Motion blur, when?

[mmrender]

Other question about animation. I would like to apply motion blur to the camera in the animation I'm doing (see post http://www.chaosgroup.com/forum/phpB...ic.php?t=15371 ) and I wonder if you should "check the box" of motion blur option when calculating the irmap or only when rendering the frames, or both?
How it will affect the render times?
In the case of the frames I posted in the other treat I applied the motion blur only in render pass.

When searching for Motion blur in the forum I come across one post speaking about to apply motion blur in postprod using combustion and EXR images. It looks a little advanced for me, but, that would be the proper aproach?

Thanks,
Manuel

[studioDIM]

It's a lot easier if you use RPFs (but they're fairly bigger) to do moblur in post with combustion.
It's a 2.5D blur, so it's not 100% phisycally accurate, as the 3D moblur in VRay.
The difference in speed is big, though.
VRay has to calculate (sometimes a LOT) more stuff to give you proper blur, combustion does it in realtime or thereabouts, as a "D and a half filter.

You should not be noticing many a difference in visual quality between the two though, with your kind of animation.

Moblur, afaik applies only to the RGB pass in VRay, so it has no influence on the rendertime of IRMaps, wheter it's checked or not.

Hope it helps

Lele

[Candelero]

There is a slight difference. Basically the irmap will be stored differently with MB checked on, and when off. So having the MB before the GI passes will affect it.

If you are using the Image MB (Effects), then there is no difference, as it is produced after the rendering.

Best regards,
nikki Candelero

[studioDIM]

There is a slight difference. Bsically the irmap will be stored differently with MB checked on, and when off. So having the MB before the GI passes will affect it.

I didn't know this.
In what way is the irmap different with moblur on?
Will it be calculated per subframe?

Thanks for the infos, Nikki

Lele

[mmrender]

I had the suspicion that MB affects irmap calculation because in the online manual there is an option

Prepass samples - this controls how many samples in time will be computed during irradiance map calculations.

So, I supposse that has somehow influence

Manuel

[panthon]

It's a lot easier if you use RPFs (but they're fairly bigger) to do moblur in post with combustion.
It's a 2.5D blur, so it's not 100% phisycally accurate, as the 3D moblur in VRay.
The difference in speed is big, though.
VRay has to calculate (sometimes a LOT) more stuff to give you proper blur, combustion does it in realtime or thereabouts, as a "D and a half filter.

Lele

How much RPF motion blur do u apply in combustion? I find i have to pump the values beyond 50 to actually see any Motion blur on the image...
In vray a value of 0.5 does it for me, as it used to be in reelsmart motion blur too...

[Austin]

If it's a flythru with nothing moving in the scene, why would you tick on moblur for irradiance map calc? I mean since the scene is static, shouldn't you calculate the irradiance map as a static map, then blur that according to the camera's motion? If there were animated objects that would be changing the irradiance data from frame to frame I could see using moblur with calculation there, but at that point you probably wouldn't be using saved maps.

Correct me if I'm wrong on this; I've never done this but it seems logical.

[studioDIM]

How much RPF motion blur do u apply in combustion? I find i have to pump the values beyond 50 to actually see any Motion blur on the image...
In vray a value of 0.5 does it for me, as it used to be in reelsmart motion blur too...

Well, when i am in post i do things to the eye

The combustion moblur is a bit less sensitive than reelsmart, it seems to me, but the same value (say 50) will blur more the faster objects.
So the faster your object is, the more blur it'll get.
The effect can be very subtle if it's just a camera pan (reelsmart can definitely exagerate the blur a lot more), but try a quick turn or similar, and you'll see it clearly.
Also, i tend to use it only with 32bpc rpfs, as the added precision and range does benefit the velocity channel.

I ain't sure i answered, though...

Lele

[studioDIM]

http://rapidshare.de/files/21167984/..._blur.mov.html

Small animation done with rpf moblur.
The jittery behaviour of some of the boxes is due to a strange reactor problem, not to the rpf moblur.

Notice that the shadows of objects aren't blurred unless there's a camera move, and that if the object changes shape in time, that won't work well at all
It does resolve nicely the object trails overlaps, and the quality is greatly enhanced at higher resolutions (there's some noise in the moblur, which ain't present at PAL res, for instance).

rendertimes per frame were around 4 seconds on my athlonxp 2800+.
rpf size with 4 channels (velocity, z, rendernodeid and coverage) at 32bpc were around 1.8 megabytes (this varies depending on scene complexity, of course), and to shrink their size i used the NTFS runtime folder compression (size on disk down to 1 meg).
In combustion, at this resolution, the moblur plus CC was realtime.

Lele

[mmrender]

Unfortunately here at the company, we don't have Combustion, only Adobe AfterEffects. Is it a way to apply something like that 2,5D motion blur using that software? I must admit that I didn't use very much until now.

Thanks,
Manuel

[studioDIM]

Up to 6.5, not with a filter.
Also, even when rendering out individual passes, the 16bpc max depth of ae 6.5 would lead to ugly results and artifacts.

I don't know for after that version: it depends if they smartened up and tried to support a file format which is 10 years old .
Judging from other things though, i'd say a priority for them would be to allow a user to REMAP the capslock key
Jokes apart, i haven't tried with any newer version.

Lele