appleseed Users Forum

Blenderseed lightning acts weird when using more than one light source

I’ve been trying to render things with the blenderseed renderer in Blender and it’s not quite working as I expected, and the lack of easy to understand documentation does not help. When I had just only area light (figured out these work the best, but correct me, if I’m wrong) all renders without problem, as shown here:

HOWEVER. If I add one or two more lights to the mix, small dots of light start to appear:

It does not matter which light is enabled, as long as it’s the only one enabled. If I enable only the light which caused me an issue in the previous render (in this example the rectangular light to the right), it renders without the dots. What am I missing? By the way, this was rendered with caustics on, SPPM lightning engine selected and 4 samples, 500 passes. I’ll be glad for any help on this, google and youtube are not giving any answers.

Edit: The only solution I’ve found for this is to render the light sources separately and then compositing them in photoshop, but that’s hardly a solution.

Hi @Yo_Nasha,

Welcome to our forum.
The issue you encountered seems most likely to be sampling related when several light sources are in a scene and SPPM is selected.
For our Max plugin we have a setting Importance Sampling which helps when multiple light sources are sampled.
We need have to look into this, thanks for the notification.


I made a quick test with a simple scene lit by 2 spot lights and SPPM integrator. I don’t see problems when using 2 lights (see screenshot) compared with only one light.
Setting up SPPM can be quite tricky, especially with larger open scenes. Assigning the main objects receiving light SPPM Photon Target under appleseed Object Options in blenderseed helps with sampling.
For SPPM best work focused emitters like spot or directional lights targeting the main object. Avoid diffuse environment lighting as only a few photons are directed towards the main object.