Quote - aRtBee been following along, even on the weekend. I have nothing to contribute so rarther than say "oh, ah", I stay quite. But that doesn't mean I haven't found the work you guys have done totally fantastic, and a good historical read too. I found lots of great tips, and I'm not so scared or confused by the morph brush now oddly enough.

Couldn't agree more General. Like you I lurk and learn.

Very interesting thread, will read over the experiments and results more carefully later, just wanted to add a couple of points I've learned along the way, particularly when simulating for animation.

1. Do it in stages, especially if its a long scene or complicated pose. This could also apply to problems like the seated poses that have given some folks problems. Click through your simulation to find the last "good" frame, use the group editor to spawn a prop, now you have to duplicate your scene and simulate using the new prop. Most importantly you can edit or add to constrained groups, can prevent flattened or sat on areas trying to "swallow" chairs etc.

2. Fake it! Use props to help, in the attached vid I it to appear as if Freak was straining against an invisible layer. It needed 2 shots and 2 simulations, Both made with Freak lying on his back, embedded in a hidden box prop. As BBhas already noted if no verts touch on the cloth and collision surface, the sim fails, so for the freak face shots I replaced nose and other tricky features with scaled down primitives. On another occasion I used spheres parented to a models legs to prevent a dress from falling back too far.

http://www.youtube.com/user/VJflickeringlight#p/u/26/8wawdBTsVTM

Dynamic part in the first few seconds. animated materials are a slight hack of BB's Nacelle shaders

Actually - I've found - that the longer the sim and the more frames it takes to get to your finished pose yields better results. Seems that if the cloth can move slowly it moves in a better way ;o). Sure, it takes longer, but it's better in the long run. Of course, your cloth settings factor into this...lol. If they're wrong, nothing's gonna make it look very good.

Laurie

TIP:

If you change the settings for static friction or dynamic friction in 4. Dynamics Controls, do NOT check the Collision Friction box. If you do, it will revert to the settings for static and dynamic friction in 2. Cloth Objects where you set the collision depth.

Laurie

TIP2:

If you want to have your cloth stretch, but retain it's basic shape, lower the Stretch Damping setting. If you want your cloth to stretch and stay stretched, raise the Stretch Damping setting. Stretch Resistance is how much or how little it will stretch. Stretch Damping is the amount that it will snap back to shape once stretched. A low setting will snap it back some. A high setting will leave it stretched.

If I'm getting annoying just let me know ;o).

Laurie

Synchronicity. I just resumed work on an image I have been troubling with for 3 years...because I want dynamic robes flowing like water.  And here is this thread, with all of you wonderful people (including Mr Wizard himself: BB, and one of my newest heroes aRtBee; the two of you make my jaw drop in wonder) working the same thing.  Wow.  Thanks.

This is awesome and I am hoping for more.  If I can contribute I certainly will.

I've been over that SM tutorial on the Cloth Room and its effects several times, and have used those settings as a jumping off point to get some good effects.  But this crystal ridge, and the cloth self collisions... FRUSTRATING! Doesn't help that I am using conforming clothes that I have just pulled in the OBJ to make dynamic... but still.

hi, back again, was just updating my own site and doing some Cloth Room tests.

Laurie, you're doing fine, please continue. Stretch indeed is like an old iron spring, first you need some power to make it longer (resistance), and when you let it go it takes a while before it's back to its original length (damping). I'm going to find out what's behind those 50 and 0,01 numbers, in terms of units and real life. I intend to do Friction this evening. 

3Dave, well stated.
Your 1) Stage it! is so true, next to my findings tha animation shots should not last longer than 3 to 4 seconds anyway t make an intersting story. We live in the TV and internet age, shots are fast.
Your 2) Fake it! just mean: thins as a pro, as these guys don't have the time to get the full monty either. The difference it that they have a day to serve the customer, and I have only my spare time.

First, I'd like to note a bug (feature?). When clicking the Reset button in panel 4, my value for Stretch Damping is NOT reset to the default 0,01 value. I'm on P8SR3. can this be confirmed? Is it also the case on P7, other P8-SR's or PP2010?

Now, let's consider panel 1, Sim Settings, in more detail. In fact it covers two areas, 1) frame handling and 2) calculation handling.

1) frame handling.

It seems so simple, it takes the figures pose in frame 1, runs a number of drape frames to make a proper cloth fall over the figures body in a relaxed pose, then follows the figure when is animates from frame 1 to any end frame, and then inserts the result - excluding the drape frames - into the animation from frame 1 on.
And there is a button to do the drape only, without the time consuming sim. This helps you to determine a decent amount of drape frames. 

Now this is fun: just put some other value for Start Frame. Say your figure animates from frame 1 to 60, and now you simulate from frame 21 to 40. What will happen?

In my P8SR3, the drape still runs against the figures position in frame 1, then the simulation runs against the poses and positions of the figure in frames 1 to 20, and then the result is mapped into frames 21 to 40.
But since the sim determines the cloth vertex positions in world coordinates, the cloth in frame 21 will be positioned to fit the figure in frame 1 while the figure itself is moved away 20 frames. This is the nightgown chasing Vicky.

Can this be confirmed on other Poser versions? Can anyone think up a use for this? Because I think it's a bug (feature?). That is: it would be quite handy to run test sims on small ranges of frames before doing the whole one. But then, the sim should run against the figure positions in frame 21-40, in the example above. I wouldn't know about the drape.

2) calculation handling

The sim setting's offer three checkboxes and a steps-per-frame setting. The defaults are for hires tablecloth over a simple lowres prop (so the cloth can easily follow the props curves), and for minimum calculation times. By changing these settings you enhance the calculation mechanism, and the intention is to provide a more natural looking result.

For instance, when you've multiple cloth-objects (panel 2) colliding to each other (eg blouse over skirt), or the tablecloth has massive folds which collide to each other, it's well advised to tick the cloth-to-cloth checkbox.
And when you've got lowres cloth over a highres body, the cloth will face troubles to follow the curves of the figure, so it's advised to tick the object vertex against cloth poly.
With 2 steps per frame, it's like the algorithm looks not only at frame 15 and 16 positions, but at 15.5 as well. So when the figure is really moving you might get better results by increasing this amount mildly. It's not doing a complete subframe assessment I guess (I can't look inside) as calculation times do not go up linearly.

So I questioned: can these settings prevent the poke-through errors we were facing in the earlier posts? What does the enhanced quality result really mean?

Therefore I did a simple experiment: took a cone, scaled to 400% in Y-direction which turned it into a needle, and started to drop a piece of cloth right on to it. I noticed the following:

• at default setting, the cloth falls right through the needle

• ticking the checkboxes helps, for a few frames. The pokethough is not prevented but postponed

 - increasing cloth stiffness (fold / shear / stretch resistenace and stretch damping) made a difference. The stiffer, the more it seems to prevent pokethrough. Untill I prolonged the animation / simulation period. Then it appeared again that the problem was not solved, but postponed. On the other hand: this stiffened up kind of cloth becomes less and less realistic and elegant.

 - increasing collision offset (more on that in a next post) helps, as it thickens the cloth and puts it at some distance from the figure. At a firm thickness , the needle can't penetrate any more indeed, at any point in time. But again, then the results don't look realistic anymore. Real life favors silky night gowns over carpet-based ones.

So, what have we got (just thinking out loud).
Real cloth can be fibre weave based (leather, latex, fleeze are not. Sweaters can be knit). The fibres have thickness and characteristics (which differ per thickness) and the weave can be loose or tight. The fibre thickness and tight weave might prevent a needle to stick through.
Poser virtual cloth has a fibre-concept based simulation, as follows from the literature in earlier posts. But the fibres have no thickness (there is no parameters for this). It's only the fibre behaviour which is derived from the cloth parameters. Even leather and latex are treated as weaves. So, I guess, it wouldn't be that difficult for a needle to poke through. The algorithm can't stop that.

Hence, until the people who might look at the algorithms and vertices behaviour themselves come up with a different view, the best we can do is postponing the problem till a frame we're not interested in. Or, the other way around, we've got to chop our animation into pieces were each piece behaves properly. 

Which was exactly one of 3Dave's suggestions. And setting the calculation options might be of help, and 'solve' the issue in short animations.

And now for panel 2, cloth-objects (or: sim items).

First, I had to found out hat was really meant by collision offset and depth. So I made a very large box (100% scale in X and Z, 10% in Y direction), took a square piece of cloth and dropped it. By using camera zoom in and by moving the box up in the final frame, I could what happened on varying those 2 values. 

No miracles here: even when the box slowly moves up when the cloth falls down, the cloth ends up some distance above the box. This is the OFFSET distance, in cm. When you think the "bottom" or inner surface of the cloth is on the figure, and the "top" layer or outer surface is the cloth itself, then OFFSET is the effective vritual thickness of the cloth. The minimum is 0,1 (= 1mm), the max is 10 (cm).

So again, like the parameters, distance is in cm.

Now, what does Depth do then? The manual and some SM-tutorials (like http://my.smithmicro.com/tutorials/418.html) suggest that it does what Offset shows to do. Someone has been mixing up things.

Seemingly, it did nothing. Until I made the box quite flat (2%, or 5,6 cm to be precise), I kept offset at 1 cm at varied depth. I saw the cloth falling (at a constant 8.8 cm/frame, thanks to airdamping) while the box moved slowly upwards. And at depth values of 1,2,3,4,5 and 6 the cloth ended up correctly, 1 cm above the box and moving up too.

Until the depth value became 7 or more (max = 10 cm). Now it disppeared at impact, and immediately reappeared... at the other side of the box, at 1 cm distance, and moving up with the animation.

Why did it move position when the depth became 7 cm? Well, since the cloth resides at 1 cm above the box normally, and the box is 5,6 cm thick, looking ahead 6 cm would not see the other side of the box, while looking ahead 7 cm would.
From this i could also infer that first: the cloth was put at 1 cm offset at a response to the collision, and second: the look-ahead for the other surface.

After that, the algorithm draw the wrong conclusion and warped the cloth to the other side, and above that: the cloth stopped falling down from gravity but started to move up with the box. 

Like the offset, the depth is measured from the cloth (outer) surface down towards the figure.

According to the tutorial above, the look-ahead method attempt to make more natural results faster. When you set the value too small (less or equal to the offset) it becomes ineffective. If you set it too large, it starts responding to pieces of the figure which are irrelevant to the simulation as it should be done. And vice versa, if other pieces of the object become too close and inside the look ahead range, they might disturb the result as well. Animations might do this, with hand close to the body. in that case: reduce the depth.

I have not tested yet for multi-figure situations (figure sitting on chair with cloth inbetween). Will do.

Then there is friction, static and dynamic. These have equivalents in the parameters section. The parameters address the characteristics of a specific dynamic cloth-object-group. The values in our cloth-object settings address the whole cloth-object, hence: all dynamic groups of that cloth-item. You can tick the checkbox at parameters, as Laurie has posted recently. Then the cloth-object values are used. When unticked, the cloth-object-group parameter values are used instead.

Why would that be? It suggest that one sets values at the object level first, till one likes them, and then fine-tunes for underlying groups individually. This implies that friction is an important factor in the simulation results. otherwise: why take this trouble for these parameters only? To be investigated upon.

Note: when you build your cloth from several cloth-objects (just go on clothifying object-portions to the list), the settings will hold for the entire set, not per cloth-item. So when a blouse and a skirt are added to the list, both with have the same offset, and depth, etcetera.

Note: I tried to take a conforming dress having hip, abdomen etc as in Vickys geometry, but also skirt and other elements that were not in Vickys structure. The first group of elements could all be clothified to the list, but the others could not. I could select them for clothification, but nothing happened after the [OK] button. Might be an OBJ thing. To be investigated upon.

Ticking the Start Draping from Zero-pose box implies exactly that. At the beginning of the Drape, the figure (and not the cloth or dress!) is set to the (in)famous T-bone pose, and while the dress drapes over the figure, the figure itself is animated towards the pose in frame 1. This of course does nothing for props with no zero-pose at all (like a table), and does nothing for those animations which start in zero-pose at frame 1. But, from the above, you can infer there is no need to do that. On the other hand you can understand that the more your frame 1 pose is off the zero pose, the more drape frames you need to start your animation / simulation with a properly fitting dress.

Finally, of course, you have to reveal the collision target aka 'the figure'. Choose Vicky, and select to ignore hand, feet and head to speed up calculations. But do add shoes when the dress suggests collisions, deselect arms for sleeveless dresses, and so on. Handle stacks of sims the way they appear in nature: if the blouse in sim A is over the skirt in sim B, then include the skirt as a target in the blouse sim. And so on. It does not harm that much to add in a bit too much geometry. It can only slow down processing a bit. Or it can disturn the results when geometries become to close.

For the sake of it, I'd like to share some observations on simulation calculation times. It appears to me that as long as a dress fits or falls in a smooth way, it runs fast whatever the settings, although the I've more enhanced the calculation, the more it takes.
When collision and disturbances kick in, simulation really slows down. But... an effect of the enhanced simulation settings in a lot of cases is, that the dress runs smooth for far more frames in the animation. As a result, simulations with the enhancements ticked frequently run faster than those with the options unticked.
Hence, the idea that the simulation options slow down the calculations is not my observation in general. Sometimes it does, frequently it doesn't.

So, I'm interested in your findings.

Thats it for panels 1 and 2 now. There is more to investigate. There might be bugs around, or non-understood features. We have to ask the SM people. Just hold on, we're moving ahead. Check upon me, I might be wrong. Fill me in as well. I'm not the all knowing guide through this swamp. But perhaps I'm just one stone ahead, like some others as well. Or was it the alligator I just stepped on? 

Have a good night.

And for now, my first attempts to master Friction. Some things in life are simple: the implementation, the concept, the experiment and the physics theory. beyond that, I'm on alien grounds. But let's present my current findings first.

Poser implementation

Friction comes in two flavors (static and dynamic) and both can be set in two places, as was flagged already by Laurie and other posts above. They can be set for each Cloth-object-group individually, and for the Sim-Object as a whole. By (un)ticking the box in panel 4, below the Play Simulation button, you can choose which ones to use.
This way you can establish a rough setting first for the whole Simulation / Cloth (remember: those settings address all cloth-objects from the list, there are no settings per cloth-object). Then you can fine tune the behaviour per cloth-object-group.

Friction is important for cloth room. While density (gravity) and air-resistance address the interaction between the cloth and the room itself, friction addresses the interaction between the cloth and the figure it collides with. Simply stated: when the cloth vertices hit the figure in a perpendicular way we're talking collision, and when they interact in a parallel way, we're talking friction. 
So friction is as relevant as collison. Now you (and me myself) can understand why the cloth-object settings in panel 2 address both in the options. 

The concept

When a piece of cloth lies down on the floor or on something else, and a force - like gravity - is applied on it to drive it forward, then the contact of that cloth with the floor will work against it. Up till some limit the cloth won't move at all, when that limit is exceeded it will move but will still apply a force against it. The latter is called dynamic or kinetic friction, and that limit is called the static friction. You might infer that dynamic friction should be quite less than static, which is correct (although Wikipedia reports on some exceptions in the laboratory).

The experiment

Easy to do at home. Clean up a smooth long table, put a piece of cloth flat on one end and tilt the table. Until some tilt angle the cloth will stay put. That's static friction.Then the tilt becomes larger than that, the cloth starts to move smoothly. Thats dynamic friction working against the gravity pulling it down.

So this will be our Poser experiment too. Large long thin box, and a piece of cloth on one end. Start just above the box and give it some (say 10) drop frames to end up on the box.

Now create an animation, say 240 frames in total, and make the box rotate along the Z-axis in the first 120 frames, up till the angle of interest, say 30 degrees. You have to do it this slowly, because otherwise the cloth will get launched. And it's a good idea to zero out Air Damping.

First turn down Dynamic Friction, till its lowest 0.0001 value. Then start playing with the Static friction, till you find that one value that starts / stops the cloth from moving when the box it at its largest angle, and the cloth is on top. Just a fraction less and the cloth starts moving. That 'critical value'. Each angle of interest has its own critical Static Friction value, and vice versa.

At low angles, the values are less accurate to determine. These are mine:

angle static

10 0,050 - 0,045
20 0,060 - 0,055
30 0,1205
40 0,2363
45 0,8744
50 > 1, the max value 

A similar experiment can be done for Dynamic Friction. Same setup, take a Static Friction value a bit below the limit, so the cloth will move but not before it has reached the top at frame 120. Vary the Dynamic Friction value and note the frames (the time) that the cloth passes halfway and the end of the box. Higher friction values make lower speeds and therefore larger pass-by framenumbers.

After measuring the size of the box we can infer the speed, meters per frame or per second, as a result from the dynamic fraction, at that angle limit of the box. This is a shipload of details, so I'm not posting them (yet).

In the meantime, I notices a few effects while playing with the parameters.

• Density has no effect on friction, at the larger angles. This is physically correct. but it does have effect at the smaller angles. 
• The stiffness parameters (fold/shear/stretch) do not have effect, until the stiffness passes values like 400. 
• In some cases with large parameter values, the cloth started rotating while coming down. 

I have no physical interpretation for any of these. It might be something in the simulation algorithm.

The theory

Wikipedia has good info on this. Friction is a force, which works against the force that drives the cloth over the box surface. The friction is proportional to the force which presses the cloth onto the boxes surface.

When the box is tilted, the driving force from gravity reads F = d * S * g * sin(z) for density d, cloth surface S, gravity acceleration g and angle z with the horizon (flat = 0). And the friction reads F = f * d * S * g * cos(z) for friction parameter f. 

At the angle where static friction just prevents the cloth from moving, both forces are equal, and all collapses to f = tan(z), having most values between 0.3 and 0.6 in real nature. Values for f larger than 1 are rare.

For dynamic friction, we've got Coulombs Law stating that the force is independant of the sliding velocity. So, when the cloth moves, we should see a constant acceleration of the cloth with gravity force F = d * S * g * sin(z) minus friction F = f * d * S * g * cos(z), over the cloth mass dS. Hence, the acceleration reads g * [sin(z) - fcos(z)].

This is like free fall, so we might expect a falling speed v = g * [sin(z) - fcos(z)] * t (t for time) and distance s = 1/2 * g * [sin(z) - fcos(z)] * t^2.

Correcting for unit conversions, and noting that the friction parameter is a ratio between forces and therefor unit-less, we should be able to interpret the Poser measurement results.

The issue

Will, my poser cloth room experimental measurements do not fit physical theory. That's it, plain and simple.

The static friction angle vs critical value list does not follow the simple f = tan(z) or anything alike. The dynamical friction values do lead to neat distance vs time relationships, but not the one from Coulombs Law.

Hence my queste for this moment is: what rules do the Poser friction values follow, perhaps even why, and how do they relate to the real world. Suggestions welcome.

I started to write what you wrote a couple times, but I despaired of having to type all that. Thank you.

Meanwhile, I have found the same. The forces don't make sense with respect to the real world. And - rotation occurs spontaeously for no reason, because some vertices experience critical force and go from static to dynamic friction, while other vertices remain static. At random times, one part will happen to have more stuck vertices than the other, creating a torque. Once rotation sets in, inertia keeps it going.

High stretch resistance tends to make it less likely for a vertex to start moving while its neighbors are still stationary. But it's still so unpredictable that I'm not sure anything useful comes out of it, especially if extremely high resistance is required and ends up cause the cloth to behave like cardboard.

(bookmarked)

I'm no old hand at the cloth room, but one tip I've heard from apparently able users, but have not seen mentioned in this thread is to think real-life when planning your animation, and the simulation will go easier.

Meaning if you want a complex sitting position in your final frame, do a couple of "partway" poses in the progress of the animation time line. This supposedly will help the software figure out how to get both figure and cloth get to the end position.

I haven't personally tried this, because at this point I haven't done anything really difficult, pose-wise, in the cloth-room. Perhaps someone else can verify.

hi all,

just a quick word from a busy (aRt) Bee, right from the Cloth Room in Muppets Lab.

I'm still working on cracking this Friction thing. Up till now I wasn't that succesful in understanding Static friction, but last evening I found the magic in Dynamics. This is it:

in the cloth-slider-over-the -tilted-box experiments, the cloth is driven by an acceleration

a = Gsin(z) - Dcos(z) for tilt-angle z (with the horizon, as set in Z-Rotate), for dynamic friction effect D (under investigation) and for gravity acceleration G = 9.8 m/s2 = 1.0889 cm/f2 when switching to the Poser units cm and frames, at 30 fps. That's basic mechanics.

The question is: how does D in this theory relate to the setting in the Poser cloth parameters?

Well, it IS the setting !! The Poser dynamic friction is not a dimensionless ratio between forces as in the physics literature, it is the resisting acceleration from the cloth on to some surface, under Earthy gravity, expressed in Poser units: cm and frames. So, when you set D to the default 0.1, the cloth on the tilted box is accelerated with 1.0889sin(z) - 0.1cos(z), which determines its speed and displacement.

Notes:

 - it's all within measurement accuracy, which is not very good for this experiment.  Frame numbers for passing markers are 0.5 off by definition, differences between them are used for deriving speeds, and differences between speeds are used for acceleration. Then this result is inaccurate by 10 to 30%. All my results were within these limits. Even more, when taking different angles z and changing D such that the same acceleration resulted, all measurements showed identical results up to the frame numbers.

 - cloth density has no effect on these findings, tested from 0.001 to 0.500

 - when Gsin(z) - Dcos(z) < 0 the cloth stops moving, or doesn't even start. So, dynamic friction plays the static part too. This implies at standstill for the static experiments: D= G*tan(z); so that literature values for static friction, minus 10% (as G=1.09), are good estimates for D in Poser. Life is beautiful.

 - hypertextbook.com/facts presents acceleration and static numbers for human skin and cloth-to-cloth like info. These (minus the 10% on the static numbers) vary between 0.65 (skin to metal), 0.70 (skin to paper, cloth to cloth) and 0.75 (skin to plastic). This makes the Poser default 0.1 for dynamic friction far to low.

 - I expect a minor effect from stretch, as gravity stretches the cloth, and therefore it moves the center of mass. I then guess that the extra Static friction is here to prevent the entire cloth from moving as well.

 - Static friction has no effect, except for low dynamic friction (<0.1) / small tilt angles (,20)/ low speeds (I needed >3200 frames in animation/simulation). From this and the above I infer that static friction is something extra, having noticeable effects at zero or low speeds only. To be investigated. Which is what I'm up to right now.

See ya.

i think there are some bugs or problems with the contrained group. the contrained group is when cloth sticks on the surface correct?

well somtimes the mesh(cloth) explodes. or vertices jump out. the ones who were selected as contrained groups.

i also tryed a shirt that is very close to the skin to select as a contrained group. the whole shirt. so in away it would act like a confroming cloth correct? well sometimes it doesnt work and poser crashes.

issue confirmed.

"... the contrained group is when cloth sticks on the surface correct?"

That's what we expect. Not what we observe. At this moment, the gap between those is as deep and wide as the Grand Canyon. Vertices are going wild sometimes. All contributions to bridging the gap and enhance our understanding are very welcome.

In the meantime, this thread already contains various suggestions that at least might postpone the collapse till frames far later in the animation.

first i changed quads to tris. then i used catmull-clark subdvion on top and got this.

@ice-boy

bagginsbill has generated a series of mesh structures, for various sizes and densities.

So please make your mesh structure available to us, in the same sizes and densities.

@all

during my investigation I've stumbled upon the efforts of OptiTex in the market of cloth design and animation, from 3D simulation to physical measurement devices, from pattern generators to fabric utilization, the whole lot.

OptiTex also plays a role in a 3DS MAX cloth plugin, and at the moment they support dynamic clothing for Daz Studio (as a vendor over there). In the Rendo freebie section, I've seen textures for those clothes coming up recently. So, some external pressure is building up for SM, perhaps some reconsideration of Cloth Room might be an idea after all.

from what i understand Optitex doesnt support OBJ?

this is not good. i hate this. i can not use dynamic clothng from Daz in poser.

Quote - from what i understand Optitex doesnt support OBJ?

 

this is not good. i hate this. i can not use dynamic clothng from Daz in poser.

I think that is deliberate, Optitex technology and dynaqmic cloth are new to Daz, only added in the last year or so, so both sides are probably trying to optimize sales for the DS plug-in.

OptiTex hardly supports common 3D formats at all, but does DXF. Poser imports DXF.

Poser can't handle DS lights, cameras, shaders and the Mixamo and aniMate features, so why should it handle DS dynamics?

This from the DAZ forum:

Here are some commonly asked questions and their answers regarding the new dynamic clothing plugin and content for DAZ Studio: 

Q: Can I create my own dynamic clothing? 

A: No, not currently. A separate dynamic clothing creation tool is required for you to do this. This tool is not yet available, as it is still in development. DAZ 3D has been able to create clothing only with help of the OptiTex pattern creation team and their internal tools. The release of a content creation tool is of critical importance to DAZ 3D, and we are doing everything we can to help expedite the release of this tool to our market. Meanwhile, new clothing items will continue to be released as they are developed by outside resources. 

Quote - OptiTex hardly supports common 3D formats at all, but does DXF. Poser imports DXF.

If you read carefully, the DXF is for 2D pattern import into Optitex's creation program. I'm sure I've seen mention of people exporting OBJs from D|S, but can't remember any mention of how well such exports did in Poser or if there were any gotchas (like the need to weld etc.)

Somewhere in the Marvelous Designer material there is talk that they will possibly be involved with DAZ's dynamics when the next major DS release comes out.

OptiTex is a very expensive program, and obviously have a vested interest in keeping things as proprietary as possible.

look at this. do i see right. a quad becomes a triangle when he bands?

ice-boy...if you had been paying attention to the entire thread, that was already stated. The sim treats quads like triangles. Just how it splits them though is up for debate ;o). I'm still not sure if it makes X tris (which I think it does treat it like X tris just by the looks of it) or diagonal tris (which I doubt).

BB also stated that it treats each quad like a membrane, splitting it up into tiny pieces, but I think he meant in the rendering and not necessarily the sim ;o).

Laurie

Quote - ice-boy...if you had been paying attention to the entire thread, that was already stated. The sim treats quads like triangles. Just how it splits them though is up for debate ;o). I'm still not sure if it makes X tris (which I think it does treat it like X tris just by the looks of it) or diagonal tris (which I doubt).

BB also stated that it treats each quad like a membrane, splitting it up into tiny pieces, but I think he meant in the rendering and not necessarily the sim ;o).

Laurie

its hard to read every post.  

you never miss a post in threads?

Yep. What Laurie said. Poser sim turns quads to diagonal tris. Firefly turns quads into a membrane and renders a full 3D curved surface touching all four edges.

Quote - > Quote - ice-boy...if you had been paying attention to the entire thread, that was already stated. The sim treats quads like triangles. Just how it splits them though is up for debate ;o). I'm still not sure if it makes X tris (which I think it does treat it like X tris just by the looks of it) or diagonal tris (which I doubt).

BB also stated that it treats each quad like a membrane, splitting it up into tiny pieces, but I think he meant in the rendering and not necessarily the sim ;o).

Laurie

its hard to read every post.  

you never miss a post in threads?

but you never seem to read any post. (and thats why you get shouted at)

he folks,

lets try to keep this thread open. Personal things in the site mail, please. Don't attack.

I don't even recall all my own writings all the time in this thread, let alone the other ones.

erm wasn't attacking. that wasn't even close to attacking. that was an observation...

an attack gets very insulting for starters....

I was not attacking anyone! sheesh...

I do miss replies ice-boy...but I do try to read back thru what I've missed so I don't ask repeat questions. But I do miss stuff, yep.

edit: perhaps it would be better if I keep my yap shut from now on then no one can misconstrue anything I say. Would that be better?

wanders off mumbling about touchy fg ppl...

Laurie

Um... but ice-boy actually said this test was in Blender. I don't see that anyone said any such thing....

Quote - Um... but ice-boy actually said this test was in Blender. I don't see that anyone said any such thing....

which would be great....if we were using Blender.

Well, I do (use Blender, for making clothes and playing with sims). Actually an interesting observation to make, ice-boy... mind you, I find more dissimilarities to Poser than similarities. The Blender cloth sim has "pins"... wonder what the Poser equivalent to that would be

Quote - > Quote - Um... but ice-boy actually said this test was in Blender. I don't see that anyone said any such thing....

 

which would be great....if we were using Blender.

did i writte that we need to use blender? i just wanted to show that its not the quads who are the problem but poser's coth room.

yes you will now say but this is what we have.  i know.i knooooooooow.

but now that we know what needs to be changed we can report it.

hi all,

just from my previous writings in this thread (saves you the re-reading):

The Poser Cloth sim is a simulation of the behaviour of cloth, as being a weave of fibres - even when thats wrong, in case of leather, latex, etc. In the translation of the mesh structure to the weave/fibre structure to be simulated, not only the vertices of the mesh but also the mesh topology itself plays a role. A quad mesh produces results slightly different from tri's and so on.

This was observed at various points in this thread, but was also noted on poserfashion.net in 2002 (Poser-5).

The thing is: we do not know yet what the effect exactly is. That means: to what extent do issues in cloth room relate to the mesh structure, and might be catered for by re-topoligising.

So, when a quad-based shirt presents an issue, the question is: does this issue disappear or change when the same shirt in the same animation etc only has a different mesh-topology (in the same Poser Cloth Room).

I'm sure quads behave different in the cloth sims in Poser, Blender, Maya, Max, SimCloth, OptiTex, Marvelous Designer and you name it. But please help us to get around the issues in Poser Cloth Room only.

That is: does retopoligizing really helps against breaking polyes and wild vertices in lengthy animations in Poser Cloth Room. And which one, and why, and to what extent.

Now, where were we - yes, the cloth room.

Drives me mad at times as well. Last item of clothing I made draped beautifully. The most recent? Looks dreadful...lol. I'll try converting it to triangles and see if it behaves better...lol. Thing is, this most recent item is just as dense as the dress I made last week. Go figure ;o)

Laurie

back again from the dungeons of Muppets Lab, Friction Research section :). From doing an awful lot of tilted plank and sliding cloth experiments, the physical well understood

a = Gsin(z) - Dcos(z)
for resulting acceleration a, gravity constant G = 1,09 (= 9.8 Earth value * 100 cm per meter / (30 frames per second)^2 ), tilt angle z and dynamic friction D

is a close enough approximation of the measured results. So, our Poser cloth parameter for Dynamic Friction can be set to real-life values for cloth and skin, which ranged from 0.65 (skin to metal) to 0.75 (skin to plastic).

For those who want to redo the experiments, a far better approximation of the results was found as a = G^2 * [ sin(z) - D*cos(z) ] for which however I don't have a proper physical understanding. But since Poser is not a science lab and G is about 1, the statement that we can do with reallife values is not that far off, and the best workable.

It was also observed that the formula did not hold very good at low cloth speeds, where also Static friction became a factor of influence. It was not at higher cloth speeds. It was observed too that no value for Dynamic friction could bring the cloth to a stand still, nor could prevent it from moving. Only Static friction could do the latter.

In other words, it's Static friction at zero speed, some mixture of Static and Dynamic at low speeds (1-10 cm/frame) and Dynamic only for higher speeds. The figure above intends to give some idea of this.
In the mixture, Static became noticeable only at low Dynamic values (< 0.1) or at Staitic values close to the critical one, where it prevents the cloth from moving at all.

The Static friction parameter could be measured by just tilting the plank until the cloth started moving. Higher friction means a larger angle, so each angle has a critical value for Static. Any value below that will not prevent the cloth from moving, then the speed increases, the effects of Static fades out while the effects of Dynamic kicks in.

Two issues in here, on the mixture at low speeds:

1. low speeds at low Dynamic friction is very hard to do measurements on. It either requires very small tilt angles or precise observation in the few frames after the start of the cloth movement. Not very accurate, that is, and therefore all conclusions get drowned in a sea of measurement errors.
2. unfortunately, the low speed 1-10 cm/frame range is the one for clothes under normal moving conditions. Bad luck.

The values I found did not resemble any physical meaning to me.

angle theory found

 5 0.0875 0.0105
10 0.1763 0.0295
15 0.2679 0.0400
20 0.3640 0.0550
25 0.4663 0.0700
30 0.5774 0.1278
35 0.7002 0.2000
40 0.8391 0.5757
45 1.0000 0.8625
50 1.1918 0.9480 

This means that at a tilt angle of 30 degrees the cloth started moving when the Static friction value came below 0.1278, while physics theory says that at that angle the friction value is 0.5774 (=tan(z)). And since the thoeretical values hold quite well for the Dynamic friction, we could use this table to bring both in line.

For instance, a smooth material with Dyn friction = 0.2 might have s Static value which is in nature a bit higher. in the table we can find that at say 15 degrees (value 0.2679) where we read that we should set the Poser Static friction to 0.04.

Same way, for skin and cloth Dynamic is about 0.7, and at 35 degrees we find that the equivalent Static is 0.2. But we can also see that at that point it rises quite sharp, so a slightly higher Static value might quite well be 0.5 or so. Which is the Poser default.

Hence, the Poser Dynamic friction does resemble real life good enough but the 0.1 default is far too low for skin and cloth. The Static friction does not resemble anything in real life to my current knowledge, but the default is not that bad for skin and cloth. But to stay in sync with smooth materials and quite lower Dynamic friction situations, Static is dropping to zero awfully fast.

= = =

Then I had a peek into Cloth Friction. I clothified the plank itself, put all its vertices in a choreographed group, combined both the plank and the former piece of cloth in one simulation and - of course - I checked the cloth-cloth collision box.

The first results were a nightmare, as the cloth started to wrinkle and crumble, and fell through the clothified plank. This was repaired by raising the fold-resistance (from 5 to 100).

Since then, I have not found any effect of varying this friction parameter on the position or speed of the cloth at any moment. the results are different from Static or Dynamic, but the same for all values of the Cloth friction.
On top of that, the great SM example page http://my.smithmicro.com/tutorials/2313.html does not show any differences between values 0.001 and 0.9, and notices that the effects will mainly be visible in animation. Well, not in mine!

So my question to you all: has anyone seen any noticeable effects in animation or stills of changes in this parameter? because if not, no investigation can be done. And then there is no need to, as any value will do for anything.

Besides all that, I noticed that the cloth and the plank always had a 2" distance after dropping / draping, whatever settings I used (especially for calculation offset and depth) wherever in the program.

Now back to the dungeons, focus on the stiffness parameters.

What would be so incredibly forward-thinking of Smith-Micro is to take this interesting, exhaustive study data, compile it into reference library of sorts, and then use this information for turning the interface into something designed less for physicists and more for the unwashed Poser artists... like me (well, I actually do wash, some... :biggrin:)

I'm glad you said what I was thinking...lol. All that physics stuff makes my eyes water...hehehe.

;o)

Laurie

LOL well I was going to ask politely if someone could translate for us that are mathmatically challenged...

What they should do, (which I know you can do by a script to load not save) is allow you to save setting presets just like you can save render setting presets and then re-use, share, etc.

Then the artist of the cloth could say use this t-shirt texture and load this cloth room settings or use the wool sweater texture and use my wool cloth room settings.

Or if you find certain settings that work on a given type of cloth, say leather, you can save it off as my leather and use on some other cloth very easily

You can already.

If I set up a simulation and do all my cloth settings before I save the clothing prop, those are saved with the prop. If I also gave my .dyn file that's created when you create a new sim, you could use that also. At least I think you can...lol.

edit: actually, you can't do the latter. I was thinking for some reason that you could load the .dyn file, but you can only create and delete.

But if someone gave all the other settings in say, the readme file, and the cloth settings are saved with the prop, it would be rather easy to set up.

Laurie

Quote - You can already.

If I set up a simulation and do all my cloth settings before I save the clothing prop, those are saved with the prop. If I also gave my .dyn file that's created when you create a new sim, you could use that also. At least I think you can...lol.

edit: actually, you can't do the latter. I was thinking for some reason that you could load the .dyn file, but you can only create and delete.

But if someone gave all the other settings in say, the readme file, and the cloth settings are saved with the prop, it would be rather easy to set up.

Laurie

Laurie, from what the wiser minds appear to be indicating, all those other settings are an essential part of any given item of clothing. You're a clothing designer (with a pretty awesome reputation, now, I might add )... you really don't want people mucking around with your recommended settings and then coming back with a "Please explain..." --- it's like, "hey, just follow the recipe and you'll be right"... right?

@Grichter

to be precise, when a clothified object is refined into object-groups (panel 3) and each dynamic group has got it's own parameters (panel 4), then these go with the object when being unclothified and clothified again (eg in another sim in the same scene), and also when being saved into the Poser library (! not in other saves and exports) for reuse in other scenes as well.

So one can (should?) indeed create a set of dynamic clothes, with all the belt loops and buttons in the right decorative groups, and with various dynamic groups each with their own parameters. So the leather not only looks like leather from the materials room but also behaves like leather in the cloth room. And of course users can change that, in materials as well as in behaviour. 

But while one can distribute new materials for a piece of clothes without the object, one cannot do that for cloth settings. This creates a copyright issue. But there exist some installer/zipper that requires the original file for input, what is it called? That might do a job on "dynamizing" existing clothes by the community without the rights violations.

@translation request

you're absolutely right, of course we do need an artist / popular / readable version of all of it.

But we need the physics too, and first, to ensure the story itself makes sense in detail and can be checked upon by others. Otherwise, the wrong results get translated. And I can't do both in one post or at the same evening, sorry for that.
But it will happen again :)

In the end, we want more grips on the details in panel 4. How do these settings effect our results, and what can / should we do to improve on them. From the various ways of accomplishing this
 - wild guessing
 - lots of trial and error
 - thinking virtual cloth sim algorithms
 - thing real world cloth behaviour
my personal strength is in the last one. 

Until now we've found that gravity, density, air-damping and wind force do relate very well to our Earthy real world, as long as kg, mtr and sec are converted to grams, cm and frames. This is not an academic observation, it's quite relevant for those who want to mix simulated cloth and animated objects in one short. It's also relevant for those who like to use existing (Wikipedia) material values for parameter input.

To wrap up:

gravity acceleration in Poser is 9,8 m/s2 ( = 9,8 * 100 / (30*30) ) = 1,089 cm/frame^2. It is slightly different from the one used in the Gravity script from the Scripts menu, so take care when mixing results from both.

density in Poser is gram/cm2, so the default 0,0050 means 50 grams/m2, about half the value for office paper and good for light linen. The max 1.0 means 10 kg/m2 which is about a sheet of lead of 1 mm thick.

air damping in Poser is gram/cm2 per second (not per frame!). An object that feels a force will accelerate, the airdamping will increase with velocity, and this results in a maximum speed for the cloth relative to the wind/atmosphere. So when out figure is wearing a gown, and some body parts are moving at about or above this speed limit, we can expect the cloth sim to break or to show that the other forces have to work hard to make it possible.

For a force of 1G (gravity) this speed is v = d.g/a for the Poser dial values d (density) and a (air damping). So our default light linen reads: v = 0,005 * 9.8 / 0,02 =  2,45 m/s (= 2,45*100/30) = 8,16 cm/frame. Which is not that much, and does have considerable effects on the speed of our animations, and the amount of frames needed to establish a decent simulation result.

windforce amplitude in Poser is m/s, that is: amplitude 1 applied horizontally to a cloth of default material (light linen) pulled down vertically by gravity, will bring the cloth into a 45 degrees angle. That is: 3,46 m/s. For amplitudes below 1 the dial behaves in a linear way, so 0.5 implies half the windspeed. For windspeeds above 1, doubling the dial value quadruples the windspeed. This translates into: 

 - amplitude 1,0 is the upper limit of Beaufort 2, light breeze. 
 - amplitude 0,5 is the upper limit of Beaufort 1, light air 
 - amplitude 0,1 is the upper limit of Beaufort 0, calm 
 - amplitude 2,0 is the upper limit of Beaufort 6, strong breeze
 - amplitude 3,0 is the lower limit of Beaufort 12, hurricane

Relevant for those who want to combine poses, moves, cloth sims and falling props into one believable shot. For instance: at windforce 2, the wind speed is 3,46 * 4 = 13,84 m/s. At default air damping, this will exercise a force of 13,84 / 2,45 (see above) = 5,65 G's on the cloth. This requires a figure working very hard to walk slowly forward against the wind, and also requires large stretch resistance values to prevent the gown from being ripped in pieces.

So I do hope that some understanding not only enables you to make believable dynamic clothes, but also to make believable dynamic pictures.

(to be continued...)

Attached Link: V4 falling on sofa

I made an animation of V4 trown on a sofa using Poser psysics. She's wearing dynamic clothing. To keep the lower part of the dress from folding on itself, I created a separate dynamic group to which I assigned more fold resistance and less shear and stretch resistance.

                                              UPPER PART          LOWER PART

Fold resistance                             5                           50

Shear resistance                           50                         15

Stretch resistance                         50                         15

Stretch damping                            .1                            .1

Cloth density                                 .05                         .05

Self-friction                                     0                           0

Static friction                                   .5                            .5

Dynamic friction                              .1                           .02

Air damping                                    .02                          .2

I left the additional cloth collisions to the default.

I think LaurieA is right. To be proficient in he cloth room, you have to be persistent. Keep practicing until you master it.

@argus1000

shot looks good. When you raise the stretch damping you will reduce the up/down bouncing effect of the skirt as well.

"... I left the additional cloth collisions to the default" - then, is there some typo in the last two parameters? Air damping 0.2 is for wind tight jackets or so, and Dynamic friction 0.02 is for lubricated teflon or alike :)

Practicing is one. And there is nothing as practical as a good theory. There is no single way out, and everyone in this thread contributes in a way that fits best. Thank you for that, please keep sharing.