2011

Photon Renders the effect of a photon map. This requires that a photon map
be present. If no photon map is present, the Photon rendering looks just like
the nondiagnostic rendering of the scene: the renderer first renders the shaded
scene, then replaces it with the pseudocolor image.
■ Density. Renders the photon map as it is projected into the scene. High
density is displayed in red, and lower values render in increasingly cooler
colors.
■ Irradiance. Similar to the Density rendering, but shades the photons based
on their irradiance. The maximum irradiance is rendered in red, and lower
values render in increasingly cooler colors.
BSP Renders a visualization of the parameters used by the tree in the BSP
ray-trace acceleration method. If a message from the renderer reports
excessively large depth or size values, or if rendering seems unusually slow,
this can help you locate the problem.
■ Depth. Shows the depth of the tree, with top faces in bright red, and
increasingly deep faces in increasingly cool colors.
■ Size. Shows the size of leaves in the tree, with differently sized leaves
indicated by different colors.
Processing
Tile Size Determines the tile size for rendering. To render the scene, the image
is subdivided into tiles. The smaller the tile size, the more image updates are
generated during rendering. When the tile size is reduced, the number of
image updates increases, meaning that a rendering take longer to complete.
If the tile size is increased, fewer image updates occur and the rendering takes
less time to complete.
Tile Order Specifies the method used (render order) for tiles as an image is
rendered. You can choose a method based on how you prefer to see the image
appear as it renders in the Render Window.
■ Hilbert. Next tile to be rendered is based on the cost of switching to the
next one.
■ Spiral. Tiles are rendered beginning at the center of the image, and spiral
outward.
■ Left to Right. Tiles are rendered in columns, from bottom to top, left to
right.
■ Right to Left. Tiles are rendered in columns, from bottom to top, right to
left.
1678 | Chapter 18 R Commands