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Simulating a falling tree

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I just saw a VFX breakdown on Avengers at Weta's website. They show the simulation of a falling tree as a playblast.

Here's the video


its the last of the four clips.

It would be pretty cool if someone could give me a basic idea, on how you would simulate something like this in houdini?

I especially mean the bouncing of the branches?

Thanks in advance,


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check out the L-System SOP and the wire object

you can make a tree with the L-System - that is make of curves - then make those curves into wire objects that you can sim in DOPs

check the help cards

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thanks michael.

I took a look at the wire object and the L-System trees. Now I have a few more questions.

The final tree I want to simulate ist not a conifier with one big major trunk and many thin (wire-like) branches.

I'm aiming for something like this....


To get it right...would this be a good way to go for??

I would try to make a RBD simulation for the Major trunk and some thick branches. Cause I want the main/thick Wood to splinter and break. I constrain the curves of the fine/mid branches to the rbd simulation, so i get nice bending for them. Then I would deform my BranchGeometry with the dynammic wires?

I know its a big Topic but I need the basic idea, to be able to work it out for myself...

thanks in advance

Edited by LouisXIV

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I think you're on the right track...

build your truck and major branches in geometry

sim them for motion and break up (splinter and break)

write this out

read it back in

populate them with wires (curves) to represent your mid/fine branches

make these curves wire objects

sim them

use them too build branches and/or use the resulting simmed wires with the wire capture/deform to deform pre-built branches

start very small with many simple tests, break up everything into small parts that you can get a good workflow for

and post here whenever you need some help and try to include simple hip files so we can see what you're doing

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Yeah, Michael laid it out pretty well. Basically there are two main ways to animate stuff with simulated wires:

1) after DOPs massagging you use them to deform your complex geometry with wire capture/wire deform. This wire deformer is the usual method you would use in most 3d packages.

2) after DOPs massagging you use them to model the branches from this curves. This method is way more procedural (i.e. smart and flexible) and Houdini-exclusive, but depending on the model, pipelines issues might prevent you from using this method.

Edited by Netvudu

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Thanks for your answers. :)

Now I got the basic idea. As Michael recommended, i'll start with small test and post them here.

And more detaild Questions and Problems, wich I'll have for sure ;-)

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Hi! I know this is an old thead but I have a question related to this.

I'm looking at the wire defromer but it does not seem to want to take a point attribute into the radius of the influence enveloppes.

I have an attribute 'thickness'->$THICKNESS on my wire and I want to use this to adjust each influence envellope so that the thin branches have small envelopes and the larger parts have larger envelopes?

Is it possible to do this with the wire deformer?

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