Is there a way to work around Surface Particle Generators

[EDELVIZ_ARCH]

Hi Everyone,

it is fantastic to see how quickly VRay generates and render the modo replicators and how easily they are rendered. It is so nice to be able to render this complexity with such ease!
But this makes a Modo problem very obvious which again gets in the way of really being able to use this feature - Modo creates the particles that are used for the position of the replicators take a huge amount of memory and performance. Would there be any way to generate this position information at rendertime only and in a more efficient way? Is there any way to do that already with VRay atm?
And if not, could I shamelessly ask for it as a feature request? Maybe a rendertime multiplier that creates additional replicas between the already submitted ones?

To replicate(Pun intended) the problem - just draw a big plane in modo, add a surface particle generator to it and change the particle ceiling to 10 Million and see that the performance and memory usage.

Thanks and all the best,
Jonathan

[kubbek]

It is not a perfect workaround but freezing particle generator helps a lot with performance issues because the program doesn't have to evaluate their position all the time.

Jakub

[EDELVIZ_ARCH]

Dear Jakub,

thanks for your reply. Yes that is what we do all the time. This works well till about a million replicas.
But once you go beyond 10mio replicas your filesize explodes and the viewport is terrible.

Cheers,
Jonathan

[kubbek]

I am deffinitely interested in a solution as it is a problem we are also facing...

[vladimir.nedev]

It is actually MODO that generates the particle positions/transformations. We only render the data.

For the view-port, you can use the Display Density parameter in the Replicator.
Valid values are between 0 and 100 percent.
If you set it to 10%, only 10% of the replicas will be shown in the OpenGL viewport.

There is also a Render Density parameter, but again valid values are only between 0 and 100 percent it seems,
so you cannot add additional particles to those provided by the Point Source.

There is a Render Multiplier parameter, which can have values above 1, so it can generate additional particles.
But it didn't seem to work very good in my tests, it adds the new particles very close to the original ones, using the same random offset/twist/scale.
Maybe I was using it incorrectly.



We could in theory add a V-Ray Instancer item, similar to the one we have in V-Ray for 3ds Max.
Then all the particles can be generated only when rendering with V-Ray.
But it will be a lot of work to integrate it as good as the MODO Replicator.

Greetings,
Vladimir Nedev

[vladimir.nedev]

Actually I didn't check how the V-Ray Instancer works in V-Ray for 3ds Max.
It actually uses a pre existing particle system for the position of the instances.
In MODO we would have to implement both a V-Ray Instancer/Replicator item and a V-Ray Surface Generator item to generate the particle positions and orientations.

Greetings,
Vladimir Nedev

[Robert]

The best thing so would be Vray Multiscatter. Not Chaos Group plugin, but really helpful. Else I agree its the job of Modo. Maybe they know an easy way to integrate Vray Instancer too.

[vladimir.nedev]

Have you tried setting the Replicator to Visible -> No, Render -> Yes ?
In this case you have no preview at all in the OpenGL viewport, but it seems MODO won't generate any particles until render time.
Even more impressive, it seems that the particles are not regenerated between renders unless you have changed some property of the surface particle generator.

Greetings,
Vladimir Nedev

[EDELVIZ_ARCH]

Hi Vladimir,

thanks a lot for looking into it and doing tests. I was trying what you said but am not able to work.
If I set the display density of the spg to 0 it still takes the ram (see image attached)

And if I hide it via the eye symbol and then set it to render:yes it will not render the replicas - neither in modo nor vray (see 2nd image attached)



So if the Visible:No, Render:Yes would work it would be great. But this is something that I have requested since Modo 701 and have little faith that it will come any time soon. Unless of cause, you can give the Modo developers a nudge and ask them to get it to work.

Cheers,
Jonathan