hatrick Posted May 7, 2009 Share Posted May 7, 2009 hey, i m wondering how to get propper motionblur of objects copyed on a particle system...i tried to ad velocity with a point sop a.s.o but i m not geting goot results i also played around with the motionfactor settings in my outputmantra without success thx Quote Link to comment Share on other sites More sharing options...
Ezz Posted May 7, 2009 Share Posted May 7, 2009 hey, i m wondering how to get propper motionblur of objects copyed on a particle system...i tried to ad velocity with a point sop a.s.o but i m not geting goot results i also played around with the motionfactor settings in my outputmantra without success thx You can use the TrailSOP for this. Erik Quote Link to comment Share on other sites More sharing options...
dbukovec Posted May 7, 2009 Share Posted May 7, 2009 You have to check "Use template point attributes" on the copy node, to get the velocity for your copies Quote Link to comment Share on other sites More sharing options...
SpencerL Posted May 7, 2009 Share Posted May 7, 2009 You can use the TrailSOP for this.Erik Actually, you cant use the trail SOP in this situation if the point count is changing per frame as it calculates "v" based on the point number. Quote Link to comment Share on other sites More sharing options...
Ezz Posted May 7, 2009 Share Posted May 7, 2009 Actually, you cant use the trail SOP in this situation if the point count is changing per frame as it calculates "v" based on the point number. Ahh Im sorry if a caused confusion here. Well I guess in some cases you can use the trailSOP. Erik Quote Link to comment Share on other sites More sharing options...
Jason Posted May 7, 2009 Share Posted May 7, 2009 You have to check "Use template point attributes" on the copy node, to get the velocity for your copies On top of this, you must get "Velocity Attribute Motion Blur" on the Object's rendering properties (under the Geometry tab) Quote Link to comment Share on other sites More sharing options...
xoctan657 Posted May 12, 2009 Share Posted May 12, 2009 Actually, you cant use the trail SOP in this situation if the point count is changing per frame as it calculates "v" based on the point number. that is nice so i cant use the trail sop to compute velocity if the number of geometry's point will changed within time . Quote Link to comment Share on other sites More sharing options...
SpencerL Posted May 13, 2009 Share Posted May 13, 2009 that is nice so i cant use the trail sop to compute velocity if the number of geometry's point will changed within time . correct. Velocity is calculated by subtracting the previous frames velocity of each point. If points are generated or die over time, then the point numbers change and therefore it wont be calculating the correct point as its looking at the previous frames point number. Quote Link to comment Share on other sites More sharing options...
Netvudu Posted May 13, 2009 Share Posted May 13, 2009 mrrrmm...so there is no actual way to import a particle system and have its motion blur properly calculated unless the imported particles have the velocity info embedded? Quote Link to comment Share on other sites More sharing options...
Owl Posted May 13, 2009 Share Posted May 13, 2009 well i guess you can always use particle id instead of point number to calculate velocity Quote Link to comment Share on other sites More sharing options...
anakin78z Posted May 13, 2009 Share Posted May 13, 2009 Keep in mind that velocity blur will never give you 'proper' blur anyhow, since it's always the velocity from the previous frame to the current, while all other blur in houdini (by default anyway, now you can change it) blurs from the current frame towards the next. Most of the time you won't notice, but since you asked.... Someone at some facility wrote a node that calculated velocity based on the ID attribute, rather than point number, so changing point counts didn't matter. Also, it looked at the next frame, rather than the previous to compute proper velocities. Maybe this is something Sesi could implement at some point. Another caveat is rotations however, which don't get blurred. If you have a fast spinning object on a particle and use velocity motion blur, you're only going to get blur from the translation, not the rotation. Just keep that in mind. Quote Link to comment Share on other sites More sharing options...
hatrick Posted May 13, 2009 Author Share Posted May 13, 2009 thx guys lot of info here... Quote Link to comment Share on other sites More sharing options...
edward Posted May 14, 2009 Share Posted May 14, 2009 Another caveat is rotations however, which don't get blurred. If you have a fast spinning object on a particle and use velocity motion blur, you're only going to get blur from the translation, not the rotation. Just keep that in mind. But that's why you can now have multiple Geo Time Samples now in Mantra. Quote Link to comment Share on other sites More sharing options...
stevenong Posted May 14, 2009 Share Posted May 14, 2009 Yes, we have Geo Time Samples now but with geometry copied to particles, it won't work so we're back to Velocity blur. Cheers! steven Quote Link to comment Share on other sites More sharing options...
anakin78z Posted May 14, 2009 Share Posted May 14, 2009 exactly... Now if someone were to implement angular velocity blur... o:-) Quote Link to comment Share on other sites More sharing options...
edward Posted May 14, 2009 Share Posted May 14, 2009 Yes, we have Geo Time Samples now but with geometry copied to particles, it won't work so we're back to Velocity blur. Ah yes, when I came back to this old thread, I assumed one would just use render time instancing. Quote Link to comment Share on other sites More sharing options...
anakin78z Posted May 14, 2009 Share Posted May 14, 2009 But... that also doesn't work? Unless I'm missing something, even when using instancing, you don't get rotational blur... in fact, I'm not convinced that multiple time samples work with velocity motion blur at all. Now, if you don't have changing point counts, you can set Point Motion Blur to Compute sub-frame geometry (deformation), which WILL work, but we've already established that we have changing point counts.... -z Quote Link to comment Share on other sites More sharing options...
edward Posted May 15, 2009 Share Posted May 15, 2009 If you're instancing, and your instances aren't changing point counts from frame to frame, then deformation blur should work, no? Quote Link to comment Share on other sites More sharing options...
Netvudu Posted May 15, 2009 Share Posted May 15, 2009 and your instances aren't changing point counts from frame to frame, Obviously, Edward was reading a different thread for several days, and all of sudden started posting at this one Quote Link to comment Share on other sites More sharing options...
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