Troubleshoot global illumination doesn’t work or looks incorrect

The problem is any of the following:

• Global illumination is not turned on. If you did not use the global illumination presets (see Render with global illumination), it might be turned off.
• Raytracing is not turned on. If you did not use the global illumination presets (see Render with global illumination), it might be turned off.
• If caustics is not turned on, too many photons may have migrated from the global illumination photon map to the caustics photon map. For more information, see GI photon maps vs. caustic photon maps.