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Note there are three main ways to light a scene:

• Analytic Lights - These are the preferred choice. These provide superior memory usage, flexibility, and speed.
• Mesh Lights - These are great for using arbitrary shapes in lighting. These consume more memory since they are geometry and complex shapes may increase noise.
• Emissive Surfaces - These typically use a constant bxdf or "glow" parameter to light a scene indirectly. This is inefficient and should usually be avoided but may be useful for texture mapping "lights" onto futuristic objects and panels!

Analytic Light Types

• PxrDomeLight - The domelight acts as the environment light for a scene and is often mapped with a high dymanic range image (HDRI).
• PxrRectLight - The rectlight is the commonly used rectangle-shaped area light.
• PxrDistantLight - This light is perfect for use as a Sunlight or other distant source where light rays are nearly parallel and cover the whole scene.
• PxrDiskLight - Great for using as an area light or in combination with filters to make a spotlight.
• PxrSphereLight - For users that miss using a point light, this light can be useful to illuminate in all directions.
• PxrEnvDaylight - A daylight simulation shader where you can supply any time and location on Earth or simply place your sunlight where you like it.
• PxrPortalLight - For difficult lighting situations like indirectly lit interiors, this light along with the PxrDomeLight can be used to increase the quality and speed of your renders.