kingsoz Posted July 12, 2005 Share Posted July 12, 2005 Hi 3D people, I have been trying for ages and ages to get motion blur to render with geometry copied to particles but it simple has no affect at all! If no geometry is copied to the particles and the default spheres are used on the particle SOP then this does work with motion blur, but i really do need the geometry copied to them. I have tried all 3 motion blur types and altered the shutter speed enless times but they have no affect! If anybody has any idea how to solve this it would be much appreciated Thankyouuuuuuuuuuu King Soz Quote Link to comment Share on other sites More sharing options...
pushpathadam Posted July 13, 2005 Share Posted July 13, 2005 Hi, the short answer: you need to add velocity attributes after your copy sop. ie use a point sop, add velocity, multiply the velocity for an added effect... ex $VX*8 etc the longer answer which I'm paraphrasing from the help docs, Rendering/Troubleshooting_Mantra_rendering/is that for mantra's motion blur to work the number of points/cv's has to be consistent from frame to frame. With a template particle system your point count changes as the sim progresses. I would check that you are inheriting the particle velocities, at the copy sop (last tab ..inherit point attributes), use a point sop for adding velocity. Another Gotcha. Test it with a new mantra rop and lock all the motion blur parameters...(camera, object, and rop) to velocity attribute. The default mantra render tab seems to have motion blur off. cheers Tom Hi 3D people,I have been trying for ages and ages to get motion blur to render with geometry copied to particles but it simple has no affect at all! If no geometry is copied to the particles and the default spheres are used on the particle SOP then this does work with motion blur, but i really do need the geometry copied to them. I have tried all 3 motion blur types and altered the shutter speed enless times but they have no affect! If anybody has any idea how to solve this it would be much appreciated Thankyouuuuuuuuuuu King Soz 19453[/snapback] Quote Link to comment Share on other sites More sharing options...
kingsoz Posted July 13, 2005 Author Share Posted July 13, 2005 coool thanks, i'll give it a go and let u know if this works! thanks Quote Link to comment Share on other sites More sharing options...
kingsoz Posted July 13, 2005 Author Share Posted July 13, 2005 hey man, it didn't work! i added the point SOP to the end of the copy SOP and added velocity, multiplied them by 8, put velocity attribute motion blur on in the output and still nothing! am i doing it wrong?? sorry to keep bothering you King Soz Quote Link to comment Share on other sites More sharing options...
kingsoz Posted July 13, 2005 Author Share Posted July 13, 2005 fixed it!!! you don't have to do anything complicated with point SOPS, just on the copy SOP under the attribute tab turn on 'copy template point attributes'!! and thats it thanks for the hints tho! King Soz Quote Link to comment Share on other sites More sharing options...
DaJuice Posted July 13, 2005 Share Posted July 13, 2005 The Trail SOP can also compute velocity for you. Quote Link to comment Share on other sites More sharing options...
old school Posted July 14, 2005 Share Posted July 14, 2005 The Trail SOP can also compute velocity for you. 19483[/snapback] But then you are full circle and stuck with broken motion blur the moment you add in another particle-object to the system. Yes the Trail SOP can not calculate velocity between two sets of geometry that are not the same as does Mantra and PRMan. Stick to velocity-based blur. Velocity motion blur isn't the panacea that it seems to be. You have to tweak the amount of the velocity vectors to get the blur to match real motion blur. For this use a Point SOP after the Copy SOP and go to the Particle folder. Turn on Use Velocity and then multply the $VX, $VY and $VZ variables to get the blur right. I usually multiply each variable by 0.5 as a start to simulate a half-frame shutter speed then tweak from there . Another issue is that the geometry-object may be scaled in the Object network or in other words, "in a different space". You have to account for this with respect to the velocity vectors. Remember that the velocity coming out of POPs is just that: the current instantaneous velocity of the particle. Hopefully this is something reperesenting the distance the object has travelled from the previous frame to the current but not always. If a particle encounters a strong force, well, your velocity may not be quite right. It is for this reason that in some cases I build my own velocity vectors which is the actual distance the particle has travelled from the previous frame to the current frame in POPs or SOPs. Just things to watch for when using velocity based blur. Quote Link to comment Share on other sites More sharing options...
Bernard Posted July 14, 2005 Share Posted July 14, 2005 Hi 3D people,I have been trying for ages and ages to get motion blur to render with geometry copied to particles but it simple has no affect at all! If no geometry is copied to the particles and the default spheres are used on the particle SOP then this does work with motion blur, but i really do need the geometry copied to them. I have tried all 3 motion blur types and altered the shutter speed enless times but they have no affect! If anybody has any idea how to solve this it would be much appreciated Thankyouuuuuuuuuuu King Soz 19453[/snapback] Hello, Where can you set those 3 motion blur types? I searched , but didn't find... many thanks, bernard Quote Link to comment Share on other sites More sharing options...
TheUsualAlex Posted July 14, 2005 Share Posted July 14, 2005 Hello,Where can you set those 3 motion blur types? I searched , but didn't find... many thanks, bernard 19513[/snapback] Howdy, They are: Transformation Blur, which works with SOP level animation Deformation Blur, which works with Object level animation Velocity Blur, which takes on velocity point attribute to determine the motion blur. You can find them on your Object's render tab or your ROPs. Velocity Blur is pretty nice because you can actually just sholve your own velocity vector into any point and do your own motion blur. However, as stated earlier, generally you'd want to use velocity blur when dealing with particle animations. HTH, Alex 1 Quote Link to comment Share on other sites More sharing options...
DaJuice Posted July 14, 2005 Share Posted July 14, 2005 Thanks old school, I wasn't aware of all that stuff. Good to know. Quote Link to comment Share on other sites More sharing options...
i-d Posted February 19, 2008 Share Posted February 19, 2008 Well, here is an old thread with a wealth of information on some fresh issues regarding of course motion blur on copy objects, particles and instances. One of the first things what a new houdini user diggs out is a beautiful motion blur that mantra has and wishes to use it almost on everything, cant get enough of the good stuff, even rendering really, really slow animations with enormous motion blur, heh, that looks even more groovey O.K. for a Houdini 9.1 things are little more different, more user friendly, or more lottery like compared to H8. In H9 you should get your motion blur by only checking it in render settings, high shutter for camera and there you go, but we can get into problems. As I found out with simple copy SOP spheres on animated revolve surface, no motion blur whatsoever, because I was having sin$F expression instead of sin$FF for curve point that makes revolved surface basic my dear Watson you say, but as a beginner its a good excercise to grasp difference between floating and hole numbers as houdini sees it. I didnt see any difference until I restared scene, thats maybe one thing to look for. ye old school post is great help Quote Link to comment Share on other sites More sharing options...
Sagroth Posted July 27, 2008 Share Posted July 27, 2008 old school mentioned building your own velocity vectors to correct mblur issues from strong forces (I'm having "ladders" instead of smooth trails). How can that be done? Quote Link to comment Share on other sites More sharing options...
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