Delayed Load and Nice Motion Blur

[Div]

Hi, I'm doing swarm of bees, by instancing animated objects on particles using mantra delayed load. Mantra renders fine motion blur, but as the bees move very fast it renders big lines instead of nice smoothed curves. I used to increase the Geo times samples, but this doesn't work in this case. From the delayed load help : "This procedural only supports one segment of motion blur (2 geometry samples)", argh! no nice blur.... Is someone here found a solution to get more than 2 samples with a mantra delayed load ??

Thanks a lot for your further help..

[tomhanks]

I had a problem just like that, try to raise the oversampling parameter in the popnet node.

If you want to achieve curved motion blur you have to use deformed motion blur not velocity motion blur, so in the point motion blur type switch to "compute subframe geometry".

play the file some frames and render it see if it works, in my case I could make it work, but it didn`t work with cache so I tried to render without it and it worked in my case.

I hope this helps.

Cheers!

[Marc]

The delayed load is fairly crippled in that regard. Anything other than velocity blur is almost guaranteed to fail really. You could try using the clusterThis procedural from Mark Story, that might be more configurable.

Cheers

Marc

[Div]

@tomhanks : the problem is that the particles are cached to disk...

@Marc : Thanks, i'm going to look in that way...

[pclaes]

Here might be a hack that works just for this scenario. Perhaps you can take 4 positions of your particles and create a curve, then a surface. This is very similar to what they did for the pinguins in Madagascar or the superfast motionblur of the squirrel in Over the Hedge. This surface then represents your fast moving object.

http://www.stoneschool.com/Work/Siggraph/2006/#CartoonMotionBlur

http://portal.acm.org/citation.cfm?id=1179968&dl=GUIDE&coll=GUIDE&CFID=73566324&CFTOKEN=18864275

Your delayed load geometry then becomes the surface generated from the curves. This is probably "easier" to do with a custom dso.

[realer]

@tomhanks : the problem is that the particles are cached to disk...

@Marc : Thanks, i'm going to look in that way...

caching particles to disk should not cause a problem if you want to keep the oversampling.. just write all subsamples out too.. so instead of $F use something like $FF in the file expression and set the steeps to 1/(the number of oversampling steps)

-- now for the tricky part: to get this working with deformation motion blur the timeblend has to be modified so it handles the substeps instead of the full frames.. basicly you need to change the expressions inside so they dont read full frames but the closest subframes ($F+X/oversampling)

but again this will just give you the motion blur for the particles movement, it wont give you motion blur for example the wings movement on the delayed loaded bee.

hope this helps.

[Div]

I'm going to try that, thanks... I get motion blur on the wings movement by processing the velocity of the geometry before writing it to disk, then enabling "use velocity motion blur" on the mantra delayed load shader..

[tomhanks]

caching particles to disk should not cause a problem if you want to keep the oversampling.. just write all subsamples out too.. so instead of $F use something like $FF in the file expression and set the steeps to 1/(the number of oversampling steps)

-- now for the tricky part: to get this working with deformation motion blur the timeblend has to be modified so it handles the substeps instead of the full frames.. basicly you need to change the expressions inside so they dont read full frames but the closest subframes ($F+X/oversampling)

but again this will just give you the motion blur for the particles movement, it wont give you motion blur for example the wings movement on the delayed loaded bee.

hope this helps.

When you say time blend, you mean the node time blend?

[realer]

When you say time blend, you mean the node time blend?

yes the timeblend node.. its needed if you cache stuff and still want deformation blur with multiple samples.