1. Working with Environment Lighting Part 2
ARCH63114/ARCH51348
Computer Rendering

2. The VRaySun and VRaySky are special features which are provided by the V-Ray renderer. Developed to work together, the VRaySun and VRaySky reproduce the real-life Sun and Sky environment of the Earth. Both are coded so that they change their appearance depending on the direction of the VRaySun.

3. The VRaySun is located in the (Create - Lights - VRay) panel
The VRaySun is located in the (Create - Lights - VRay) panel. You can also specify the VRaySun as the sun type inside a 3ds Max Daylight system.
The V-Ray Sun and Sky are based largely on the SIGGRAPH'99 paper "A Practical Analytic Model for Daylight" by A. J. Preetham, Peter Shirley, Brian Smits. For a more complete list of references, please see the Links and references section.

4. Invisible - when on, this option makes the sun invisible, both to the camera and to reflections. This is useful to prevent bright speckles on glossy surfaces where a ray with low probability hits the extremely bright sun disk.
Turbidity - this parameter determines the amount of dust in the air and affects the color of the sun and sky. Smaller values produce a clear and blue sky and sun as you get in the country, while larger values make them yellow and orange as, for example, in a big city.
Ozone - this parameter affects the color of the sun light. Available in the range between 0.0 and 1.0. Smaller values make the sunlight more yellow, larger values make it blue. For further info, please see the Examples section.
Intensity multiplier - this is an intensity multiplier for the VRaySun. Since the sun is very bright by default, you can use this parameter to reduce its effect. Start with low number

5. Size multiplier - this parameter controls the visible size of the sun.
Shadow subdivs - this controls the number of samples for the area shadow of the sun. More subdivs produce area shadows with better quality but render slower.
Shadow bias - moves the shadow toward or away from the shadow-casting object (or objects). If the bias value is too low, shadows can "leak" through places they shouldn't, produce moire patterns or making out-of-place dark areas on meshes. If bias is too high, shadows can "detach" from an object.
Photon emit radius - determines the radius of the area, in where photons would be shot. This area is represented by the green cylinder around the Sun's ray vector. This parameter has effect when photons are used in the GI solutions or caustics.
Exclude - this button allows you to exclude objects from illumination/shadow casting for the sun light.

6. Example 1: Direction of the VRaySun light
This example demonstrates the effect of the sun direction. Note how in addition to the scene brightness, the sun position also changes the appearance of the sky and the sun light color.
Enabled: on, Turbidity: 3.0, Shadow subdivision: 8, Intensity multiplier: 0.01, Size multiplier: 1.0

12. END