Iray Programmer's Manual

Implicit groundplane

An additional implicit "shadow catcher" groundplane can be specified. This plane weights the environment contribution of the ground using a progressive estimation of the amount of shadow on the groundplane, caused by the objects in the scene (from direct light only). The mode of the environment lookup itself remains unchanged as it is specified by the environment dome settings.

The groundplane is controlled with the following attributes on the mi::neuraylib::IOptions class, shown here with their default settings:

bool environment_dome_ground = false

Controls whether the implicit groundplane is enabled or not.

mi::Float32_3 environment_dome_ground_position = mi::Float32_3(0,0,0)

The origin of the ground plane.

mi::Color environment_dome_ground_reflectivity = mi::Color(-1,-1,-1,1)

If set to a positive value, enables reflectivity on the groundplane weighted by the fresnel term.

mi::Float32 environment_dome_ground_glossiness = 100000.0

Controls the glossiness of the ground reflectivity. Useful values range from 0 (diffuse) to 100000.0 (perfect mirror).

mi::Float32 environment_dome_ground_shadow_intensity = 1.0

Controls the intensity of the shadow on the groundplane with a value greater or equal to 0.0. A value of 0.0 denotes no shadow at all and a value of 1.0 denotes regular shadow intensity, thus values between 0.0 and 1.0 denote a lighter shadow. Values above 1.0 increase the shadow intensity. Note that the range of useful values above 1.0 is rather limited and exceeding this range may lead to an unnatural dark shadow that can influence other additive lighting effects, such as reflections of the objects in the scene. The exact useful range is scene dependent.

mi::Float32 environment_dome_ground_texturescale = 0

Used to control the texture projection of the environment on the ground. This can be seen as an equivalent to the distance from ground where the real life camera was placed to take the captured environment map.