I am working on a small stadium project and am trying to produce a night rendering with the field and stands around it lit up. I modeled in some traditional stadium lights as the source of the light. Within each light I painted the interior surface an emissive white material. This seemed to work well to light up the field in the preview, however when rendered the image ended up with sort of a grungy look to it. Can't share the full image, but here is a portion of it to get the idea of what I am talking about.
Not sure of how to fix this, and was wondering if anyone has ran in to this problem before and found a workaround.