Problem trying to create a light emitting material in Blender


Hi everyone, just got started with this amazing looking renderer.

I am wanting to create a light emitting object in Blender, using the path tracer engine, but can’t get it to work. It works fine in the SPPM engine, but would rather not it right now, as the render times shoot up massively.

When using the emission shader in the material, the material preview looks as it should, but the render does not show this at all. I have also tried using many of the surface shaders in combination with the emission shader, but to no avail.

So I thought I would try the OSL node system. I have been using the ‘asBlackbody’ node. I sometimes get the material preview showing the glowing ball like the ‘emission shader’, but most of the time it shows nothing. Even with regular shaders like the Disney shader, I just get a black ball.

The bigger issue with the OSL nodes, is that at render time, the render completes in three seconds and shows nothing but the checker panels.

Clearly I am doing something wrong here. If you could suggest a fix, I would be most grateful. I have attached a screen shot of the problem.


Hi @fxgogo,
Two quick suggestions:

  1. If you add an emission shader to a material then check the surface normal direction. The emission is directed only towards one side. If you have a an emitting plane, you may have to look which side is the emitting one.

  2. To use the asBlackbody osl node you need to connect it to the Emission Color input of an asStandard material (see screenshot)


Great stuff Mango3, that makes total sense, my object is a plane at the moment. I will make the modifications tonight and will feedback the result.


You nailed it on both suggestions Mango3. Thanks. Here is the result.


Great that it works now. Keep us updated on your experience with appleseed.