Realistic Motion Blur settings to match film

[cum. m+d]

Hey guys,

There are too many settings available in Maya Vray for me to truly get what is the correct settings for a film like motion blur.
I adjusted my exposure to match what I read as typical shutter speed for film which is 1/50 of a second.

Duration (frames) - I tried 2 but I read somewhere else that says 0.5 looks more real.
how many samples would be realistic. Could you kindly advice me on every one of these fields?

I have a helicopter and I want it to look as good as it can be.

https://www.screencast.com/t/zF6BvT2vdnc

[sharktacos]

Be aware that many of the parameters for MB in the Render Settings are disabled when MB is on for a physical camera. I think duration is disabled (I may be wrong, this is from memory). You should set your camera to "film camera" which will lock down your shutter speed. If you disable exposure, you don't need to worry about that and just get the motion blur. Then it's really just a matter of having the correct number of rotations per second. Helicopters are about 460-600 rpm. So if we say 500rpm that's ~8.5 rotations per second (500/60=8.5), so 3060 degrees (360*8.5) every 24 frames.

You will also need lots of geo samples to capture that per frame. I see from your pic you have 6 samples per frame. You'll need waaaaaaaay more.

[dgruwier]

Read this, which explains shutter angles (film cameras) and their relationship to shutter speed (digital cameras):
http://neiloseman.com/?p=4221


Then check out this chart from the Arnold user guide:


Shutter angle here is the same as the frame duration in VRay. So a 180 degree shutter is the same as 0.5 duration, which means that for each frame, the motion blur spans half a frame of motion.

Stick with 0.5 unless you have something specific you're going and know what you're doing. If you need longer motion blur on your helicopter blades, I'd suggest making them go faster instead of increasing the motion blur. 2 duration doesn't make sense in video, as it'd mean motion blur that overlapped between frames, but it would make sense if you're doing long-exposure style stills.

If you're using a physical camera and don't use the override, then it's the shutter speed that controls the length of the motion blur (I think). In that case, you'll need a 1/48 shutter speed at 24fps or 1/50 shutter speed at 25fps to match the 180 degree shutter angle, as per the link I posted before. I just always use the camera override and set the duration unless I need to match settings with a real camera.

[Morbid Angel]

There are a few things you need to do before getting correct motion blur, especially in cases like helicopter. First and the most important is your rotor blade and any other 3d geometry must be moving either exactly the same or very close to realistic scenario, i.e. like the real rotation of the helicopter rotor. You have to know the model number of your heli how many rpms its rotors do, then match it 1 to 1 in 3d. They have some really crazy rpms so this is important to getting the correct motion blur. The second step is understanding the geometry samples. In 3d, we are limited by many factors so a lot of things are biased or clipped down to make performance gains. Such is the geometry sample in 3d motion blur is set to 2, meaning start and end position of the object on given frame. However, a heli rotor rotates so fast it does multiple subframe positions. So you have to set the geo samples to something like 6 in order to get proper rotor rotation motion blur.

Usually setting the rotor geometry to have custom geo subframe samples and leaving the rest of geo at 2 is a good way of working. The other thing is the shutter settings.

You want to set it to duration 0.5 (180 deg shutter) and interval center at 0.0 (start of frame).

[rikou]

Then check out this chart from the Arnold user guide:
[ATTACH=CONFIG]36695[/ATTACH]

Can't read this chart
can you post it ?

Thanks

[sharktacos]

of course you can also sync the frame rate of the camera to match the rotors and get this sorcery...

[dgruwier]

Can't read this chart
can you post it ?

Thanks

Sorry, something must have happened with the attachment.
You can find it on the bottom here, along with more info:
https://support.solidangle.com/displ...UG/Motion+Blur

[rikou]

Sorry, something must have happened with the attachment.
You can find it on the bottom here, along with more info:
https://support.solidangle.com/displ...UG/Motion+Blur

Thanks you