Ocean Interaction with static objects

[phong]

Hi!

I'm currently trying to get objects interact with an HOT ocean. I used the hot ocean_displace and inserted some box geometry into the ocean. As you can see in the image attached, the ocean works fairly good for itself, but at the transition lines between ocean and dummy objects there's some kind of reaction missing. This is what I'm most curious about. What would your approach be to get something like foam or wave reflections, or what else is missing around these boxes? Since I used the precompiled ocean_displace I can hardly change the displacement's behavior.

Kind regards,

Phong

Edited August 4, 2009 by phong

[CodeBreak]

This is a very good question. I actually wondered this myself until I watch a behind the scenes uber-short of "Making of The Day After Tomorrow" water effect.

Digital Domain (I believe it was them) had the base water mesh that didn't really do any dynamic interactions with objects, expect for maybe moving around the buildings and being the bulk of the mass. They then created a 2nd water pass that handled all of the particle and dynamic effects that happened where the water was supposed to interact with a surface or object. They were then, of course, composited really well so they looked like one cohesive dynamic surface.

So, unless you can find a way to do this using dynamics (ie: making both a rigid body, but give the ocean a gravity of 0 in a separate node maybe?), I'd say do it like the studios and cheat. It's all the same after post.

NOTE: I'm currently trying to see if I can do it with dynamics alone. I'll update you if I find anything out.

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UPDATE_5:36am_Aug_28th_2009

I got a sphere object to interact with the deforming ocean mesh surface by making the sphere an RBD Object, and making the Ocean a Terrain object. I then went into the AutoDopNetwork, selected the ocean referenced geometry and checked the option "Use Deforming Geometry". This causes the RBD Sphere object to move with the Ocean surface's wave patterns.

Now I'm trying to figure out how to have the RBD Sphere surface interact with and make wakes in the Ocean surface as it's tumbled around. I know that no matter what the object is, it breaks the surface of water and is submerged to a degree.

Does anyone out there know of a way to make the mass of the ball displace the already displacing surface of the ocean, submerge itself a bit, and make wakes? This can be done easily within Maya with a couple clicks in the Dynamics menu, but I haven't the foggiest how to do this kind of high level interaction from within Houdini and would love to know how also.

Edited August 28, 2009 by CodeBreak

[Marc]

Making the ball displace the ocean isn't going to be easy. It's probably possible to do by bringing the sphere into SOPs and using it's shape to affect the ocean, but since the HOT just affects the points and isn't in itself a simulation, there's nothing you can do as part of the simming process to make it react.

What you could do is use the ripple solver to bring the ocean in and have it react with the rbd object, but that's probably not going to affect your waves in the way that you expect. However since the ripple solver is just propagating waves through a mesh then it's possible that it amounts to pretty much the same thing anyway . It'll need a lot of tweaking though.

What I would do is use the ripple solver and then on top of that use a cookie to get the intersection and generate a particle sim for little splashy elements to put over the wave and the ripples.

M

[CodeBreak]

What I would do is use the ripple solver and then on top of that use a cookie to get the intersection and generate a particle sim for little splashy elements to put over the wave and the ripples.

M

Whoa...ok....lol. If I upload a starting scene, do you think you can template what you're talking about? And does it matter what version (x86/x64) it was made? That's if you use Windows of course.

[Macha]

I don't know the inside workings of HOT but I tried something similar with xsi ICE last year. I measured the distance between wave and object used it as a weight to change the phase and amplitude, etc.

It worked OK for shorelines and objects where you can simply use a raycast. The waves will refract around object. If the object moves you get a trail as well.