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  1. #1
    Join Date
    May 2006

    Mantra Motion Blur Offset problem

    Hi there,

    I'm doing my first render tests in Houdini Mantra. I'm testing the motion blur settings on some Rigid body dynamics and found that if Shutter Offset is at 0, my scene doesn't render with motion blur. If I have it at -1 or 1 there are some blur results, but I want the motion blur to happen around the current frame without any offset.

    My motion factor I've kept at 0.5 but if I ramp it to something like 10, it still doesn't render the Motion Blur.
    Xform and Geo samples are at 2.

    Would anybody know why this is the case or if I'm missing something?

    "What is any life without a dream to pursue?"

  2. #2
    Join Date
    Nov 2013
    Have a look at inbetween frames on the time line, if you're not seeing a smooth interpolation that will explain the issue.
    The xform time samples will only apply to motion blur to object level keyframed animated object so if your doing any animation in sops level this will make no difference and should be set to 0.

    Motion factor is a quality slider, putting this higher reduced quality of your shading.

    The reason you are seeing motion blur when you have your shutter offset at -1 and 1 is because you have geometry cached at intiger frames, so. For example if your current frame is 4 and shutter offset is at 0, you will need a difference in the geometry at frame 3.5 and 4.5 in order to see motion blur. Since you probably have geometry at intiger frames when shutter offset is at -1 or 1 houdnini is blurring between frames 3 and 4 for example.

    If your rendering the live geometry in your scene just drop down the timeblend SOP and houdini will do a liniear blend at non intiger values which will give you what you need for your blur to work.

    If you want to render from a cache (usually good for keeping your IFDs small, more production friendly), you just need to cache with 0.5 intervales so you get inbetweenf frame geometry.

    If you have consistant topology/ point numbers you can ensure that you will get inbetween frame vl

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