How can i fix the vector motion blur problem?(see video)
i dont want to use the sampled motion blur because it takes too much render time
Video:
Any chance of seeing the node setup as a screeny? It’s hard to tell what may be going wrong (if it is). Remember that vector blur is a fake, when pushed to extremes it may not work the way you expect.
Perhaps you will have to render the frames oversized to allow extra image for the coordinate space to generate position data. Then crop that stuff out after the bur.
I did a quick test and found that you need to provide more faces for position or velocity information. To fix it I added a “simple” subdivision modifier to all the geometry. This increases the first pass render and may affect your models too. But it gives the blur node more data to estimate a blur especially close to the edge of frame.
I have had the same issue when doing projection mapping of photos for photogrametry.
The ground of that scene is a very long plane with one face,i that gonna effect the blur?
Yes it will. My test also had long faces. I suggest that you apply heavy subdivision.
I would suspect that least part of the problem here … of why it seems to be that the bottom plane is really “goin’ funky on ya,” has in part to do with 3D-to-2D geometry.
Let me try to illustrate my idea (and I don’t entirely know if it is right!) by asking you to visualize a long isosceles triangle: the short vertical leg, closest to you, represents the screen plane. The lower leg, extending a long way in the distance but at a slight upward slope, represents the ground, and we don’t care about the third leg. Got that? Okay, now, turn the triangle sideways in your mind so that you can look at it from the side as I proceed.
Now, in 3D space, we know that there’s a strong negative motion-vector (coming at you) along the ground plane. Little balls rolling down the hill or something. That’s the 3D vector. But, from the point-of-view of the screen-plane leg, what does that motion look like? Trace horizontal lines and watch it: lots and lots of short vertical streaks. And they’re all taking place in a very small area. That could very easily wind up as a distortion of some kind, and it would look worst-of-all exactly where it does: in a small region of the screen-plane that is being asked to present a “big” motion that is visually compressed into that very “small” space. It might even produce enough distance between one frame and the next that the sense of continuous motion is disrupted, ergo, “the jitters.”
What if you try this? “Just blur it.” Defocus it. Given that you’re rushing headlong anyway, maybe a very slight amount of vector-less blurring will get the job done.
