Light Rig

Mr_ E

The bus interior is too dark. I tried using a light rig but it didn't brighten the bus interior, even after I positioned the rig's lights using their camera view. Why isn't the light rig working? 

SickleYield

Add more lumens in the lights' parameters?  Sometimes default settings are a power of ten lower than a scene needs depending on the tone mapping and other factors.

JonnyRay

Also check your surface settings on the bus windows. It looks like light from outside isn't making it to the interior of the bus. If you set "thin walled" to true on a surface, Iray treats everything behind it as if it was part of the glass when calculating lighting. So it wouldn't transmit the light from outside to the interior.