Light

A light source is used to shade objects to try to reproduce realistic lightning in virtual scenes. Lights and shadows are important aspects of a immersive virtual scene. The problem is that they have to be modeled in the virtual world by hand, tuned and optimized. The results greatly depend on it.

There are different light sources:

• Point
• Directional
• Spot
• Photometric

Common Light Parameters

Every light source has the following parameters:

• On/off
• Colors for diffuse, ambient and specular
• Attenuation parameters
• light beacon

Point light

This is a light source defined by a position in space. The orientation does not play any role in this case.

Directional Light

This light source uses only the direction of the light beacon, it emits parallel rays, similar to sunlight on a planet surface.

Spot Light

The spotlight is similar to the point light, but is further limited to emit light in a small cone. The light cone is oriented depending on the ligth beacon orientation.

Photometric Light

A photometric light is a pointlight that modulates the emitted light using a texture containing the measurements of the light intensity in candela. Those are usually IES files, PolyVR converts them to a texture internally. Photometric lights allow to create much more realistic lightning than any other light source above.