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Earth Imaging Glossary
A,
B,
C,
D,
E,
F,
G,
H,
I,
J,
K,
L,
M,
N,
O,
P,
Q,
R,
S,
T,
U,
V,
W,
X,
Y,
Z
" P "
PARSE
To break down a sequence of letters or numbers into meaningful parts based on their location
in the character sequence. For example, the first three numbers in the GLIS access phone
number 6055946888 are the area code numbers that identify the phone number as a South
Dakota location.
PC WORK STATION
As defined by GLIS, a PC work station is a 80286 or greater AT micro computer running the
MS-DOS operating system version 3.0 or higher. The PC should have 640 kilobytes of
computer memory and have a VGA 16 color 4 bit graphics board and color monitor. To
allow connection with the GLIS server the PC work station should have a Hayes or Hayes
compatible modem and some type of PC communication package. The PC should also have
at least 1 megabyte of hard disk space for GLIS software and data files.
Optional GLIS PC work station requirements include a mouse, math co-processor, and dot
matrix or laser printer.
PERMAFROST
A permanently frozen layer at variable depth below the surface in frigid regions of a planet
(as Earth).
PHENOLOGY or PHENOLOGICAL
Refers to the rate and timing of natural events, such as the growth cycle of vegetation over a
growing. Land cover and vegetation types may often be distinguished from each other by
their characteristic spectral/temporal signature, as illustrated by a graph plotting NDVI values
against time through a growing season for several agricultural categories. The shape and
position of each curve defines that category's phenological characteristics.
PHYSIOGNOMIC
The aspect and character of an abstract entity.
PIXEL
An abbreviation of picture element. The minimum size area on the ground detectable by a
remote sensing device. The size varies depending on the type of sensor.
PLANCK'S
Early in the twentieth century, Max Planck recognized the discrete nature of radiant energy
exchanges and proposed the quantum theory of electromagnetic radiation. His experiments
showed that energy is transferred in short wave trains or bursts in which each burst carries
radiant energy, Q, proportional to the frequency, of the wave, so that: Q = hv where h = the
universal, or Planck's constant, with a value of 6.625 X 10 to the -34 joule second. (a joule, in
physics, is a unit of work equal to 10 million ergs.)
PLANIMETRIC
Two dimensional. The measurement of plane surfaces. A map representing only horizontal
features. Parts of a map that represent everything except relief.
PLDS--Pilot Land Data System
The PLDS is a data and information management system developed to support land science
research activities by archiving, retrieving, and transferring land data. The PLDS program,
sponsored by the Communication and Information Systems Office, Land Processes Branch
within the Office of Space Science and Applications of NASA, is managed by Goddard
Space Flight Center with active participants at Ames Research Center (ARC) and the Jet
Propulsion Laboratory (JPL).
PLSS--PUBLIC LAND SURVEY SYSTEM
The U.S. Public Land Survey System is the most widespread land ownership system in the
United States. Roads, fields and political boundaries all reflect the character of a square grid
system or more commonly the Township and Range System.
POES--Polar Orbiting Environmental Satellite
The POES system began in 1960 with the launch of TIROS-1. Later satellites in the
Improved TIROS Operational Satellite (ITOS) program were expanded to capture concurrent
multiple-channel data on a daily basis. Currently the Advanced TIROS-N satellites (renamed
NOAA-6, 7, 8, etc., after launch) offer 4 or 5 channel multispectral daily repetitive global
coverage.
PRECISION
Precision is a statistical measurement of repeatability that is usually expressed as a variance
or standard deviation, root mean square or RMS, of repeated measurements. These are
expressed as x,y coordinates of arcs, label points, and tics in either single or double precision
in ARC/INFO.
Single-precision coordinates have up to seven significant digits of precision. This allows for
a level of accuracy of approximately 10 meters for a region whose extent is 1,000,000 meters
across.
Double-precision coordinates have up to 15 significant digits; this allows for the precision
necessary to represent any desired map accuracy at a global scale.
PROFILE
One method of making Digital Elevation Models (DEMs) is commonly referred to as
profiling. In this technique a stereo pair of photographs is set up in a photogrammetric
instrument and referenced to the ground using ground control points. After this process is
completed the instrument automatically moves a computer cursor across the stereo model. As
the cursor is being driven across the model, the operator controls the motion of the cursor
while a recording device captures the elevation figures. Each swath across the stereo model is
called a profile.
PROJECTION
Orderly system of lines on a plane representing a corresponding system of imaginary lines on
an adopted terrestrial or celestial datum surface. Also, the mathematical concept of such a
system. For maps of the Earth, a projection consists of (1) a graticule of lines representing
parallels of latitude and meridians of longitude or (2) a grid.
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Initial content for this Glossary of terms has been graciously supplied by RADARSAT International - www.rsi.ca
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