author Florian Link
package MeVisLab/Standard
dll SoPathTracer
definition SoPathTracer.def


The SoPathTracerBackgroundLight module provides a background light for the SoPathTracer. It supports setting a top, middle and bottom color or alternatively it support image based lighting (IBL) using a sphere or cube map. Only one background light can be active for a given SoPathTracer.

A sphere map needs to be a quadratic 2D RGB color image. A cube map needs to be a quadratic 2D RGB color image with 6 z-slices. The z-slice order for the cube map is: pos x, neg x, pos y, neg y, pos z, neg z. The input image can also be a equirectangular projection image (aka HDRI), in which case the image has to have width = height * 2. There is an example network with a cube map.


In this rendering, a strong environment light is used, which you can see from the strong reflections on the creasing angles.


Default Panel


Input Fields


name: inHDRLight, type: Image

The sphere or cubemap.

Parameter Fields

Field Index

Attach To Camera: Bool Render Source Intensity: Float
Bottom: Color Rotation: Rotation
Convert from sRGB: Bool Top: Color
Enable image based lighting: Bool  
Enabled: Bool  
Intensity: Float  
Middle: Color  
Render Source: Bool  

Visible Fields

Enable image based lighting

name: useIBL, type: Bool, default: FALSE

Enable IBL.

Attach To Camera

name: attachToCamera, type: Bool, default: FALSE

Attach the background light to the camera.

Render Source

name: renderSource, type: Bool, default: TRUE

Render the background light for rays that only hit the background.

Render Source Intensity

name: renderSourceIntensity, type: Float, default: 1

Sets the intensity of the background light rendering in the background image.

Convert from sRGB

name: sRGB, type: Bool, default: TRUE


name: enabled, type: Bool, default: TRUE

Enables the light.


name: intensity, type: Float, default: 2, minimum: 0, maximum: 5e+06

Sets the intensity of the background light.


name: topColor, type: Color, default: 0.333333343267441 0.666666686534882 0.498039215803146

The top color.


name: middleColor, type: Color, default: 1 0.666666686534882 0.498039215803146

The middle color.


name: bottomColor, type: Color, default: 1 0.666666686534882 0

The bottom color.


name: rotation, type: Rotation, default: 0 0 1 0

An extra rotation which allows to rotate the background light (colors/sphere/cubemap).