Gradient: you may define a Color Range by clicking in the color boxes, and the min/max values determine the magnitude of tint applied, from 0 to 100%. Use Min=0 and Max=0 to disable the effect.

Map: Forest uses a custom map as tinting source. With "Random Values", a random pixel from the map is taken for each tree, and "As Texture" applies it as a standard Max texture.

By default, Forest uses the parameters defined in the Distribution Map rollout (X/Y, offset, rotation...) for scaling, but it's also possible to get the mapping coordinates from the surface, enabling the "Get UVW from Surface" checkbox. A ground object must be assigned in the Surface rollout to use this mode.

Use on Custom Objects: applies the random tint to the trees created from "Custom Object" sources.

Caution: Random Tint needs "Forest Material" to work. Be sure that the materials used in the Forest object (assigned in the Geometry rollout or applied directly to the object) uses the "Forest Material" plugin as a base. Without it, these effects won't work.

It's possible to customize the tinting options for each material using the "Override" option in "Forest Material". This feature is specially useful for mesh trees that use a Multi-sub material (as mat.ID 1 for trunk, mat.ID 2 for leaves). This mode allows you to apply different tints for leaves and trunk (or disable it). See "Forest Material" reference for details.

Note: For users coming from Forest 2: you will notice that all options of fixed/random Material ID have been removed. This is because Forest 3 can use multiple types of trees, each one with its own Material, using the parameters of Geometry rollout. So, you can forget about creating and applying the multi-materials manually, the plugin does it automatically.

Forest Shader

Forest includes a custom shader that enhances the rendering of billboard trees. Currently, it's only available for Mental Ray. The following parameters adjust the behaviour of this shader. As all options on this rollout, require the use of materials based on "Forest Material" plugin.

Trace Depth: Maximum raytrace depth used to compute the transparencies, default value is 3.

Opacity Level: Defines the minimum level of opacity of the mask textures used by Forest Material. As instance, a value of 0.8 considers all pixels darker than RGB=204,204,204 (255*0.8 = 204) as opaque. It's used to optimize the computation of opacity maps.

Fast Opacity: Other optimization parameter. Most of scenes work nice with it enabled, but would create image artifacts on the horizon when "Haze" effect is enabled on Sun & Sky solutions (mr Physical Sky).

These last parameters are used to speed up rendering, but in some situations using lower values would create image artifacts. To disable them use Trace Depth=99, Opacity Level=1.0, Fast Opacity unchecked.

Global Illumination parameters

Self-illum factor: This parameter works as a multiplier of the self-illumination value, for all materials used by the Forest object. Use it to adjust the Self-illum effect, without having to modify each material individually.

Irradiance Color: Defines the effect of global illumination on the Forest object when "Final Gathering" is enabled (Mental Ray renderer options).

To get the best results with these parameters, we suggest this configuration for Mental Ray scenes:

With Final Gathering enabled:

Forest Self-illum factor: 20% to 100%
Material Self-illum: 50%. Create all your new materials with this value, you won't need to modify it... use SI factor instead. All materials of the Forest libraries have 50% by default as well.
Irradiance Color: default
Use SI Factor + Irradiance to get the desired global illumination over the trees.

Final Gathering disabled:

Forest Self-illum factor: 20% to 100%
Material Self-illum: 50%.
Irradiance Color: not used