Hello,

I am having motion blur problem.
We have obj and point cache from softimage for adding effects.
We use Arnold for softimage.
All passes are rendered with motion blur in softimage excrept effects.
Effects are all rendered with Mantra.
And problem is we need to match the motion blur settings as close as possible to use animated character as hold out but we can not get right settings…..

Arnold's motion blur settings are
Shutter start(open) : 0.25
Shutter end(close) : 0.75
centered frame

sorry but I am not sure about shutter angle setting…. ( I can check more on Monday)

Inside Houdini,
I tested with shutter time and motion blur style. but no luck so far….

I really appreciate it if some one has solved this kind of things and help me out. It helps me a lot even with Maya.

Thank you

SItoA:
Start: 0.25
End: 0.75
Duration: 1
Pos.: Center On Frame

Houdini:
Camera>Sampling>Shutter Time 0.5 (default)
Mantra>Sampling>MotionBlurStyle>Frame Centered Blur

That should match, does here anyway in a little test. If your geometry is deforming and not based on velocity blur don't forget to set Geo Time Samples to 2 in the Mantra rop.

Best regards,
Fabian

Thank you Fabian.

I thought the setting that you said should be the same as well.
I actually tested the setting at first.

But interesting thing is,
I tested with start 0 end 0.5, start 0.25 end 0.75, first on frame, center on frame , end on frame in softimage,
shutter time 0.5, trailing, centered, leading in Houdini,
And center on frame in softimage makes the worst match…..
Closest one was
Softimage: start 0, end 0.5, first on frame.
houdini: shutter time 0.5, trailing.
But my situation is we do not want to change softimage settings.

So I think the offset in softimage (start and end) makes this problem since houdini does not have offset for shutter open/close.
I checked softimage motion blur settings. shutter angle 180 degrees is start 0, end 0.5. basically same with maya. (maya has shutter angle separately though)
But I do not know and am really curious how to make offset in Houdini. like shutter open 0.25 end 0.75.

I like the simple shutter settings in houdini but also I hope mantra motion blur or camera setting will have more control for H12. like Render man style (shutter angle, shutter speed, open time/ close time and stuff)

Addition,
the camera also moving, character animation is from point cache, I tested the results above with xform sample 2, geo time sample 2. also tried higer settings like 10, 10.

Thanks again Fabian!!

I checked softimage motion blur settings. shutter angle 180 degrees is start 0, end 0.5. basically same with maya. (maya has shutter angle separately though)
But I do not know and am really curious how to make offset in Houdini. like shutter open 0.25 end 0.75.

0.5 in Houdini is 180 degrees

Addition,
the camera also moving, character animation is from point cache, I tested the results above with xform sample 2, geo time sample 2. also tried higher settings like 10, 10.

You should render using geometry motion blur > refer to the help .

rob

Hi,
attached is the result from my little test. There are some look differences due to shading but the position of the geometry evaluation is the same.

Also I'm not sure you need geo velocity blur with a point cache as you are not changing point count and would have to generate the v attribute after the fact.

I'm also sure that the MDD reader is part of your problem. You'll need to read the same mdd in both xsi and houdini to get the same geometry interpolation between frames.

Lastly make sure Arnold gets fed a few deformation samples to work with as there seems to be some different interpolation going on in mantra vs. arnold. Turn down the arnold sample to 2 in this example and you'll see.

Attached is a setup that seems to work, compare images.
(xsi scene is 2012 and prob needs latest arnold installed)
(these are 25fps)

Best of luck,
Fabian

Thank you so much Fabian!!

I tried with Arnold ver1.5(I don't know it's latest) and I got exactly same result with you.
So problem was Arnold ver1.0 which we r using.
I don't think we r gonna update Arnold to ver1.5 for current project but I am pretty happy that I at least know what is problem.

And also I found how to make offset. it's kind ugly to do but need to offset Animation itself. Arnold ver1.0 with start 0.25, end 0.75 makes 0.25 frame delay so if I offset all animation coming from Softimage -0.25 frame with time blend and timeshift then fits with it.

About geo velocity motion blur and deformation blur, they do not make differences as long as point number don't change. It really depends on the situation though, I prefer not to use geo velocity for any character's animation with point cache with PC2 or MDD for using them as hold out. Because depend on sample, maya, softimage(more like mental ray or arnold) motion blur can have not linear motion blur but geo velocity blur can be only liner.

Anyway, I really appreciate it!!

Thank you!!

You're welcome. Always fun with these little troubleshooting puzzles
Fabian