Hey Krakatoa-users,
at the moment I try to render a nice particle animation with a ball I animated via motion capture of my graphic-tablet, wich emitts particles. The particles get disturbed with a wind and some box 3 stuff going on… I saved the particles (4Mio Particles over 550 frames, 100 partitions) and load them with PRT-Loader. Then I fade them out via Magma Flow. But now I have a problem when I’m rendering the scene. I got 3 Omni-lights in the scene (1 over the particles, 1 under the particles, 1 in front of the particles). When I render the scene the particle stroke got little black shadow rings arround it (I also attached a picture with it). I tried to increase the shadow-map size of each lights up to 4098, but then my PC crashes while rendering.
I hope anyone can help me to get a nice solution (Its no problem if the render would take a little bit longer. At the moment its arround 1:30min per frame)!!!
Thanks to everyone for the nice tipps in the forum!
Matthias
Quite possibly the Magma is producing a very high Density in the front regions.
Also, we recommend using Spot lights when possible as they use less attenuation maps (Omnis have to render 6 maps and are also not supported in Voxel mode).
Note that you can control the shadow density per light source, too. So it is possible to reduce the “lighting pass density” for each light individually (Omni > Shadow Parameters rollou, Dens. value), in case there is one specific light that is causing the problem.
But in your case, I suspect it is just heavy self-shadowing due to very high per-particle Density.
To follow up on the article Bobo linked too, you can improve your results by:
Generating your particles in the volume of the sphere instead of just at the surface (maybe the surface ± some thickness) if not doing so already. The usual cause of moire is too many particles being almost on top of each other.
Use magma to have the density of the particles follow a curve of some sort away from the edge of the ball, as opposed to having them go from no particles to fully dense particles right at the edge.
You can use the shadow filter radius spinner (next to the “Shadow Filter” dropdown in the Krakatoa Main GUI), to blur the particles more when drawing shadows. When the shadow filter radius is 2x or more than the drawing filter that will reduce moire patterns significantly.
Thank you really much guys!
At the moment I resave the PRT-files with an offset for an better result and it will probably run overnight. I also tried to replace the omnis with spotlight, but that didn’t fixed the problem completly, also the decrease of the densety made the resut better but not gone. I think it will be gone with the new offset of the particles. I will keep you updated and show the result of the resave!
