Physical Camera Movie mode Mblur.

[Metzger]

What does Physical camera in movie mode default to?

When not using Physical camera, a interval center of 0, by a frame of .5 is always pretty money.

The shutter angle of 180 when changed doesn't effect the motion blur at all.

Mixing renders with motion blur are becoming a pain when using Physical camera in movie mode. We can't match filmed motion blur with the physical camera. The only Vray setting that matches is interval 0, by frame of .5 with non physical camera.

Thanks

-Scott

Using stable build under linux.

[Metzger]

When in Movie mode, the camera doesn't calulate anything past a shutter of 90. The default 180 does nothing. 90 and 180 are currently the same.

[snivlem]

So it doesn't affect anything when past 90?

[Metzger]

Yep. 90 and 180 are the same.

[Zdravko]

We add this issue in our "to do" list.

[vlado]

It will work fine if you set the motion blur settings in the camera rollout to 0.0/0.5 for the interval center/duration (looks like our exporter only looks at these values to determine time samples for the scene; will fix this), and you also need shutter offset to -90 and shutter angle to 180. Currently from the UI you can't set the shutter offset below 0 - will fix this too, but you can also edit the attributes.txt file in the vray/scripts folder to set the bounds for the parameter or you can do it with a python post-translate callback.

Best regards,
Vlado

[Metzger]

How does editting the attributes.txt work when rendering on the farm? Is that local, or will it carry? I don't know if edditing the txt file will work with our setup.

[vlado]

Would be best to get the lates stable build - I just sent you an email.

Best regards,
Vlado

[Metzger]

Great.. interval center at 0, duration .5 180 shutter angle on physical camera with a shutter offset of -90 works.

Now my question is this.

A. In the future, will we have to set the camera duration and interval center in the globals, along with adjusting the physical camera? That is really a serious hassle to have to adjust motion blur settings in both areas. If I use Physical Camera DOF, I don't expect to dial in another set of settings in the render globals. The V-Ray defaults should be interval center 0 with a duration of .5. If we have to dial the globals now, along with the physical camera motion blur settings, then can we get those interval center and duration to show up right under the enable motion blur check, along with having them grey out if they are turned off?

B. The Offset having to be set at -90, is that a actually a bug then? The Physical camera should be 180 with an offset of 0. Will that also be fixed?

I really appreciate the fast fix for that, but I think correcting it fully instead of having a strange workaround would be more appropriate for future builds. Thanks!

So just to clear this up. And for any future reference.. If you want to match motion blur using a physical camera to a plate shot on film you have to do this:

Open V-Ray render globals.
Under the V-Ray tab for Camera turn motion blur on.
Set Duration to .5.
Set Interval Center to 0.
Turn Motion blur off.

Grab your camera, add Physical Camera.
Set your Camera type to Motion camera.
Set Shutter Offset to -90.
Enable Motion blur.

Then go to your scene prefs and make sure you are set to 24fps. (Does this still matter? I think there should be an override in the physical camera for motion camera FPS.)

Thanks again Vlado and everyone else at ChaosGroup!!

[Metzger]

Hmmmm... Something is causing the renders to be a lot brighter now with the new version, and render times are twice as long.. Also I just noticed the Focus distance is causing the image to get darker or brighter based on the distance setting. Even if DOF is turned off. I'm gonna look into the render time taking longer..

[vlado]

A. In the future, will we have to set the camera duration and interval center in the globals, along with adjusting the physical camera?

No, of course; like I said, this will be fixed.

B. The Offset having to be set at -90, is that a actually a bug then? The Physical camera should be 180 with an offset of 0. Will that also be fixed?

Nope, it is not a bug, so nothing to fix. The shutter offset just controls when the film is opened for exposition relative to the Maya frames in the timeline.

Then go to your scene prefs and make sure you are set to 24fps. (Does this still matter? I think there should be an override in the physical camera for motion camera FPS.)

It does matter. The FPS determine the time during which the film is exposed, so this affects exposure (if the film is exposed for 1 frame, this means a different time interval for 30fps and 25fps).

Best regards,
Vlado