Covering objects, removing the cloth covers, and playing with the wind.
Cloth Room without Clothes.

Download this tutorial in PDF format (1.7 Mb).
Download a set of Bagginsbill’s cloth squares (X-tris only).

Introduction and Preparation

In this Case Study I’ll present some basics from Poser Cloth Room. I’m going to use pieces of cloth to cover objects, and to use as flags and banners. I also will introduce some animation, like moving objects, waving flags and using wind.

To save you the time finding or making decent pieces of cloth, I’ve included some in the package that also contains this PDF. Credits to BagginsBill who presents a far larger package for study purposes on his own site

http://sites.google.com/site/bagginsbill/free-stuff

To start, I’ll open Poser, delete the default figure (select it and click [Del]), and ensure I’ve got a ground plane and some light. Then I add an object to the scene, say a car.

To add a piece of cloth, I can just open the (Windows) Explorer, pick the piece I like and drag it into the scene. I like the 3m sized cloth with a 20mm resolution, which contains (300cm/2cm)² = 22,500 vertices. When you experience performance issues on your machine, you can take a smaller cloth with a lower resolution (as the 2m cloth at 40mm contains (200/4)² = 2500 vertices, a tenfold less. Which of course will give you coarser folds and wrinkles.

I scale the cloth to 250% to ensure it can cover the car properly, and I give it a blocked texture to reveal to folds and wrinkles.

 

 

I put the cloth somewhat above the car, I’m done with preparations, and enter Cloth Room.

In Cloth Room, I create a [New Simulation…] (panel 1), give it a meaningful name and accept all other default values.

With the cloth selected, I click [Clothify…] (panel 2) to define the cloth object,

and I click [Collide Against…] to define the collision objects.

I use [Add/Remove…] and check Car and Ground, accept with [OK]

and continue with [OK] to accept all other default values. Now I [Calculate Simulation] (panel 4).

I see the cloth fall onto the car (the message tells that while calculating frame 8, the previous one took about 0.6 sec), and I can start to analyze this first result. Save your file.

From the first result I see that the cloth needs more time to settle, and in [Simulation Settings…] (panel 1) I extend the 30 frames (1 sec) to 90. And I [Calculate Simulation] again.

Now I see the car poking through (some red spots), and I do have my doubts about the quality of the folds.

So I adjust the [Simulation Settings…] another time. By checking the first (Object vertex…) option – always the first step in improvements, by checking the third (Self-collision) option to prevent the cloth to fold into itself, and I double she Steps per Frame from 2 to 4 to refine the calculations. That’s fine, I did not need the 2^nd option. The more options I check the more time it takes to complete a proper simulation. The collision options don’t need a change at all. Let’s peek behind the [Collide Against…]. The little triangle lets me choose between the collision objects Figure (aka the Car) and Ground. The Offset reads 1, that is: the cloth will remain 1 cm from the car. The Depth needs attention only when the cloth and car are moving rapidly towards each other which might introduce artifacts (not the case now), Friction is meaningful when cloth and car slide along each other, and the options are meaningless as the car is not a character, and hence has no ‘zero pose’ nor a head, hands or feet. Save your file.

The 1 cm offset represents quite a thick kind of cloth, while the folds and crumbles on the ground are quite fine. Actually, I like a bolder impression of the material. Actually, Poser default cloth represents fine silk, which is known for high air damping (it gently floats down) and for low resistance values (silk folds very well). So, for my bolder impression, I increase the resistances and reduce the air damping, and I take serious steps doing so to get the noticeable results.

	Default	My settings
Fold Resistance	5	50 or 500
Shear / Stretch Resistance	50	250
Stretch Damping	0.01	0.1
Air damping	0.02	0.002

The first thing I notice is that the entire cloth folds onto the ground at about frame 20, much earlier as in the first run. This is due to the reduced air damping: the cloth floats less and falls faster.

Second, the “look and feel” of the cloth is mainly determined by the Fold Resistance parameter. Here you can see it raised from 5 to 50 (left) and then to 500 (right). The latter is the real heavy stuff.

Now, select the cloth as well as the latest frame in the simulation range

Click menu Object > Spawn Morph Target (give the result a decent name, like “Cloth over Car”)

 

 

 

Followed by menu Figure > Create Full Body Morph (you can use “Cloth over Car” again)

 

 

The first step defines the shape of the cloth as a morph target, the second creates a Morph Dial in the cloth properties (Pose Room):

 

 

 

To see the effect of this, [Clear Simulation] in Cloth Room, go back to simulation / time frame 1, change to Pose Room and change the Morph dial from 0 (flat cloth floating above the car) to 1 (cloth neatly folded as resulted from the simulation). We’ve frozen the sim results. Save your file.

Now I’m going to have fun with some animation. First, in Pose Room, I set the time slider to frame 1, and hide the cloth (properties, check Visible OFF). Then I select the car, move the slider to frame 30 and I move the car 6 to 7 meters in Z direction. I don’t care about rolling the wheels, that’s for later refinement when I’m up to it. Back to frame 1, and I unhide the cloth again.

After ensuring that the Cloth over Car morph dial is set to 1, I switch to Cloth Room and click [Edit Choreographed Group…] in panel 3. This opens the Group Editor, and I pick a few vertices from the cloth. The editor can be closed with the (red crossed) close button in the upper right corner.

The vertices we’ve just selected will be excluded from the cloth sim calculations, but will follow the preset movements of the cloth itself. If the cloth was animated like the car, those vertices would follow that animation (hence the name: choreographed). At the moment however I’ve not animated the cloth, and therefore the vertices in the Choreographed group will stay put while the car drives forward, underneath the cloth. I only have to [Calculate Simulation…] to make it happen. And wait a while, as most frames seem to take about 10 sec each, and I’ve got 90 of them (that makes say 15 mins, depending on your computer speed).

To view the result properly I’ve got to switch to Pose Room and set the Cloth over Car morph to 0. At frame 30 the result is like:

And that one spot seems glued to the ground.

So the cloth stretches a lot and then contracts while slipping off the car. I also see the Fold Resistance is 50.
So I set Fold Resistance to 500 to make the thick cloth with the fat folds, and I raise Stretch Resistance to 900. Another way is to reduce the Friction parameters to make the cloth slide easier over the car. I [Clear Simulation], I ensure that the Cloth over car morph reads 1 again, and I [Calculate Simulation…] again. When done, I set Cloth over Car morph to 0 (Pose Room), select frame 20 as it shows a fun result and render. This is it:

and you see that the cloth stretches far less, and sort of jumps from the car. When you want, you can enhance the scene by putting a pylon, or a high heeled girl, right onto the glued spot as if that object or figure is nailing the cloth down while the car drives away.
By using menu Object > Spawn Morph Target and menu Figure > Create Full Body Morph at say frame 90 you can freeze the sim result again.

As freezing some vertices in the cloth is quite an artificial way to create a result, the question is: what’s the alternative? What happens when I just put a heave object upon the cloth? Let’s find out.

First, I clear the groups in the cloth by [Edit Choreographed Group…] and clicking [Remove All]. This empties the group, and all vertices will join the simulation again.

Then (from Pose Room) I put a small (cylinder) object upon the cloth

Second, back to Cloth Room, I add this object to the set of collision objects, using the [Collide Against] (panel 2). In that same window, I select (using the small triangle) this object, and I set both Friction parameters to their maximum: 1.0. Then I select Ground, and I do the same.
I leave the car to its defaults.

Third, I give myself the proper start position with [Clear Simulation] and by setting the proper Morph dial to 1.

And, in the cloth properties panel, I check the Collision Friction option. This tells the simulator NOT to use the values below from the cloth object, but to use the values from the collision objects instead. And that means that the clot will experience extreme frictions from ground and pylon object, and default friction from the car.

[Calculate Simulation…] does the job again, and viewing the proper result might require to set the Morph dial to 0 afterwards (Pose Room, frame 1).

 

My result looks like this:

Not too bad. Actually the frictions for the car a somewhat high so the cloth gets pulled forward even at the extreme frictions between the cloth and the car and ground. Frictions apparently do not stop all sorts of movement.

Frankly, the 0.1 dynamic friction is quite high for cloth sliding over a well lacquered steel car roof anyway, and so is the static friction of 0.5. Both can be lowered at our liking, but when doing so it has to be done in the Collision Objects collection as the sim uses that info instead of the friction from the cloth parameters.