2011

not preserve the shapes of objects. Parallel lines seemingly converge in the view. The program
has perspective view settings for VPORTS table entries as well as viewport objects.
photometric lights Photometric lights are physically-correct lights. Physically correct lights
attenuate as the square of the distance. Photometry is the science of measurement of visible
light in terms of its perceived brightness.
photon map A technique to generate the indirect illumination effects of global illumination
used by the renderer. When it calculates indirect illumination, the renderer traces photons
emitted from a light. The photon is traced through the model, being reflected or transmitted
by objects, until it strikes a diffuse surface. When it strikes a surface, the photon is stored
in the photon map.
photorealistic rendering Rendering that resembles a photograph.
pick button The button on a pointing device that is used to select objects or specify points
on the screen. For example, on a two-button mouse, it is the left button by default.
pick points Clicking and acquiring a point on an object in the drawing.
pick-first The selection of objects before an action macro or command is issued.
pick-first set A selection set of objects that are selected prior to the execution of an action
macro or a command. See also pre-selection set.
plan view A view orientation from a point on the positive Z axis toward the origin (0,0,0).
(PLAN)
planar face A flat face that can be located anywhere in 3D space.
planar projection Mapping of objects or images onto a plane.
planar surface A flat surface that can be located anywhere in 3D space. (PLANESURF)
playback The process of executing the actions stored in a previously recorded action macro.
pline See polyline.
2666 | Chapter 52 Glossary