Hi all,

I am a student just about to begin my masters project in Digital Effects at Bournemouth uni. I have decided I would like to try and demolish a building, similar to the animation on the start page of the Houdini help. Does anyone know if there is any articles about the effects sequence shown in the help in Houdini or how it was done? I am assuming DOPs/POPs but some more info would be a great help as a starting point.
Thanks very much.

Dean.

I can tell you in general terms what's going on there.

The building was modeled as a pre-broken set of pieces, which were taken into DOPs and blown up. The dynamic simulation itself is pretty straightforward, but I know a lot of tweaking and rerendering went on to get the pieces to do nice things as they bounced around. Also I think this was all done before DOPs was officially released, so some things were probably harder to set up or control than they would be now.

The glass blowing out is a particle system, and the dust cloud is another particle system, rendered as, um, dust.

Then the whole thing was composited together.

I know when you break something apart in dynamics it usually has to be pre-fractured, but would you model the whole building whole and then break it into the pieces using some sort of poly tool (booleans or just poly split?). Also how do you know how to break it up so it will disintergrate realistically?

would you model the whole building whole and then break it into the pieces using some sort of poly tool (booleans or just poly split?)

The few examples I saw involving “destroying” things, the model was pre-broken using the Cookie SOP. (Booleans).

Also as a starting point, have a look at the DOP_examples contained in the DOP_rbdGlueObject operator. There is a breaking rock and a Shattered glass.

Hi

I have started doing some simple tests for blowing up my building. I am simply trying to blow up a prefractured brick wall. Something I hadn't considered is how to actually simulate the force of the explosion affecting the wall! I tried animating the scale of a sphere rapidly, and using that as an RBD object next to the RBDfractured object of the wall, but as soon as the sphere expands to come in contact with the wall the pieces it intersects dissapear as opposed to being blown away.

Do I have to slow the speed of the expansion or do I need to tweak accuracy settings in my solver?

the problem with expanding a sphere in sops is that when dops reads in the geometry it has a hard time reading a velocity on the object. This is important for the solver to accurately figure out what the object is actually doing.

The building explosion was done with a block hitting from the inside. The animation of the “destructor” was done w/ dops, i.e. giving it a velocity in Z. This allowed the RBD solver to calculate not only the point of impact, but also the force of the impact.

hope this helps,
-j

I've messed about with that approach and its not going to be feasible. I asked my project tutor and he had a look and came to the same conclusion. He has suggested using a POP_DOP to simulate the force of the explosion, with the POP net consisting of simply a location POP spraying particles in all directions for only one or two frames. He sent me a demo hip file which seemed to work well, so I may go that route.

I did some tests with a sphere from SOPS and giving it some velocity in DOPs, worked fine but with an explosion force is expelled in a 360 degree manner so I think the POP route may be a good solution. What are your thoughts?

Thanks for your input guys.