Long shutter motionblur, only trail behind, not infront?

[hermit.crab]

fixeighted kosso_olli Thank you for your feedback. Excuse the lack of direct answers, however, your replies were considered. Regarding the issue, the "future sampling" so to speak is due to the interval center parameter, which you can modify above the -1/1 UI limitations via MaxScript. In kosso_olli's scene, setting a positive bias and a negative interval center (i.e. -50 for a duration of 100f) should produce the desired effect. The MaxScript to control the interval center's value is:

renderers.current.moblur_intervalCenter=-50

Buck A similar setup on your setup should produce your desired result. However, in Maya, it's a tad more complicated since the interval center is locked as a value (I'll talk to the devs to make it take custom values). There is a workaround, which is exporting a .vrscene and rendering through the Standalone application. To export a custom interval center value you may either edit the "interval_center" line in the exported .vrscene or use the following post-translate python script for a direct edit of the .vrscene through Maya and afterward render with Standalone:

from vray.utils import *

smb = findByType('SettingsMotionBlur')[0]
smb.set('interval_center', -50)

EDIT: I've logged an improvement request (internal bug-tracker id: VMAYA-10017) to remove the value limitation of the interval center parameter.

[fixeighted]

I'm not sure I understand.
If, as is shown, by using the video cam with latency plus shutter efficiency, it works as required, why is having to use maxscript either preferred or better or different?

[kosso_olli]

I'm not sure I understand.
If, as is shown, by using the video cam with latency plus shutter efficiency, it works as required, why is having to use maxscript either preferred or better or different?

Seems the maxscript command is a workaround for now. If the render settings accept values other than -1/1, I would prefer not to use the video camera, as it has other limitations.

fixeighted kosso_olli Thank you for your feedback. Excuse the lack of direct answers, however, your replies were considered. Regarding the issue, the "future sampling" so to speak is due to the interval center parameter, which you can modify above the -1/1 UI limitations via MaxScript. In kosso_olli's scene, setting a positive bias and a negative interval center (i.e. -50 for a duration of 100f) should produce the desired effect. The MaxScript to control the interval center's value is:

renderers.current.moblur_intervalCenter=-50

Well, thanks. But did you also consider the "bias" value? In the scenes provided there was no way to make them work. While your solution might work regarding the general blur, there is no option to control the fading towards the start of the frame. The video camera on the other hand does this.

[fixeighted]

[QUOTE=kosso_olli;n1091419]

Seems the maxscript command is a workaround for now. If the render settings accept values other than -1/1, I would prefer not to use the video camera, as it has other limitations.

Of course, good point I haven't tried this yet but will see how it works later.

[hermit.crab]

Well, thanks. But did you also consider the "bias" value? In the scenes provided there was no way to make them work. While your solution might work regarding the general blur, there is no option to control the fading towards the start of the frame. The video camera on the other hand does this.

The bias parameter seems to work fine on your scene. I've already mentioned that it has no effect on physical cameras (only free/target cameras or perspective views). See attached images (frame 100, motion blur duration 100f, interval center -50, bias 0/10).

[kosso_olli]

I've already mentioned that it has no effect on physical cameras (only free/target cameras or perspective views).

Well, thanks. But what would really help immensely is if that information was in the docs. If it was there, we would not have to fiddle around with settings only to find out that they are not supported by the current camera. The docs really need some love.

[fixeighted]

Can I ask why it is necessary to hide the functionality which works in this case - i.e. the interval?
Many other parameters for many things exceed any logical multiplier, making those just guesswork (without explanation anywhere) - so why just the occasional one here and there is confusing, to my mind.
I realise it's impossible to cover any and all eventualities but this interval one appears obviously usable above/below the current constraints.
Maybe there was a good reason...

Maybe it is possible to have a check box which would allow those who wish to, to exceed the default where it is feasible and won't break stuff; like the existing global ability to either leave at default or switch to advanced settings.

[hermit.crab]

kosso_olli It already is.
fixeighted I guess it wasn't designed for this type of scenario. As already mentioned, I've already logged an improvement request to allow arbitrary values in the interval center parameter.

[fixeighted]

Thanks. It is very useful as an effect - pretty widely done also, though previously hardware intensive.
So I guess the more things improve the better e.g. Vray will be in handling what would otherwise and previously have been done in post or with fakey 2D Max plugins.
All good

[Buck]

EDIT: I've logged an improvement request (internal bug-tracker id: VMAYA-10017) to remove the value limitation of the interval center parameter.

Thanks Aleksandar, much appreciated