watchman Posted February 14, 2012 Share Posted February 14, 2012 (edited) Hello everyone, I have written out tons of geometry to disc to use them for collisions with fluid in DOPs, but by mistake I set my IsooffsetSOP to save IsoSurfaces instead of SDFVolumes. I saw here and elsewhere people saying that SDFs should be saved out for collisions but since it took me whole night to save these IsoSurfaces I wonder if I have to re-save them again as SDFVolumes? What is the difference? Can I use IsoSurfaces instead of SDFVolumes? They look pretty much the same in DOPs. Thank you Edited February 14, 2012 by watchman Quote Link to comment Share on other sites More sharing options...
rafaelfs Posted February 14, 2012 Share Posted February 14, 2012 (edited) Hello everyone, I have written out tons of geometry to disc to use them for collisions with fluid in DOPs, but by mistake I set my IsooffsetSOP to save IsoSurfaces instead of SDFVolumes. I saw here and elsewhere people saying that SDFs should be saved out for collisions but since it took me whole night to save these IsoSurfaces I wonder if I have to re-save them again as SDFVolumes? What is the difference? Can I use IsoSurfaces instead of SDFVolumes? They look pretty much the same in DOPs. Isosurface is polygonal geometry, while SDF is a field. They're quite different and the only reason they seem the same in DOPs is because when you check "show collision geo" in DOPs it'll create an isosurface out of your SDF for visualization purpose only. It's much easier to evaluate the collision SDF if it's shown as polygonal geometry than as a field... SDF (signed distance field) is a field that stores at each voxel the distance to the closest point on the surface and a sign that tells if you're outside or inside the surface. It's much faster to calculate collision with SDF than shooting random rays from a point in space and collecting the distance to closest surfaces at each frame. So YES, you'll have to re-save the SDFs, cause the isosurface is of no use to calculate volume based collision. That's the sad part. Is there a specific reason why you're generating the collision SDF prior to simulating? Since the RBD object DOP will generate it on the fly on frame 1 anyway... Edited February 14, 2012 by rafaelfs Quote Link to comment Share on other sites More sharing options...
watchman Posted February 14, 2012 Author Share Posted February 14, 2012 I need to find the best parameters for my sim and since the hard surface animation with deforming geometry is 100% done I thought it might be a good idea to bake collision surfaces and be more creative with my sim later. But thank you anyway I will rerender the SDFs. Quote Link to comment Share on other sites More sharing options...
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