jim c Posted August 7, 2011 Share Posted August 7, 2011 I have a scene where for some reason the motion blur is not working. I've got a still I'm trying to render and I'd like motion blur on. I have a piece of geometry that's rotating. The rotation is happening at the SOP level (as opposed to modifying the transforms at the Object level). In the mantra node I've got motion blur turned on, xform and geo samples at 10, and pix samples at 5. Everything else is at the default. I have the current frame set to near the end of the last key frame, so it's clear that the rotation is taking place. Yet when I render there's no motion blur present. If I make a simple little scene with geo shape and a similar setup the motion blur works fine. Any ideas what I'm doing wrong? Quote Link to comment Share on other sites More sharing options...
ehsan parizi Posted August 7, 2011 Share Posted August 7, 2011 I have a scene where for some reason the motion blur is not working. I've got a still I'm trying to render and I'd like motion blur on. I have a piece of geometry that's rotating. The rotation is happening at the SOP level (as opposed to modifying the transforms at the Object level). In the mantra node I've got motion blur turned on, xform and geo samples at 10, and pix samples at 5. Everything else is at the default. I have the current frame set to near the end of the last key frame, so it's clear that the rotation is taking place. Yet when I render there's no motion blur present. If I make a simple little scene with geo shape and a similar setup the motion blur works fine. Any ideas what I'm doing wrong? Make sure you have V attribute in your sop level(add a trail node and set it to compute velocity if needed) + try turning on your "Geometry Velocity Blur" under the Sampling tab of Render tab in your geometry in OBJ level. Quote Link to comment Share on other sites More sharing options...
jim c Posted August 7, 2011 Author Share Posted August 7, 2011 OK that sort of works. It at least introduces the motion blur. But it's not quite what I'm after. Attached is my render (on the left) and what I'd like it to look a little more like (on the right). The problem is that the yellow parts give impression that they are not moving at all. Scrub the timeline and you can see them move. If it matters I'm using the TransformAxis SOP to perform the rotation. Quote Link to comment Share on other sites More sharing options...
ehsan parizi Posted August 7, 2011 Share Posted August 7, 2011 your attached render doesn't seem having any kind of motion blur, or it's very subtle, is that the new one?! anyway, if you upload a simple version of your file, maybe I can help more then! btw, I don't think that transform axis sop is causing the problem, but I've never used it myself. Is there any advantage in using that instead of xform? Quote Link to comment Share on other sites More sharing options...
ehsan parizi Posted August 7, 2011 Share Posted August 7, 2011 is that motion blur happening in reflection?! Quote Link to comment Share on other sites More sharing options...
jim c Posted August 7, 2011 Author Share Posted August 7, 2011 Yep, the image on the left is my render with your suggested changes. Prior to that NOTHING came out. I'm sure there's something silly that I'm doing wrong I just don't know what it is yet. Yeah I tried to make a simple test case. And I can't duplicate the problem there It all works fine. I need to use transform axis over the xform SOP because the modeled geometry is at a bit of a weird angle (it's not aligned on the world XYZ axis), so the regular xfrm just makes it wobble all over. Quote Link to comment Share on other sites More sharing options...
jim c Posted August 7, 2011 Author Share Posted August 7, 2011 is that motion blur happening in reflection?! The is a glass material that's in front of the rotating parts. Would that be a problem? Quote Link to comment Share on other sites More sharing options...
jim c Posted August 7, 2011 Author Share Posted August 7, 2011 It's the glass! I'll be damned - it's doing something that prevents the motion blur from being visible. Quote Link to comment Share on other sites More sharing options...
ehsan parizi Posted August 7, 2011 Share Posted August 7, 2011 Yep, the image on the left is my render with your suggested changes. Prior to that NOTHING came out. I'm sure there's something silly that I'm doing wrong I just don't know what it is yet. Yeah I tried to make a simple test case. And I can't duplicate the problem there It all works fine. I need to use transform axis over the xform SOP because the modeled geometry is at a bit of a weird angle (it's not aligned on the world XYZ axis), so the regular xfrm just makes it wobble all over. ok, what if you use $CEX, $CEY and $CEZ for your pivot in transform node?! I think that way you can get rid of that weird rotation problem. but anyway, if the duplicated scene file works fine, why don't you copy all of your nodes to that and use that file?! one more thing, what kind of rendering engine are you using?PBR? or micropolygon? Quote Link to comment Share on other sites More sharing options...
anim Posted August 7, 2011 Share Posted August 7, 2011 you can turn on Raytrace Motion Blur on mantra node or add that property to your object or use raytrace or PBR engine to render your scene Quote Link to comment Share on other sites More sharing options...
ehsan parizi Posted August 7, 2011 Share Posted August 7, 2011 (edited) It's the glass! I'll be damned - it's doing something that prevents the motion blur from being visible. So if it's that, you can simply use Mantra Surface Shader and change the settings to get the glass look! Edited August 7, 2011 by ehsan parizi Quote Link to comment Share on other sites More sharing options...
ehsan parizi Posted August 7, 2011 Share Posted August 7, 2011 you can turn on Raytrace Motion Blur on mantra node or add that property to your object or use raytrace or PBR engine to render your scene Hey Tomas, I remember the raytrace in houdini didn't work very well, I mean it was super slow, am I wrong? although I haven't used it for more than a year, so maybe in H11 it's working fine! Quote Link to comment Share on other sites More sharing options...
anim Posted August 7, 2011 Share Posted August 7, 2011 it really depends on many factors, but if you are raytracing or instancing something, then it may be faster, but raytrace PBR in 11 is even faster than raytrace(from my experience) so I rarely use raytrace mode now Quote Link to comment Share on other sites More sharing options...
jim c Posted August 8, 2011 Author Share Posted August 8, 2011 (edited) Weird. It seems like any glass/transparent material that I put in front of it will block the motion blur *unless* I render with PBR. If it matters I'm using H10, though I'm hoping to upgrade to H12 as soon as they release it. PBR looks great, but takes forever once you crank the samples up. Edited August 8, 2011 by jim c Quote Link to comment Share on other sites More sharing options...
jim c Posted August 8, 2011 Author Share Posted August 8, 2011 Is it possible to export the motion blur info as an image plane and then apply it in post? Quote Link to comment Share on other sites More sharing options...
anim Posted August 8, 2011 Share Posted August 8, 2011 in h11 PBR is much faster than in h10 have you tried raytrace? Quote Link to comment Share on other sites More sharing options...
jim c Posted August 8, 2011 Author Share Posted August 8, 2011 Just tried it. Yeah it works OK, but it seems even slower than PBR. Quote Link to comment Share on other sites More sharing options...
jim c Posted August 8, 2011 Author Share Posted August 8, 2011 Just tried adding the Enable Ray-Traced Motion Blur property. Toggling it on or off makes no different for a micropoly render. So is this behavior a bug or just the nature of the micropoly renderer? Quote Link to comment Share on other sites More sharing options...
anim Posted August 8, 2011 Share Posted August 8, 2011 Is it possible to export the motion blur info as an image plane and then apply it in post? I am not sure image plane will work through raytracing either, I haven't tried however there is one on exchange http://www.sidefx.com/exchange/info.php?fileid=608&versionid=608 but what you can do is render MB with micropolygon without glass then cameramap resulting image/sequence onto all geometry except glass as a simple constant material then render with micropolygon with the glass on or maybe try PBR in H11 or soon 12 Quote Link to comment Share on other sites More sharing options...
anim Posted August 8, 2011 Share Posted August 8, 2011 Just tried adding the Enable Ray-Traced Motion Blur property. Toggling it on or off makes no different for a micropoly render. So is this behavior a bug or just the nature of the micropoly renderer? it's difficult to tell it works in H11 for micropoly behind refraction Quote Link to comment Share on other sites More sharing options...
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