athomas Posted October 2, 2003 Share Posted October 2, 2003 I've got 10000 spheres copied to particles with very high velocity (5000 along y), when I try to render with motion blur using velocity blur everything comes to standstill, using 2gigs of ram and swapping to disk and still at first bucket after 2 hours. Now when I turn on transformation blur no blur at all, also when I animate my camera position I still get no motion blur. Anybody any tips on how to achieve a rendering with motion blur at acceptable times or how I can set up 'in camera blur'? Many thanks Andre PS. Can't change the sphere/pop setup and running Houdini 6.0 on Linux. Quote Link to comment Share on other sites More sharing options...
Jason Posted October 2, 2003 Share Posted October 2, 2003 Are they blurring through the camera? And what type of entities are they? Primitives/NURBS/polys? Quote Link to comment Share on other sites More sharing options...
athomas Posted October 3, 2003 Author Share Posted October 3, 2003 They are all nurbs spheres at random sizes. No they don't blur through the camera, but I like to achieve that without needing to go down the velocity route. Oh btw, I have to get the motion blur in the renderer for test purposes, so can't use comping for this. Quote Link to comment Share on other sites More sharing options...
Jason Posted October 3, 2003 Share Posted October 3, 2003 10,000 NURBS spheres with extreme motionblur near camera is going to choke any renderer! Yeah, you might be better off just using sprites. Can you do that? If it absolutely HAS to be 3d spheres, at least convert to poly's and push your camera "near" plane as far forward as can. You may have to down down your Micropoly Splits from 10 down to 4 or something. If you want a technical description of why this kind of thing is diificult, I can provide more info; but trust me - it's hard for a micropoly renderer to do. What is the shading of the spheres? i.e; Any raytracing going on? Quote Link to comment Share on other sites More sharing options...
athomas Posted October 3, 2003 Author Share Posted October 3, 2003 Thanks Jason, OK I've rendered the scene in prman at just under 2 hours, although only the camera is moving there from where I get my blur. Thats why I was wondering if I can do camera mblur in mantra. As for the shader actually very simple, a fractal noise giving me opacity and a random (very important this one) texturemap for every sphere, one light casting a filtered shadow. Because I used nurbs in prman I have to stick with it here, I'm trying to replicate the exact conditions to get a good comparison. Also I do would be very interested in the details why this is difficult. Cheers Andre Quote Link to comment Share on other sites More sharing options...
athomas Posted October 3, 2003 Author Share Posted October 3, 2003 PS. I just had a thought, do you think it would work if I animate my Geo at object level a little bit and then do transform blur, since I'm only interested in a single fram eright now? Quote Link to comment Share on other sites More sharing options...
stu Posted October 3, 2003 Share Posted October 3, 2003 Hi athomas, If you're using prman and the objects are moving quickly, turn the motion factor value up to 3 or 4 in the specific tab in the prman output driver. It automatically turns the samples down for drastically blurred objects seeing as they are so distorted anyway. I know that you've already said that you can't do this, but using primitive spheres would speed things up as well. stu Quote Link to comment Share on other sites More sharing options...
Jason Posted October 3, 2003 Share Posted October 3, 2003 Yeah, unfortunately mantra does not have a Motion Factor setting. I think half of the problem may be because you're also raytraced shadows. Did you raytrace shadows in PrMan? I would: *) switch to depthmap shadows *) or if you cant; -- *) switch to fastShadows if possible (these dont evalute the shader on the shadowing object) -- *) turn down the Raytraced LOD very far (maybe to 0.1) -- *) optionally switch off raytraced motionblur (in the + button, mantra fine quality control settings) Quote Link to comment Share on other sites More sharing options...
Wolfwood Posted October 4, 2003 Share Posted October 4, 2003 Hi athomas,If you're using prman and the objects are moving quickly, turn the motion factor value up to 3 or 4 in the specific tab in the prman output driver. It automatically turns the samples down for drastically blurred objects seeing as they are so distorted anyway. I know that you've already said that you can't do this, but using primitive spheres would speed things up as well. stu In addition to what stu said if you're using RenderMan Pro Server (11.5) you could try the new extreme motion blur setting. Which provides better sampling for VERY fast moving objects. jim. Quote Link to comment Share on other sites More sharing options...
stu Posted October 4, 2003 Share Posted October 4, 2003 You might try manually turning the shading rate down as well, especially if the spheres are blurred anyway. stu Quote Link to comment Share on other sites More sharing options...
Jason Posted October 4, 2003 Share Posted October 4, 2003 Very true! Quote Link to comment Share on other sites More sharing options...
athomas Posted October 5, 2003 Author Share Posted October 5, 2003 Thanks Guys for all your responses, but I feel I didn't explain properly. I have done the rendering in PRman already and it worked fine, took about 2 hours at 2k. I now want this to compare against mantra, so I'm trying to replicate the exact scene. It worked fine without mblur, but I'm unable to do the mblur with it. Cheers Andre Quote Link to comment Share on other sites More sharing options...
Jason Posted October 6, 2003 Share Posted October 6, 2003 Oh, I see; yeah.. I guess prman is more suited to that type of scene since it has good optimisations for extreme motionblur. You could get it rendering in mantra with a little bit of finessing, but perhaps this particular scene is pretty hard on mantra. In my experience, moving very close to a displaced object - say an ocean surface - renders much faster in mantra than it does in prman. I think massive blur will definately hurt mantra more though. Cheers, Jason Quote Link to comment Share on other sites More sharing options...
athomas Posted October 6, 2003 Author Share Posted October 6, 2003 Hey Jason, got it working now, using my method mentioned before animating at the obj level and doing transform blur. Unfortunately you have to animate the object to achieve this rather then just animating the camera as one would expect. I don't know if it is intentional or a bug. Cheers Andre Quote Link to comment Share on other sites More sharing options...
shikung444 Posted October 18, 2007 Share Posted October 18, 2007 I have a scene with the camera moving through a field of falling sprites. I have the sprites motion blurred from their own velocity, but the movement of the camera is not being taken into account for the motion blur. How do I tell the renderer to include the camera movement in the evaluation of the motion blur? Sorry for resurrecting an old thread but I searched and found this question still wasn't resolved. Hey Jason,got it working now, using my method mentioned before animating at the obj level and doing transform blur. Unfortunately you have to animate the object to achieve this rather then just animating the camera as one would expect. I don't know if it is intentional or a bug. Cheers Andre Quote Link to comment Share on other sites More sharing options...
stevenong Posted October 18, 2007 Share Posted October 18, 2007 I can't verify this now but a workaround is to compute the velocity of the camera then add (or subtract) it to the points. This will fake camera motion blur. Cheers! steven Quote Link to comment Share on other sites More sharing options...
crunch Posted October 18, 2007 Share Posted October 18, 2007 I have a scene with the camera moving through a field of falling sprites. I have the sprites motion blurred from their own velocity, but the movement of the camera is not being taken into account for the motion blur.How do I tell the renderer to include the camera movement in the evaluation of the motion blur? Sorry for resurrecting an old thread but I searched and found this question still wasn't resolved. Wow, a thread from 2003... There was a bug fixed in a very recent build of H9 that allowed camera motion to be picked up when rendering from the viewport menu. If you render from the output driver, you should be getting camera motion blur. And now, in very recent versions of H9, you should also get camera motion blur from the viewport menu (when looking through a camera). Is this what you were experiencing? Quote Link to comment Share on other sites More sharing options...
shikung444 Posted October 18, 2007 Share Posted October 18, 2007 I rendered a 30 frame sequence from the output driver rendering from a moving camera and only got velocity based motion blur on the sprites, that didn't take into account the camera motion. I just wanted to make sure there wasn't something obvious I was overlooking. I'll try to do some more tests/ experiments today. And thanks stevenong, for your suggestion. I thought of that also, but was hoping I wouldn't have to resort to that kind of workaround for this. Would you just use a point sop to add the velocity to the sprite points? And compute the camera's velocity with a trail sop? Wow, a thread from 2003...There was a bug fixed in a very recent build of H9 that allowed camera motion to be picked up when rendering from the viewport menu. If you render from the output driver, you should be getting camera motion blur. And now, in very recent versions of H9, you should also get camera motion blur from the viewport menu (when looking through a camera). Is this what you were experiencing? Quote Link to comment Share on other sites More sharing options...
shikung444 Posted October 18, 2007 Share Posted October 18, 2007 (edited) Attached is a 10 frame quicktime video explaining the problem. One of the objects is a geometry box. The others are all sprites. The discrepancy in motion blur from the camera motion is obvious here. Any suggestions? Edit: I tried stevenong's suggestion, and was able to use a single point and a trail sop to calculate the velocity of the camera, and use a point sop to add or subtract that velocity to affect the motion blur of the rendered sprites. However, I think the vector may need to be normalized or something ( my math knowledge is not very advanced), anyway the motion blur is not going in the direction of the camera. motionblurtest.mov Edited October 19, 2007 by shikung444 Quote Link to comment Share on other sites More sharing options...
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