Lighting in OctaneRender® is generated using either an Environment node, one of the Octane-specific lights, or by connecting an emissive texture. Using an IESAn IES light is the lighting information representing the real-world lighting values for specific light fixtures. For more information, visit http://www.ies.org/lighting/. light profile texture geometry can be shaded to behave like a physical light in the scene.
By default, all light you see in an OctaneRender® scene when you first add geometry is generated by a white texture. When you add an Environment node to the scene and connect it to the Render Target, it overrides the white light. Adding a black texture environment to the scene creates a dark environment.