How to simulate a falling sheet of paper?

[Phil_Boy]

I would use cloth for paper.
Just read some of the maya help files on creating cloth.
Then when youre a bit more familiar, select your cloth object and see its attributes.
And the crank up the air damping...

Sincerely,
Phil

[roxa]

MayaCloth is good, but it requires triangle faces on poly objects.

so, I prefer the softbody. it's good

[preeya]

hi
well i did the same thing few months b4
i've taken a single particle and added fields for gettig behaviour of paper falling,den i added a paper geometry as instance on particle object n also i've given some lattice animation on the orginal paper geometry for getting secondary motion on change in shape of paper as like a softbody .
i hope it helps .................

[jbradley]

I worked on a recent project where we had to match live action movement with a whole bunch of cg falling pieces of paper (photos actually), including hero photos.

As a couple of other suggested, softbody dynamics will be your best option. I played with everything - including using hair curves with dynamics to drive a softbound piece of paper and a 'spider joint system' (basically a set of bones radiating from the center of the paper). A support individual from alias even suggested using two dynamic hair curves lofted together - way way cool technique but I didn't have enough time with the deadline to really dive into that approach (but it has a LOT of promise).

Softbodies gave me the best results in the least amount of time. Unfortunately, it's extremely tricky with softbodies because they do not keep their original shape unless you jack up the goal weight attributes (or paint it pretty tight).

Here are some settings I used. Create a Nurbs plane, convert it to a softbody, add springs. Make the original Nurb plane a rigid body. I added fields to the rigid body as well to give it momentum and to calculate inter-photo collision in the scene. All other dynamics were handed by fields on the softbody.

For the springs:

Stiffness: 3.47
Damping: .2
Rest Length: 0
End1 Weight: 1
End2 Weight: 1

For the softbody particles:

Dynamics Weight: 1
Conserve: 1
Goal Smoothness: 2
Goal for nurb plane: .8
Goal Active checked

Add a few fields and give it a test. Note that for your fields, you will need to decrease the intensity for the softbody spring mass to keep its shape without getting out of wack. I used gravity, radial and turbulence fields with a maximum intensity of about 2, distance of effect to around 10 or so (for a piece of paper that was about scaleX: 8, scaleZ:10). Don't put the field too close to the softbody.

After you do your dynamics, you can bake out the particle animation. I also found that you can export the geometry at separate steps in the dynamic simulation, then import them into a new file (the geometry will have been deformed) and use blend shapes and keyframe animation to trick it out. Works very nicely if the scene is going to be quick or not right in your face.

Realistically mimicing a piece of paper falling is one of the hardest physics challenges today. A supercomputer at U of Ohio (I believe) was recently used to calculate the dynamics of paper falling ... what a complex physical situation that is. Wow.

good luck.

[Laeng]

1) The movement of the air.
2) The internal movement of the paper (bending...)
3) The movement of the paper in the scene.

For part1, you must be crazy to look for a realistic approach. You would need compressible flow calculations, and they are realy heavy. If you are interested in that topic, take a look at http://www.cfd-online.com/
What you to just take kind of a pattern that comes out at the end of a calculation.

Assume you already have something like 2:
the changing surface will affect the sourrounding air, resulting in a change of 3. So while your paper bends and folds, it will change direction, often with kind of a sudden change.

Try to create some air or wind fields, and connect their strength to the bending of the paper (with an Expression). You could do this by reading the normal at some surface points.
If the normal points towards an air field, it´s affected, if not, it weakens.

If you can´t read the normal, take 3 points A,B,C on the surface, calculate AB AC, and use this to get an orthogonal vector which will be your normal.

Or U just take something like a smooth noise funktion (one that changes slowly, and not randomly)

[joie]

WOW, what a bunch of responses...

The common problem of all of these questions is that I´m not dynamics or maths friendly, that´s the other guy here, the engineer.

Since he can´t do it because of the time available, I think I´m gonna rotoscpoe it, just thru my sheet of paper and film it, then animate it.

Cheers!

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