Particle emitter issues

Support Particles and Physics Simulations
1

Spray_Emitter
Spray_Emitter964×488 160 KB

Just looking for some help with this issues. In the image you can see that the partials are starting to show away from the emitter, where they are rendering fine in the view port.

I have tired hiding everything else in the scene to make sure nothing is interfering.
Turning down the normal velocity does help to bring the start of the emission closer to the emitter. But that isn’t really a solution.
Have tried playing around with the integration settings but no luck.

Has anyone come across this kind of thing before?

Thanks

2

I’ve had this problem before, unfortunately, I could not find a solution, so I cheated the render by compositing it later. I feel this is a bug, but Blender particles are known for a lot of bugs as well as lacking basic features… golly, they still don’t have a birth-rate option to turn particle emission on and off. Only thing I can say is to try and create a new scene and see if the issue persists, then you can narrow down the culprit. Are you willing to share the Blend file?

3

Thanks for that, I just tried rendering them in eevee and they work fine, so I will just render out the partials in eevee and comp them over the cycles render.

4

Could you provide a (simplified) blend file to show this issue… maybe someone can tweak one of the options… ( you know there are so much of them :wink: )… ?

( Maybe some Viewport Display → Children Simple/ Interpolated → Display As… and Amount setting or even something in the Min Distance of Falloff which may just be ignored in the vieport. )

5

Hi, I have managed to get the job out by rendering in eevee. But I am interested to see if there is a fix for this, I will try and get a scene up in the next day or two.

6

I have attached the scene if anyone wants to have a look, There are two emitters and both of them have the same issue, renders fine in Eevee but had the issue in Cycles.

https://www.dropbox.com/s/njq1et5r9mocg99/Partical_Emitter_Sample.blend?dl=0

Thanks

7

Indeed very interesting because i haven’t tried yet to animate the emitter… :thinking: and also haven’t seen this anywhere…

So weirdly enough if you enable Unborn under Particle properties → Render → Extra (maybe because of the animation… ?) then you get:

(( off topic: any options to loop this here directly ?? ))

8

Thanks for finding that, tried it here and it worked, couldn’t see your video.

So the help message that comes up if you hover over that button says it show partials before they are emitted, the seams like a weird option, why would you want that?

Problem with it that it means the particles are always there, render a frame before the spray starts you see they are rendering which of course would be an issue if you didn’t want to see them until the spray is meant to start. So you would still need to fix it in comp. The fact that it works with eevee without checking the box makes me think its just a bug?

9

If you click the point on the right side of Unborn (or mouse hover) then you can see: this is animateable…

Bug ?? IDK… maybe it’s just the fifferent handling of animated emitters in cycles ?? ( someone may call this inconistent behaviour… but this may come from different approaches… )… :person_shrugging:

10

I did have a play with it and I can see how you could use it, its not a fix for this situation as it shows the particles when you don’t want them.

The scene is quite small, I scaled the whole scene up and it fixed the issue, so there is some error with cycles and particles in a small scene.

11

Too bad… again thanks for the insight view of moving emitters :wink: