The RenderMan Interface - Paul Bourke

Convert an image in a standard picture file representing a latitude-longitude map
whose name is picturename into an environment map whose name is texturename.
The storage format of the texture file and the precision of stored texture channels are
implementation-dependent.
This image has longitude equal to 0 degrees at the left, and 360 degrees at the right.
The latitude at the bottom is -90 degrees and at the top is 90 degrees. The bottom
of the picture is at the south pole and the top the north pole. The direction in space
corresponding to each of the points on the image is given by:
x = cos(longitude) · cos(latitude)
y = sin(longitude) · cos(latitude)
z = sin(latitude)
Notice that latitude-longitude environment maps are sensitive to the handedness of
the coordinate system in which they will be accessed. Environment maps which
are intended to be accessed in a right-handed coordinate system will, if displayed,
appear as a mirror image of those intended to be accessed in a left-handed coordinate
system.
RIB BINDING
MakeLatLongEnvironment picturename texturename filter swidth twidth ...parameterlist...
The filter parameter should be one of ”box”, ”triangle”, ”catmull-rom”, ”b-spline”, ”gaussian”
and ”sinc”. These correspond to the predefined filter functions described with
RiPixelFilter.
EXAMPLE
MakeLatLongEnvironment ”long.pic” ”long.tx” ”catmull-rom” 3 3
SEE ALSO
RiMakeCubeFaceEnvironment, environment() in the Shading Language
RiMakeCubeFaceEnvironment ( char *px, char *nx, char *py, char *ny, char *pz, char *nz,
char *texturename, RtFloat fov, RtFilterFunc filterfunc,
RtFloat swidth, RtFloat twidth, ...parameterlist...)
Convert six images in standard picture files representing six viewing directions into
an environment map whose name is texturename. The image pz (nz) is the image as
viewed in the positive (negative) z direction. The remaining images are those viewed
along the positive and negative x and y directions. The storage format of the texture
file and the precision of stored texture channels are implementation-dependent.
Each image is normally produced by a rendering program by placing the eye at the
center of the environment (usually the origin) and generating a picture in each of the
six directions. These pictures are the projection of the environment onto a set of cube
faces. Each face is usually assumed to be unit distance from the eye point. Cube face
environment maps should be generated with the following orientations:
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