Octane & 3dsmax pFlow particles motion blur issue

Sat Oct 31, 2020 11:07 am

Hi.
I'm facing this issue I can't resolve with the pFlow particles motion blur going wrong when using a "Delete particles by age" function.
Here is what I want to achieve (green lines):

And here is the issue I get if I use a "delete by age" inside the particleFlow (green lines):

The blue lines are particles emitted with the new TyFlow 3ds Max plugin. TyFlow makes no issue in the motion blur of the particles when using the same "Delete" event.

I've been tweaking so much parameters, and it will be so long to explain by text that I did a video to show you all the details :
https://matias.fr/owncloud/index.php/s/CJ65qAux5u0LpXH

Update : I've been playing with the Octane Global Preferences parameters (pFlow tab), without success...

And please, no answer like "why don't you use X-Particles on Cinema 4D", or "use ThinkingParticles ... " , thats not the point.
Regards.
Carlos.

Thu Nov 05, 2020 2:34 pm

Hi cmatias,
I sent the glitch issue to the attention of developers.
Regards
Paride

Fri Nov 06, 2020 12:10 am

Hi cmatias,

Thank you for the video, and for explaining this issue.

It seems you are using a mode that get all particles into a single mesh, and that can create issues with motion blur when some particles are deleted.
(basically, the 2 meshes used for motion blur have a number of vertices that do not match, in some cases)..

There are basically 2 ways for getting the PFlow particles geometry to Octane:
-All particles in a single big mesh
(that is simple, and probably more 'stable' as PFlow do all the work, and all particle effects should be visible)
-All particle positions and 1 or more small mesh used for each particles (instances)
(that is much more efficient, and should solve the motion blur issues. Some of the particle effects may be ignored..)

One way to see witch mode is actually used by reading the 'Primitives/Meshes/Voxels:' numbers in the viewport:
eg: 12120/4/0 with a single big mesh (most of the 12120 triangles), versus 456/976/0 for Direct mode (976 count the particle instances and other meshes)

* Solution 1, keeping the single mesh mode:
You need to replace the kill by age with something else, that would keep particles, but set them invisible
(eg, changing their scale to 0, applying a material with opacity 0, ...)
I'm not sure how to do this with PFlow, but I guess that's possible..

*Solution 2, switch to instance mode (Direct mode):
In Render settings, Support tab:
Common Scene Collection Settings rollup:
-Use Direct geometry handler : ON
-Use Direct particle : ON
PFlow rollup:
-PFlow Support type : Direct
-Override PFlow Render mode : ON
-Use PFlow Render mode percent: ON
-Discard PFlow Multi Mesh Motion Blur: ON

Note that the Direct mode may use the orientation of the PFlow object incorrectly, if they had some transformation.. (source objects, force helpers, etc)
In this case, it might be better to re-create new ones in the correct orientation, and switch to those, in the Particle View..

See this sample, the PF Source 002 is working fine with kill by age and motion blur (but the hidden PF Source 001 had issues with orientation)

PFlow_KillByAge_MB_DirectOk.zip: (42.48 KiB) Downloaded 147 times

Note that there are some update issues when changing some settings, like the PFlow Particle Velocity scale in the Render setup / Tools / PFlow dialog..
The work around is to close the viewport, select 'Clear Octane Scene' in the Octane main menu, and re-open the viewport..
(the Rebuild Scene button in the viewport is supposed to do this, but PFlow systems seems to loose track of their particles in this case..)

Also, you can also investigate the motion blur effect and issues by changing the Shutter time (Render setup / Camera / Motion blur) from 100 to ~5.

I'll try to improve the update and make the user interface more clear about the current mode actually used..

On a side note, PFlow is quite old, and TyFlow seems to be a very good replacement, more simple and reliable, on the renderer side, and I hope it can be stable enough some day soon, for you to switch..

Thanks,