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


The SoPathTracerAreaLight module provides a physically based area light that illuminates the scene of a SoPathTracer. The lights can be rectangular or discs and have an area, color and intensity. They can be positioned with spherical coordinates around the bounding box of the renderer, or they can be position in world or camera space.

Since the light is physically modeled, it has a quadratic falloff. By default, the light intensity is adapted depending on the distance of the light to the center of the bounding box, so that the same intensity reaches the center of the bounding box.

There can be many area lights, but the performance will drop noticeable when using too many lights. A future version of the renderer might offer better performance for many lights by using a bounding volume hierarchy for the lights.


Default Panel


Parameter Fields

Field Index

Altitude: Float Intensity: Float
Attach light to camera: Bool Mode: Enum
Azimuth: Float Orientation: Rotation
Color: Color Position: Vector3
Diameter: Float Render source: Bool
Distance: Float Scale Mode: Enum
Enabled: Bool Type: Enum
Height: Float  

Visible Fields


name: enabled, type: Bool, default: TRUE

Enables the light.

Render source

name: renderSource, type: Bool, default: FALSE

Renders the light in the scene (only for debugging).


name: color, type: Color, default: 1 1 1

The color of the light.


name: intensity, type: Float, default: 5, minimum: 0, maximum: 20

The intensity of the light.


name: width, type: Float, default: 0.5, minimum: 0.01, maximum: 5

The diameter of the disc (relative to the bounding box of the volume).


name: height, type: Float, default: 0.5, minimum: 0.01, maximum: 5

The height of the rectangle (relative to the bounding box of the volume)


name: theta, type: Float, default: 180

The spherical coordinate theta.


name: phi, type: Float, default: 45

The spherical coordinate phi.


name: distance, type: Float, default: 3.5, minimum: 0, maximum: 10

The distance of the light to the bounding box of the scene, relative to the bounding box diameter.

Attach light to camera

name: attachToCamera, type: Bool, default: FALSE

Attaches the light to the camera space instead of world space.


name: position, type: Vector3, default: 0 0 0

The position of the light (world or camera space), when Mode is PositionAndOrientation.


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

The orientation of the light (world or camera space), when Mode is PositionAndDirection.


name: type, type: Enum, default: AreaLight_Rectangle

Shape of the light.


Title Name Description
Disc AreaLight_Disc Disc
Rectangle AreaLight_Rectangle Rectangle


name: mode, type: Enum, default: DistanceAndAngles

Selects the positioning mode.


Title Name Description
Position And Orientation PositionAndOrientation Light is positioned via position and orientation, in world or camera space depending on Attach light to camera.
Distance And Angles DistanceAndAngles Light is positioned around bounding box of the scene in given distance and with given spherical coordinates (angles).

Scale Mode

name: scaleMode, type: Enum, default: ScaleToBoundingSphere

The scaling of the light parameters.


Title Name Description
Scale To Bounding Sphere ScaleToBoundingSphere Scale light intensity and distance by the bounding sphere diameter.
Scaling Off ScalingOff No scaling.