Motion blur is interpolating future frames?

[Phil_RA]

I made a scene with a few lights of which I animated the positions. For some reason, the motion blur makes it look as if it's done backward: the streak of light is not ending at the position where the light currently is in the frame, it's ending at the position of a future frame.



The red line shows the position of the light at that frame, and it's supposed to move down-left in the future frames (frame 35), yet the streak has already gone in that direction on frame 30. How is this possible? This is true for all the lights, on frame 30 they are where they would be on frame 35.

[gueoct]

I wonder, why nobody is answering here....
I suppose quite a few people use MoBlur, but nobody has noticed this issue?

we can see it clearly on those pictures from Mr. Kevin Shane he posted in "Gallery" some time ago.
Those cars look like they are going backwards!!!

We all know a similar issue in real-world photography while using flashlight:
When shooting a car passing by at night, with a long epxosure + flashlight,
the motion-blurred lights would be in front of the car instead of behind the car.
Modern cameras compensate for that by triggering the flash right before the shutter is closing .

[profbetis]

If the camera is following the car, there should be no motion blur. If this is what you're expecting and not seeing, you might need to enable "Object motion blur" on the car object, or even "Vertex motion blur" if there's some vertex deformation happening (but probably not)

[gueoct]

Of course we want motion blur. That´s what it is about.
The point is: the result looks like the car is going backwards!
The lights are sticking out in front of the car; that´s what Phil_RA meant with "...MB is interpolating future frames...", right?

[stratified]

In Octane you can configure the position of the shutter interval relative to the current frame. Options are After, Before, Symmetric. This is how it's done in the standalone but you should be able to configure it in MAX.

cheers,
Thomas

[gueoct]

i do not think so.
Has anybody found this feature?

[Obizzz]

I've noticed some issues when the shutter speed is longer than the actual animation. Maybe this is caused by something like this?

[JimStar]

3ds Max plugin doesn't have the opportunity to choose a motion blur direction (it is "after" by default in Octane engine).
I'm working on adding all the missing things to this plugin, so I will add this feature too in later versions.

[jamestmather]

Has this been addressed? I too have crazy long motion blur. I imagine you set it to 1/50 or 1/48th instead of 1 in the render settings/camera panel? Or is it controlled from the camera?

[paride4331]

Hi jamestmather,
https://docs.otoy.com/3DSMaxH/3DSMaxPlu ... ion%20blur
Regards
Paride