Strange object outline artifacts


I’m rendering a large collection of objects in random positions with varied lighting setups. Some of my objects show a strange artifact near their outline. My best guess is that it has to do with the specularity settings of the objects’ materials and how they interact with the lighting, but I’m having a hard time pinning down what combination of materials and lighting creates the artifact.

Does anyone know what kind of lighting setup might cause weird outlines like this? (Look at the edges of the chair - it may not be clear unless you view the image at full size). Might it be indirect lighting or ambient occlusion?

Thanks -

It could also be some anti-aliasing issues. If you don’t have the anti-aliasing samples high enough in the Render options, lines that aren’t horizontal or vertical (so some form of diagonal) will have a kind of jagged look which is kind of what I’m seeing.

check the material of the ground plain.
I think ‘z-transparency’ of the ground plain may be enabled,disable that and render it.