P
page layout
The process of selecting, sizing, and positioning multiple items to compose a page for printing.
PA
Phase Alternating Line. A video standard generally used by the rest of the world outside the United States and Canada that is not compatible with NTSC.
pan
To move over an area of an image that is larger than the screen (visible area), but is loaded to the display board.
panchromatic image
An image collected in the broad visual wavelength range but rendered in black and white. The term has historically referred to a black and white photograph of a color scene. Since the SPOT satellite 10-meter images are collected over this broad visual spectral band and are usually rendered in black and white, these images are called panchromatic.
pane
A resizable subarea of a window containing related options or components and set off from other areas of the window by separators. The Tab key moves the location box from pane to pane. The arrow keys move the location box from component to component within one pane.
panel
A work area in a window composed of basic controls such as an array of buttons and sliders.
parallelepiped classifier or decision rule
A simple form of automated computer interpretation slightly more complex than boxcar interpretation. For parallelepiped classification, the boundaries between classes need not be rectangular or parallel to the axes. A parallelepiped area representing the location of each material sought is prism-shaped in the 2-, 3-, or n-dimensional distribution of the available multivariable images. (See also: boxcar classifier)
parallel port or parallel interface
A physical connection between a computer and a peripheral device, such as a printer. A parallel port uses a connection that has more than eight wires. Eight of the wires simultaneously convey the eight bits in a byte of data, while the remaining lines control status information such as "send me more" and "stop sending." DOS currently allows the use of three different standard parallel ports, which are named LPT1, LPT2, and LPT3.
parallels
Circles on the earth's surface, or lines on a map that are perpendicular to the axis of the earth, and mark latitude north or south of the Equator.
parent object
An independent prime object in a project file related to some other prime object below it in the project file hierarchy. An object linked by HyperIndex to some other objects is the parent of those objects (referred to as its daughter objects). (See also: daughter object, HyperIndex, index area, link, stack.)
Paris classification
An unsupervised classification or clustering process developed by Dr. Jack Paris and documented in: Jack F. Paris and Helenann H. Kwong (1988) Photogrammetric Engineering and Remote Sensing 54(8):1187-1193. Characterization of Vegetation with Combined Thematic Mapper (TM) and Shuttle Imaging Radar (SIR-B) Image Data.
PAT
Point attribute table or polygon attribute table. A coverage can have either a point attribute table or a polygon attribute table, but not both. In addition to user defined allributes a PAT contains data on Area and perimeter of a (Values are 0 for points) an internal sequence number and feature identifier.
path
A DOS path is a description of the hierarchical chain of directories that define the logical location of a file. For example, the path C:\FONTS\VFONTS.REF is the complete path that describes the logical location of the VFONTS.REF file which is in the \FONTS directory on hard disk C. The backslash character (\) separates elements in a path. A Unix path is similar to a DOS path, but the concept of drives are not given letter designations; they are named like any directory. Hence, there are no colons in a Unix path.
pcARC/INFO
A vector-based Geographic Information System (GIS) developed and marketed by ESRI, Inc. Unlike the parent minicomputer-based ARC/INFO, pcARC/INFO presents a command-driven interface.
PCIPS
A raster-based microcomputer image processing system developed and distributed by IBM. This is a menu-oriented entry-level system that runs on standard color display cards such as CGA and EGA. PCIPS provides an inexpensive and easy-to-use introduction to image processing.
PC-8
An 8-bit (256-character) IBM super set of the 7-bit ASCII character encoding scheme that includes various symbols plus Latin characters with diacritics. Printers and other output devices do not deal with the upper 128 characters in a standard fashion. Thus, what looks like an "i" with two dots instead of one (ï, PC-8 character 139) on the screen may print as something completely different. PC-8 makes different assignments for codes 128-255 than does Latin-1, and thus is not a proper subset of Unicode or ISO 10646.
pecabyte, Pbyte, or PB
A unit of computer measurement for (approximately) 1,000,000,000,000,000 bytes, 1,000,000,000,000 kilobytes, 1,000,000,000 megabytes, 1,000,000 gigabytes, or 1000 terabytes. (See also: bit, byte, exabyte, gigabyte, kilobyte, megabyte, terabyte.)
pen
One type of pointing device (sometimes called a "stylus") used with an X-Y digitizing tablet. It has a pencil-like feel which makes it ideal for free-hand drawing. (See also: pointing device, puck)
pen plotter
An output device for line drawings that mechanically moves an ink pen over the drawing surface.
photogrammetry
Obtaining precise measurements from images.
photointerpretation
Analyzing, measuring, and categorizing chosen features from airphotos.
physiographic
Describing the characteristics of a site's physical geography.
pictograph
A pictorial sign or symbol, for instance, representing a person with a stick figure.
picture element or pixel
"The smallest element of an image that can be individually processed in a video display system" (Random House).
Pinyin
(literally, "spell sounds") The phonetic alphabet based on Latin letters adopted in the People's Republic of China in 1958 based on the Beijing/Mandarin version of spoken Chinese.
pixel or picture element
"The smallest element of an image that can be individually processed in a video display system" (Random House). The text and images on a computer display are created by combinations of individual dots (pixels). Different display hardware allows for more or fewer pixels on the screen, determining the display resolution that is possible. The more rows and columns of pixels, the finer the image detail that can be resolved.
pixel depth or color depth
The number of data bits each pixel represents. In 8-bit contexts, the pixel depth is 8, and each display pixel can be one of 256 possible colors or shades of gray. With a 24-bit raster (or with three coregistered 8-bit rasters) the pixel depth is 24, and 16,777,216 colors are possible.
planimeter
"An instrument for measuring mechanically the area of plane figures" (Random House).
planimetric map
A map designed to portray the horizontal positions of features; vertical information is specifically ignored.
point element
A single point defined by a set of coordinates in space, and one of the types of elements in a vector object. Point attributes include:
Point - in - Polygon
A topological overlay procedure which determines the spatial coincidence of point and polygons. Points are assigned the attributes of the polygons within which they fall.
Precision
It refers to the number of significant digits used to store numbers and in particular, coordinate value. Precision is important for feature representation, analysis and mapping. ARC/INFO supports single precision and double precision.
Pseudo node
A node where two and only two arcsintersect or a single arc that connects with itself.