HowTo:Fix artifacts

On occasion, some objects in your scene may have speckles or what looks like random noise on the surface. Below are a few possible causes:

Coincident Surfaces

• Two or more surfaces occupy the same plane. The choice of which surface gets rendered varies from pixel to pixel according to the whim of POV-Ray. Translating one surface by 0.0001 out of the plane will usually fix this. This is probably the most common cause of 1px speckles on specific objects in a scene.

See Documentation:Tutorial Section 2.1#Co-incident Surfaces.

Radiosity

• In scenes using radiosity, if the artifacts show up only when radiosity is turned on, then they are caused by radiosity sampling errors. If you haven't already done so, check the Official Documentation on Radiosity or the HowTo: tutorial on radiosity.

Transparent and Reflective Surfaces

• Scenes that many reflective/transparent surfaces may run afoul of the default max_trace_level setting. Check the messages from the render, as POV-ray will tell you if the max_trace_level was reached during a render. If it was reached, raise the max_trace_level to a higher value.

Other Causes

• You've rendered a scene using certain textures with anti-aliasing turned off. The difference caused by the use of anti-aliasing can be startling, especially with a texture which is supposed to have weird speckles! ;-) Note that the appearance of speckles on a surface is not only controlled by the pigment statement, but can be the result of a small, bumpy normal, or the use of crand in the finish statement.