations without losing general impression of realism. That is why I was asking your experiences about DazStudio dynamic clothing. Is it easier there to make a pants wearing woman sit?

Reinhold Pupu

Since the pants fit fairly snug, what would happen if you constrained everything from the waist down into the upper leg? I would imagine you would lose the wrinkles though.

In P8 or 2010 in a still, I would probably try a few smoothing passes with the morph tool, taking care to stay away from the clothing edges at the waist. That more than likely wouldn't work well for animation though.

Did you enable cloth self-collision? Looks to me like the folds are passing through each other.

While 24K polys seems like a lot, it isn't. How many are involved in a cross section of one of those folds? 3 to 5 is not enough.

 this pose is in the CGI world a very extreme pose. everyone is afraid of it. and for this you need a good software for cloth.

they just need to fix the body self collision and IMO everything would be 50% better.

This is a pair of V4 conforming pants converted to dynamic, 2.4k faces, 2.6k verts. I exported a welded object using PML, imported and parented to the hip of a zeroed V4.

I ran it through the cloth room (30 frames) with frame 1 zeroed and frame 30 posed. By constraining all verts from the hip to just below the knee and using the default settings this was the result with smoothing turned on.

hi bevans84,

see where you're coming from. Point is that constraining pants from hip to below the knee doesn't leave much dynamic, and as you said yourself, doesn't give much wrinkles and folds either. Therefore, it doesn't look like jeans pants to me, while constraining the belt should be enough.

I'm afraid this doesn't help Reinhold, as "take a helicopter" is not the answer one is looking for on the question "faster path by car". It's faster indeed, true, but the car got lost in the process.

Your notes are well appreciated though. Let's go for the folds. This is an interesting thread, isn't it.

Well, I spent about 15 minutes on all of that. Were I having problems with something I was doing, I would have started by constraining the areas that were causing the problems. In order to put folds back in, I probably would have exported to zbrush. True that constraining from the hip to the knee was overkill.

My point is that constraining the problem areas will make them follow the figure. But take anything I say with a grain of salt. :-)

i forgot about the most important function that poser needs for dynamic clothing.

connecting low poly cloth with high poly cloth.

in movies they model a detailed jacket. then they model the same jacket without any details. then they calculate the dynamic cloth for the jacket without any details. then they add the detailed jacket on top. becaue its impossible to calculate cloth that has thickness,pockets,mesh details like wrinkles.

so again if there is a way to make one cloth folow the other cloth do it.

hi Ice boy,

there is. Normally used for a dynamic jacket over a dynamic shirt.

Just put on the two pieces of clothes, or the shirt first. Then create simulation 1, and have the first one (the shirt) collide to the character (say Vicky). Run the sim. Then create simulation 2, and have the second one (the jacket) collide to the first (shirt) instead of the character. Run that sim too.

Then render the animation, containing both sims.

But I don't agree you cannot calculate on advanced clothing. It's not that difficult to have a linnen T-shirt with leather bands stitched onto it, and so on. You can assign linnen and leather different material properties, like stretch resistance, density, air-damping and you name it. Same for double stiched pockets and the like. With just an advanced definition of the cloth, one sim does it all.

For example, I'm just testing right now on the issues above, using Vicky and JeanZ, all morphs included (say 60Mb). the JeanZ contain double stitched pockets front and back, belt loops, a leather belt, iron buttons (coming off right now, oops) and whatever. Due to some poke throughs, simulation requires 5 to 10 mins a frame in basic setup. Will be improved upon.

I guess studios use low-res versions first in order to get the underlying movements right, the poses, the flows, the muscle bulging. Then they shift to hi-res. Just assuming, that is.

regards

Dynaimc clothing in Poser is wayyy to slow to make. Not practical enough. We need more speed

On the subject of dynamic cloth speed - PPro 2010 introduced multi-thread bending, i.e. it uses multiple cores to solve the joint movement equations. But they didn't do multi-thread cloth sim.

I have a new machine with 8-cores and only 1 is used during cloth sim. I could get an 8x speedup without new hardware if cloth simulation was multi-threaded.

Massively multi-core (more than 1000 cores) is only 10 years away. All software will have to be written differently to take advantage of it. How you write software for less than 10 cores is very different than how you write for 50,000 or more cores. Software development is about to get very interesting - totally new techniques are necessary.

It would be absolutely brilliant with a multithread cloth sim in a future version of Poser or service pack.

A multithreadding cloth room sim. would be heaven :D

Would/Could it be possible to be implemented it into current PP2010/P8 via a service pack release?

frankly, at this time, the future for the cloth room is bleak. with few using it or teaching others how to use it, it has a stigma of being hard to use.. we've had it since version 5 people! 

I don't agree with that few people are using it. There's been a major upsurge in dynamic clothing content the past year or so compared to what used to be available. What I do agree with though is that can be tricky to get into, without finding good tutorials first. 

I don't find using conforming clothing all that much easier, unless I use a character without any custom morphs (standard height, shape etc), it still requires a lot of fiddling and morphing to get good results.

The cloth room could definitely use some love though, especially with things like multi core support and things like that. I don't know what could be done to make it more accessible for newcomers?

Cloth room is not difficult. Dynamic clothes are usually slower to work with than conforming clothing but then again, the results are usually much more natural. If you want to be ambitious then dynamics is the only way to go.

What I am worried about is that Posers cloth simulation engine seems to be somewhat lacking. It was already a used engine when they bought it and it has not changed since the beginning, or I am wrong? They have honed the routines so that the cloth room does not crash so easily, but otherwise it is the same?

Yet the research is going forward all the time. Ice-boy already showed us an example in one of his earlier posts of this thread.

http://graphics.pixar.com/library/UntanglingCloth/paper.pdf

If I understand correctly the paper above proposes "simple" solutions to both cloth gets pinched between body parts problem and cloth intersecting with itself problem. This working paper was introduced in 2002 and since then there has been many other steps forward.

Poser dynamics is slowly getting left behind.

Reinhold Pupu

one of the reason a lot of people dont use it is because there are nto enough free dynamic clothes.

i personal am trying very hard to give people as much dynamic cloth as possible. for FREE

I was told by someone who does know dynamic cloth that many conforming items can be used as dynamic cloth if the items have a hip.

a lot yes. but it depends on the mesh.

for example a lot of conforming clothes are not a single mesh. they are seperated even f doesnt look like that. try it out in a modeling software.

plus a lot of conforming clothes dont have good topology. not good IMO.

Quote - But they didn't do multi-thread cloth sim.

The cloth sim is a library that was bought in and wrapped. I'd speculate that the likely reason it isn't multithreaded was cost (parallelising that type of calculation is a non-trivial amount of work, assuming the supplier knew how to do it in the first place).

I love dynamic clothing far more than conforming. Conforming does have it's place, but for things like skirts, dresses, robes, sleeves and even pant legs, dynamic is the way to go because the cloth follows the figure's pose and the end result looks so much more realistic.

For the bodice and the waist/hip of pants, conforming is best IMHO.

Yes, dynamic cloth can be tedious to work with sometimes, but it is definitely worth the effort.

hi all,

while my promised tests are still running (current settings require over 30 mins a frame now), I'm going to spoil the multi threading debate in this dedicated post. Sorry.

Multi threading is a limited venue. It might speed up a process in a lineair way, doubling the threads cuts the time in half, but at the cost of quadrupling overhead due to interaction between threads or thread results. so there always is some upper limit where overhead grows faster than speed increase.

In the final rendering process, this limit is quite high, because calculating the image pixel color from polys, materials and lights does not effect those polys etc in return. It's a one way non-looping calculation. This is why GPU processing using over 1000 CUDA processors in your nVidia card still can be a gain (not for Poser yet).

In cloth simulation however, moving a vertex does effect the calculation of other vertices thanks to stretching and sheering, and this looping calculation limits the multi-threading severely at the algorithmic level. Currently 2 to 4 simultaneous threads might be the limit. A complete new algorithm (be my guest) might bring us 8, but thats really it.

And while running all my tests, Taskmanager tells me that Poser is using 25-75% of my 4-core machine. That is: 1 to 3 threads in parallel on cloth simulation, part of the time. So up till now my conclusion is that the Poser cloth sim process (just P8 in Vista-32) is as multi-threaded as can be, for a $200 program.

Of course I understand that people like to have the functionality of a $20.000 pack, and that other people like to pay only $2 for it. I'm happy with what I've got now.

And indeed, for calculating a simulation a very fast 2-core CPU is better than a slow 6-pack. For rendering it's the reverse. Life is one big trade-off.

More results to follow soon, be prepared...

hi folks,

as promised I’m going to spoil the fun by throwing in some facts, figures and observations from Cloth Lab (a special branch from Muppets Labs Inc).

At first I loaded just Vicky 4.2 to test her leg, from the issue on body parts intersecting each other, and on poses being feasable in real life. My finding is that the knee can bend up to 105* in a very natural way, while up to 120* the upper and lower leg start squeezing in the knee-pit but not having an unnatural result. Above 120* (the limit is 145*) the intersection starts limiting proper results, while my own legs start feeling rather uncomfortable with bends from 120 to 135. I can’t make more myself. So, I would like to consider every bend below 105 as relaxed, up to 120 as tight and over that as extreme and avoidable. The 145* limit is good for Android Andy, but that’s it.

Then I loaded JeanZ from 3DWizard, used it as conforming, and made the same bends. Again, up to 105* offered no problems but close to 120 the pose started to be unnatural as the thickness of the cloth made the self-intersection start earlier. As could be expected, the conforming clothes hardly folded and wrinkled which produced a very unnatural result, like constraining dynamic pants from hip to below the knee. It’s like a panty-hose.

Then I turned the conforming JeanZ into dynamic, using the build in Wardrobe Wizard conversion script, choosing for high resolution and keeping all morphs. This pumped to 5Mb obj up to a 60Mb pp2 file. The first trial run made all the bottons and nails pop off, so I made a soft-decoration group for them (constraining them to the cloth) and constrained a strip from the belt-area to Vicky’s hips, to prevent the JeanZ from falling off. Setting the drape to 5 frames, everything else was kept to default. One leg moved in a 30 frame animation from straight to a 90* bend upper leg and a 120* bend knee.

While frames took between 5 and 10 mins each to simulate and the 4-core CPU fluctuated between 25 and 75% usage on Poser alone, the pants started folding in the crotch area in a very natural way, and the knee area started folding later and stayed very natural up to 105*. Up to 120* the sharp folding as raised by Reinhold Pupu (dolherin) originally became visible. Is was clear that the cloth was pulled into the kneepit and started self-intersecting for a bit.

Then I redid the scene completely, and started to convert the original JeanZ to a lowres clothified prop without any morphs, using the same WW script and the usual cloth room steps. The 5Mb obj became a 12Mb pp2. Same setting for a soft-deco group and constraints, default cloth parameters again, frames again took 5 to 10 min each and the CPU ran 25-75% and even more on my 4-core machine, which means it has 1 to 4 threads active simultaneously. I’m on Poser 8, Vista-32 by the way. See my post on multi-threading above.

Like in hires, crotch and knee folding started right away and looked pretty natural up to 80* (frame 20/30). Beyond that, the pants became self-intersecting and not being able to make the fold, causing the issue that gave rise to this thread. From frame 24 (96* bend) results got ugly.

So the issue is a combination of self-intersection of the pants leg (not Vickys leg) due to the pose and a lowres pants mesh. A hires mesh suffers from self-intersection too, but at a rather larger angle (higher frame nr), and therefore can handle more extreme poses.

Lowres calculating in about similar times as hires did not supprise me that much. In the first place, the pants suffered from a “naughty vertex” which was off all the time and might have caused the long times in the first place. Without it, times might even have been 30 sec for lowres and 60 for hires, which is a difference, but I can’t tell now. Second, cloth simulation is a collision detection between two meshes, and reducing pants only but keeping Vicky intact might not have made a huge effect.

At last, I ran a simulation with all cloth parameters at 1/10th of their default values. This results in jeans made from a mixture of latex, silk and lace, and technically gave all vertices more freedom to move and settle. The result was a 5 times longer calculation time (2000 sec/frame instead of 400) and pants being torn apart in small areas or showing other artifacts not seen before. Not very recommended. Cloth parameters just should get as close to reality as possible, apparently.

Back to the original issue. Reinhold used the fold and artifact issue for raising the question on future development of the dynamic cloth features. No-one knows, it’s all a matter of time and money, or: user-base, user-request and competition. The latter has become more severe, from Daz Studio (half the price), Carrara (double the price) and Blender (free) all ramping up functionality fast. On the other end, most studio tools (Max, Maya, SoftImage, Cinema4D, ...) dropped their low-price varieties.

There is a thread in the forum on user requests, like “what about version 9” or so. It’s all about user interface and speed, library handling and bugs / stability, lighting and mesh decimation / subdivision. I just waded through all pages of that thread but I hardly ran into requests on dynamic hair, cloth or alike. Are we on a lonely island on Poser planet? On the other hand, improving dynamic cloth is not on top of my priority list either.

This does not imply that the dynamics cannot be improved upon. Although the current simulation works fine in non-extreme conditions, the paper referred to by ice-boy proves that revised algorithms can be utilized for handling crushed cloth in cramped knee- and armpits, and shirts being rubbed. This still leaves the question whether such a thing should get priority in the further development of a $200 program that – to my knowledge – has never been used for any 10+ minutes movie, music-clip, price-winning short, artistic DVD production or TV commercial. IMHO, it should not. It is on my wish list, but not on top. This implies that for stills, I’ve got to fix things in post. For 3D-cartoony animations I’ll have to find tweaks, and for photoreal shorts I’ve got to avoid extremes in front of the camera. Fine to me.

That’s all, for now.
Happy Posing.

Quote - In cloth simulation however, moving a vertex does effect the calculation of other vertices thanks to stretching and sheering, and this looping calculation limits the multi-threading severely at the algorithmic level. Currently 2 to 4 simultaneous threads might be the limit. A complete new algorithm (be my guest) might bring us 8, but thats really it.

The force calculations involved in cloth simulation are simpler than for molecular dynamics (springs, oopb, gravity, constraints, no long range forces) so the parallisation should be easier provided the distribution of vertices to threads/processors is reasonably done.

The "no long range" forces is important, as that allows division into a larger number smaller chunks, the limiting factor being the overhead of exchanging data between chunks.

This is the standard tradeoff in parallelising code, and in this case, I'd expect the optimal number of chunks to be much higher than 8 (given that most dynamic cloth has multi-thousand polys).

hi nruddock,

I see were you're coming from,  but I'm not buying yet. But please point me where I'm going wrong in my reasoning below. In the meantime, note that my main point is: multi-threading is limited, it's already there, and enhacing the algorithm will bring little net results.

• the average  size of a pant, shirt or table cloth is about 1 m2, and with a poly size of 1 cm2 (lowres) one gets 10.000 verts. In hires (1 mm2) one gets 1 million verts, so lets go 100.000 verts. Stretch forces will range say 1 - 2 cm, or 16 verts in hires to 2 in lowres, let's take 4 or so.

• when compared to rendering, the latter is a process with little overhead. Bucket edges (the long range force) are 1 to 4 (say 2) pixels on all sides, the geometry is simple (rectangular image) and the pre-process breaking the scene into tri's and determining maps is a one-off. Still, we don not use bucket sizes of 1 but of 32, packing 1024 pixels in one thread, for economic reasons. Given various discussion threads here at rendo, one might increase bucketsize to 64 or 128 in various circumstances, which combines even 16.000 pixels in one go (effectively reducing multithreading overhead).

• cloth sim has a longer 'long range force', as stated above: 16 but say 4 verts on average. Geometries are complex: legs and sleeves, open jackets, closed T-shirts so not that easy to divide, and the pre-process is iterative instead of one-off. Therefore, overhead is relatively larger than in rendering. Thus we might combine 10.000 to 40.000 verts in one thread instead of 1000 to become economical (that is: more threads do not reduce total calculation time). Just a guess.

• so from verts-per-cloth and verts-per-thread I'm under the impression that the economical (not the technical) limits are between 2 for a lowres high complex mesh to 16 for a highres simple mesh, even 32 or up maybe.

• what I'm seeing in taskmanager when simulating is a fluctuation between 1 and 3 threads (25-75% on a 4-core engine) and very incidentally a 4th thread. Hence, I consider my reasoning and my observations to be in sync. I like that.
  Therefore, more threads in parallel will occur even less and therefore pumping up the parallism will hardly contribute to shorter reallife net calculation times. This contrares to rendering, where one will get 100% CPU-load for a serious time on whatever machine. In other words, investing in more advanced cloth sim algorithms and throwing money at 16-core machines or so may not pay off that well, as it comes to speed. And... multi-treading is already there.

So, despite the details, I'm still holding on to my main statement in response to the various multithread and speed remarks in this rendo thread. I maybe wrong, but I'm not convinced yet.

regards
Ronald 

I found under Poser 7 that draping only works properly for a figure at x=z=0, else the draped garment pulls to one side. I suspect that draping was meant for one figure who is the centerpiece of a scene, not for several figures in a scene. I found this when I made a model of a surgeon whose operating gown's skirt was draped, when I tried to have 2 or 3 surgeons in a scene, not only one as a centerpiece.

Really?

Hmm..  I've made walking scene where the character started at an offset position and it worked pretty well. (One character with a dynamic skirt and another with a sorceress/wizardress dress)

(bm)

hi Anthony,

I didn't test under P7, but in P8 everything works fine in any position, as long as you start with a decent fit (parenting the skirt to the right surgeon, constrain some verts at the shoulder, try to prevent poke-troughs by having the surgeons in a reasonable pose). And of course you need three simulations as each skirt collides with a different surgeon.

The effect you describe happened to me in the early days too. I had an animation starting at 0,0 in frame 1, then moved everyone into position in frame 2, and life started from frame 5 or so. The movement from F1 to F2 introduced extreme effects on the cloth, as you can understand.

Draping just adds frames before F1, and leaves them out of the result. Unchecking the "drape from zero pose" might have some effect too.

Suggestions anyone?

Quote - hi Anthony,

I didn't test under P7, but in P8 everything works fine in any position, as long as you start with a decent fit (parenting the skirt to the right surgeon, constrain some verts at the shoulder, try to prevent poke-troughs by having the surgeons in a reasonable pose). And of course you need three simulations as each skirt collides with a different surgeon.

The effect you describe happened to me in the early days too. I had an animation starting at 0,0 in frame 1, then moved everyone into position in frame 2, and life started from frame 5 or so. The movement from F1 to F2 introduced extreme effects on the cloth, as you can understand.

Draping just adds frames before F1, and leaves them out of the result. Unchecking the "drape from zero pose" might have some effect too.

Suggestions anyone?

I'm sort-of picking up that English is not your native language, but after a chuckle over this medical board set all over your cloth room, I tried to puzzle out what you meant by "surgeon"... certainly not that individual in green outfit and mask with a scalpel in his/her hand?

hi,

as in my thumbnail, Europe, Netherlands so I'm Dutch, mixing up US and GB (and other) English all the time but I can do German, French and Spanish and a very little bit of Greek and so, plus a dozen computer languages too, although my French-to-COBOL translations were never that succesful :). MSc in math and physics (30 years ago), currently working as interim finance manager in large scale projects in-a-state-of-panic. Great fun. But all remarks are welcome, I won't stop learning till I'm dead or so. More "About Me" on my personal site.

Yes, surgeon is in green with a scalpel, or worse. As is Anthony Appleyards post above, he has modeled some of them with an operating gown's skirt and put two or three in one scene. His words. I guess the patient in between might have a dynamic sheet for some coverage as well.

have fun, best regards,
Ronald