The properties on the Light Object control how the scene is lit.

Quickly set the other “Environment” properties to one of a variety of lighting situations: bright sun, overcast, moonlight, etc.

The properties in this group control the directional light hitting the tree (which can be considered the sun).

The color of the directional light.

How much directional light exists in the scene.

The properties in this group control both the ambient light hitting the tree and the colors shown in the background of the Tree Window.

The color used at the apex of the sky.

The color used for the horizon of the sky.

The color of the ground plane.

How much ambient light exists in the scene.

These properties allow you to tweak the result when you render Ambient Occlusion on the tree.

The new AO value follows the formula:
AOnew = ((AO + Brightness - 0.5) x Contrast + 0.5) x (Max - Min) + Min

Makes the AO brighter/darker.

Increases the difference between light and dark AO values.

Sets the darkest value of AO.

Sets the brightest value of AO.

Renders new ambient occlusion.

Clears ambient occlusion to white.

Sets the quality of shadows used. Higher quality equals sharper shadows, but also slower rendering in the Tree Window.

Shadow maps can be plagued with problems on the edges of objects. This property allows you to push, or “bias,” the shadow away from the light to avoid this problem. You most likely won't need to change this from the default.

Brighten/darken the shadow cast onto the ground, if needed. You most likely won't need to change this from the default.