Sun and Sky
	A sunlight system, when partnered with Physical Camera settings, gives the user a great range of flexibility in creating accurate daylight renderings.
Part of	VRay
Part Type	Entity
Screenshot	[[File:|320px]]

Introduction to Sun and Sky

The sun's intensity and angle are important to consider when lighting a scene, especially for exterior renderings. Using a sunlight system will produce lighting that is accurate to the site's date, time, and location.

Once a sun is placed within the model, a sky needs to be added in V-Ray so that V-Ray knows where the sunlight is coming from. The sun and sky work together in V-Ray to create a more realistic rendering.

Sunlight

Sunlight is simulated in Rhino by creating a Directional Light . There are separate options for the light in Rhino and in V-Ray. The advantage to creating a sunlight system through V-Ray by using the SunLight command is that the parameters for sun position, date, time, and location for the sun can be edited so that the light is as close to reality as possible.

Sun Angle Calculator in V-Ray

Use the SunLight command, or click on the yellow asterisk icon, to place a directional light that is accurate for a specific date, time, and location. In the Sun Angle Calculator, uncheck "Control sun position manually."

Remember that the orientation (North, South, East, or West) of the model matters. The compass under Sun Options shows which direction is North. Make sure that the northern side of the model is facing North according to the compass. By default, North is at 90 degrees, which is in the direction of the y-axis.

Enter the date and time of the scene, or click on the "Now" button to set the time automatically to the current time. Set the location of the scene by searching for the city, state, or country. The latitude, longitude, and time zone can also be edited, but it is easiest to search by a named location.

After clicking okay, click anywhere in the model to place the directional light object. Remember that the actual position in the model of the light object does not matter because the arrow merely denotes the direction of the sun's rays.

There are three ways to change the sun's position. In Rhino, the position can be edited manually using control points. Or, click Modify in the light object's properties (the Sun Angle Calculator should appear, and the sun can be repositioned from here). The easiest way is to delete the light object and use the SunLight command again.

Options in Rhino

For options in Rhino, select the sunlight and use the Properties command. Select Light from the drop down menu. See Directional Light for the options for directional lights. (If the light's options are edited in Rhino, be sure to uncheck "Override Sun's parameters" in the Texture Editor in V-Ray .)

Here are some examples of how V-Ray will render different Turbidity settings.

Here are some examples of how V-Ray will render different Ozone settings.

Sky

For the sky to render, edit the GI (Skylight) and Background options, which are found in the Environment rollout in the V-Ray Render Options. This will change the source of global illumination (GI) in the scene, as well as the appearance of the background in the rendering.

Texture Editor in V-Ray

First, make sure that GI is on (this option can be found in the Indirect Illumination rollout). In the Environment rollout, click on the "M" next to GI (Skylight). In the Texture Editor, change the sunlight source and select the correct directional light that was created using the Sun Angle Calculator. Uncheck "Override Sun's parameters" if the options for the sun have been edited in the Light Properties in Rhino; otherwise, leave the box checked and edit the turbidity, ozone, and multiplier from the texture editor.

To create a background, click on the "M" next to Background and repeat the same steps as above. Now, the color of the skylight should have an influence on the color of the light in the scene. Shadows should also correspond to the angle of the sun.