I am trying to do quite a complex ambeint occulsion render. It is taking forever, a friend of mine has suggested I use the clip SOP to clip any geometry outside of the camera view (the scene is a building exploding so a lot of geometry goes out of the camera view as it blows outwards) thus speeding up the AO render. I've looked in the help, and it does indeed say you can use the clipSOP to do this, but then it fails to say how! I looked at the example HIP files but they didn't explain how to clip anything outside the camera view. Could someone explain to me how this is done?
I am trying to do quite a complex ambeint occulsion render. It is taking forever, a friend of mine has suggested I use the clip SOP to clip any geometry outside of the camera view (the scene is a building exploding so a lot of geometry goes out of the camera view as it blows outwards) thus speeding up the AO render. I've looked in the help, and it does indeed say you can use the clipSOP to do this, but then it fails to say how! I looked at the example HIP files but they didn't explain how to clip anything outside the camera view. Could someone explain to me how this is done?
Sorry if I'm being dense………
I haven't tried frustum culling with a clip SOP. The way I traditionally do it is by projecting UVs using a UVTexture SOP, then deleting every prim that's completely inside or outside the view, depending on need, etc., and wrap the whole thing into an OTL, as this won't be the last time you'll use this technique!
Just be careful - you can clip all you like, but if you're doing occlusion, be aware that data will be popping on and off all over the place. I've fairly sure it would give you serious flickering.
As a rule, when I do occlusion, I don't delete data mid-animation unless I'm really, really sure. I think you'll need a process far less drastic than just what's in the cam view.
Depending on how you are doing your occlusion and your type of scene you might be able to limit the distance that the shader checks for occlusion this can very dramatically speed up the calculation.
The trick is finding just the right hammer for every screw
