I always had troubles when I wanted to use vector blur in blender
I now wonder if the problem come me
So this is what i have
The result and the result give by blender with the motion blur node
Witch basicaly mean the blur is going in both direction
like this
The result shouldn’t be something like this
you should make some part disappear on one side and get longer on the other side but not get longer on both side…
I wonder if I am clear enough.
cause it’s really annoying when you have curve direction and collision.
Well Is it a Bug or i have just some trouble to understand physic??
It’s not a bug. That’s the correct behaviour. Remember that motion blur is due to exposure time. Both the pixels in the “front” and in the “back” get less time on a given object in the time that passes from one frame to the next.
I’m surprised by this, it indeed seems to be correct behavior for motion blur. To be sure I tested it with full sample motion blur in Blender and with motion blur enabled in After Effects. Best way to test something like this is with a real camera of course.
My intuition about how motion blur works is similar to Yoyo’s example.
That’s probably because you’ve been seeing that incorrect behavior in games so often. It’s easier to implement that way. And on real films you didn’t pay much attention.
The difference between 2 effects like this is hardly noticeable in moving images like film and games unless your looking for it and freeze frame the picture. Most of the time motion blur is more subtle, you only notice its there when its not, like in 3D.
The reason why I initially believed the motion blur behavior Yoyo illustrated was correct was logic, not observation. If I was to manually ad motion blur to a photograph in photoshop I would just blur the “rear end”.
Another source of the mis-impression is probably comix, 2D cartoon animation, and some kinds of illustration where “speed lines” are used to show rapid action, always trailing the object in motion. It kind of gets equated with motion blur but it’s a graphically different effect.
I believe your confusion is partly justified. Blenders vector blur is not ideal, it sorta blurs into the future. The downsides of that are visible when an object comes into the view or an object accelerates/decelerates.
It also has it’s problems with fast moving objects but considering that it almost costs no rendertime, it’s acceptable.
yoyo (and zordan) the blur before an object is from the shutter opening, the blur ahead of teh object is from the movement as the shutter closes. This mimics what you’ll see taking real photos or film.
Some software allows you to create stylised blur by allowing the virtual shutter to open slow and close instantly or to sample positions over several frames… this isn’t possible in the real world and can look pretty strange.
don’t forget that vector blur in blender is reliant on vertices so to get good looking effects you may need to subdivide your geometry
and also you can use the brute force of sampled motionblur (perhaps with fewer passes than will work woth this method alone) and vector blur together which can increase the accuracy and maintain some speed…
