RE: Oh.. and rendering Ambient occ + motion blur..

[Harry Bardak <hb_xsimailinglist(at)hotmail.com>]

There are different way to tackle motion blur in XSI :

Option 1 :
You don't want to use Rasterizer, you want to use standard Motion Blur.

Rendertimes ( and also Quality of the MB ) Will depend mainly on the motion threshold that you got in the motion blur tab.
By default it is set to 0.2 0.2 0.2 0.2 which means that 5 sub frames will be calculated and merged. If you put 0.1 0.1 0.1 0.1 10 frames is processed.
You got more info on this at www.lamrug.org.

So basically if you put 64 samples on your AO shader you will have 64 x 5 samples calculated which is way too high. So you can divide your sample number per 5.
Activate jitter. You will get the equivalent quality as when you don't use MB and also fast render.

Option 2 :
Same as above but you control of the amount of sample according of motion vectors.
Guillaume Laforge did an article about this on xsi blog. It's one way to do it.

Option 3 :
Use rasterizer. To push too high sampling rate. ( 2 - 4 ) otherwise rasterizer will struggle with raytracing ( it s getting faster and faster with every version of MR by the way )

Option 4 :
Activate Fast motion Motion blur. This is a special mode that don't do any adaptative sampling. Put your min and max to same value and motion threshold to 0 0 0 0.
This strategy can be useful when you image is filled by a lot raytrace sample like Occ or glossy reflection. MR in this mode will not spend time to adapt the sample to what is needed or not.

Option 5 :
Camera projection technique. It's a 2 pass approach. First you calculate you image without Motion blur then you camera project the result with a constant shader. The motion blur will be very fast in this case.

Option 6 :
Post procces approach by outputing motion vectors. You need RealSmart motion blur plugin for Afx, Fusion or shake. Or you can subscribe in the beta shader forum on lamrug, and download the mi production shader.
You will have to generate the corresponding Spdl. This shader is an output shader that add motion blur after you render.


Enjoy.

Harry Bardak 

TD / Compositor. 



Http://perso.wanadoo.fr/harry.bardak/ 

+33 6 76 63 35 54

+44 781 661 4147

---

> Date: Fri, 29 Jun 2007 09:02:00 +0100
> From: chris(at)eclipsecreative.co.uk
> To: XSI(at)Softimage.COM
> Subject: Re: Oh.. and rendering Ambient occ + motion blur..
> 
> Isn't it better to render without MB then use that plugin for AFX, is it 
> Real Smart Motion Blur?
> Never used it here, but it's been mentioned a few times on the list.
> 
> 
> 
> Guillaume Laforge wrote:
> > You could create an occlusion shader with a motion threshold to switch 
> > between a high and a low AO sampling.
> >
> > Someone post an example here : http://www.xsi-blog.com/archives/119
> >
> > :)
> >
> > 1/2
> >
> > Guillaume
> >
> >
> > Alan Jones a écrit :
> >> Be sure to use the rasterizer if you're trying something as
> >> potentially intensive as ambocc with motionblur. Otherwise think
> >> number of AO samples multiplied by number of motion blur samples
> >> multiplied by number of pixel samples.... Ouch....
> >>
> >> Cheers,
> >>
> >> Alan.
> >>
> >> On 6/28/07, Lee Hallett <Lee.hallett(at)bbc.co.uk> wrote:
> >>> Whilst I'm making noise on the list, is it just the way it is, or a
> >>> bug/issue with rendering anything with ambient occlusion and motion
> >>> blur? The rendertimes went into the decades when I had both activated
> >>> for a (comically assumed) quick job last week. With ambient occlusion
> >>> and no motion blur, frames were sub minute, add on a little motion 
> >>> blur,
> >>> and expect retirement to hit home before the render...
> >>>
> >>> Surely this shouldn't be - also getting emormous memory requests from
> >>> mental ray (7 Gig for a very simple scene).
> >>>
> >>> Has anyone else had problems with motion blurr and ambient occlusion?
> >>> Worked around it, bt it was a bit of a concern.
> >>>
> >>> http://www.bbc.co.uk/
> >>> This e-mail (and any attachments) is confidential and may contain 
> >>> personal views which are not the views of the BBC unless 
> >>> specifically stated.
> >>> If you have received it in error, please delete it from your system.
> >>> Do not use, copy or disclose the information in any way nor act in 
> >>> reliance on it and notify the sender immediately.
> >>> Please note that the BBC monitors e-mails sent or received.
> >>> Further communication will signify your consent to this.
> 
> 
> 
> ---
> Unsubscribe? Mail Majordomo(at)Softimage.COM with the following text in body:
> unsubscribe xsi

---

Change is good. See what's different about Windows Live Hotmail. Check it out!