Here, I've recreated the problem in the simplest possible setup, no weird rotation order and it's centered on the null, just draw a region to see the problem.
File: http://www.stopp.se/arvid/motionblurbug.scn Different rotation speeds of the ball yield different arcs though, so sometimes you'd get lucky to hit a number that doesn't show the problem, which is why the problem appear at random for us. The problem was solved by skinning the geo to the null instead of parenting it, which invokes deformation motion blur, but the scene gets more complex and the rig gets heavier. Please see if I've missed something in my settings, I'd love to solve the problem without skinning! Cheers On Tue, Jul 17, 2012 at 6:09 PM, Manny Papamanos < manny.papama...@autodesk.com> wrote: > I did a quick test and the blur seemed to look good in MR on a simple > cube spinning on a moving cube hierarchy. > Be sure you don't use 'offset' in the MB settings or the wheels or they > may look like they are coming out of the wheel wells. > Check the transforms on your 'centers' on the wheels and all the parents > for weirdness. > If something weird is based on the parents, one way out of this is to plot > and then use that motion on the wheels. > Also, perhaps playing with the 'rotation order' may help, I would make > sure that the spinning axis is first on the list. > > > -manny|SI support > > > From: softimage-boun...@listproc.autodesk.com [mailto: > softimage-boun...@listproc.autodesk.com] On Behalf Of Arvid Björn > Sent: Tuesday, July 17, 2012 10:20 AM > To: softimage@listproc.autodesk.com > Subject: Re: Car wheel motion blur > > Thanks, I tried your suggestion, but there's nothing wrong with the > parenting. It is related to parenting, but that's not where the problem > lies. It works fine with deformation motion blur with the exact same center > of rotation, so that proves that the problem is in how transformation > motion blur is being evaluated. When evaluated per point with a global > vector, everything's fine. I wish I could force MR to do that even though > I'm not actually deforming anything. > > > On Tue, Jul 17, 2012 at 1:56 PM, Alok Gandhi <alok.gandhi2...@gmail.com > <mailto:alok.gandhi2...@gmail.com>> wrote: > Most probably the motion samples are creating an arc due to parenting. > What you need to do is to check this is take the fcurves and scale them > quite a bit. This will allows you to see in "slo-mo" the trajectory of the > wheel as it moves along. If you see the undesired arcing then I would > suggest changing the parenting so the center of motion is at the center of > the wheels. > >
