Rayfront User Manual

Object Settings

Each object can be treated in one of four different ways in a simulation (plug-in modules may add more possibilities).

Use Plain Object

This option is the default and means that the object will see no special treatment. The modifiers assigned in the object list will apply directly.

Precompute Object Surfaces as Virtual Planes

This option is normally used for transparent surfaces to give better results in complex simulations. The surfaces will be looked at in a preliminary simulation stage, in order to determine the amount and the distribution of the light that leaves each surface from it's front side. A luminous replacement surface with this distribution is then inserted into the scene. If this is done eg. for the glass surfaces in a window, then the final simulation will not need to calculate any rays outside the room to find the light sources there, but can use the precalculated values instead, except when the window is viewed directly in an image.

This treatment is not appropriate for very large sources, or for sources with highly directional distributions.

Create Sources as:
If the virtual sources are created with the illum material type, then they will be invisible, and the image will show the actual geometry behind when viewed directly. If they are created with light, then they will be visible as luminous surfaces.

# of Sample Directions:
Set the number of direction samples per projected steradian to integer. The number of directions calculated for each surface will be approximately this number multiplied by pi for polygons and rings, and by 4pi for spheres. If set to zero, then a diffuse source is assumed and no distribution is created.

Samples per Direction:
Set the number of ray samples per direction to this value. This affects the accuracy of the distribution value for each direction as well as the computation time.

Ignore Sources Below (W/sr m2):
Do not produce a secondary source for a surface if its average brightness (radiance) is less than this value.

Color Information:
If Distribution is selected, then the precalculations will be made with full color depth, trippling the time and storage requirements. For Average, the full color values are calculated, but only the average is stored for each surface. With None, color is ignored in the precalculations.

Replace Markers in Object

This option replaces triangular markers in the object with a scene file or octree, as selected. The replacement files are made available by placing them in the "parts" subdirectory of the project directory. The transformation to locate the replacement for each marker is determined by the marker's location and orientation.

A marker should be a right angled triangle pointing like a half-arrow in the direction of the transformed x-axis. The longest side is the hypoteneuse, the second longest side is the x-axis, and the third longest side indicates the direction of the y-axis. Any additional sides will be ignored (ie. a quadrilateral may be used instead of a triangle if the extra side is small). The z-axis is determined by the cross product of the x and y axes, and the origin is the common vertex between x and y

This option should not be used with objects that contain other types of geometry data than triangular polygons.

Substitute by:
The scene or octree file that should be used to replace the triangular markers.

Scale by:
If non-zero, then the replacements will be scaled by this value multiplied with the length of the x-axis length of each marker triangle.

Replace Markers in Object by Luminaire Definition

The replacement of markers in objects by luminaire definitions is a special case of the mechanism as described above. Luminaire descriptions must first be imported from IESNA, Eulumdat, or CIBSE TM14 format files from the main dialog. The size of the markers is always ignored here and the luminaire definitions are inserted unscaled.

Luminaire:
Select a previously imported luminaire definition.

Note:
Luminaire definitions always have their main output axis in negative Z direction. This means that if a marker triangle is oriented such that the Z-axis of its coordinate system points up, then the luminaire will point down. In most cases, this is the desired effect, but special attention must be payed to luminaires that are intended to point into other directions.

Example:

The following shows the result of all the above settings in the object list:

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