EM 1110-2-2907
1 October 2003
Nonsystematic distortion
Geometric irregularities on images that are not constant and cannot be
predicted from the characteristics of the imaging system.
Normal color film
Film in which the colors are essentially true representations of the
colors of the terrain.
NSSDC
National Space Science Data Center.
O
Oasis
A spot in a desert made fertile by water, which normally originates as
Oblique photograph
Photograph acquired with the camera intentionally directed at some
angle between horizontal and vertical orientations.
OMS
Orbital maneuvering system.
ONC--Operational
The ONC series covers most of the world landmass areas at
Navigation Chart
1:1,000,000 scale. At this scale it takes 62 charts to cover the
conterminous United States. Information on these charts includes cities
and landmarks, drainage, and relief (shown by shading and contours).
International and State boundaries are shown, but not county
Orbit
Path of a satellite around a body such as the earth, under the influence
of gravity.
Orthophotograph
A vertical aerial photograph from which the distortions due to varying
elevation, tilt, and surface topography have been removed, so that it
represents every object as if viewed directly from above.
Orthophotoscope
An optical-electronic device, which converts a normal vertical aerial
photograph to an orthophotograph.
Ortho-correction
Correction applied to satellite imagery to account for terrain-induced
distortion.
Overlap
Extent to which adjacent images or photographs cover the same
terrain, expressed as a percentage.
P
Panchromatic film
Black and white film that is sensitive to all visible wavelengths.
Parallax
Displacement of the position of a target in an image caused by a shift in
the observation system.
Parallax difference
The difference in the distance on overlapping vertical photographs
between two points, which represent two locations on the ground with
different elevations.
Parallel-polarized
Describes a radar pulse in which the polarization of the return is the
same as that of the transmission. Parallel-polarized images may be HH
(horizontal transmit, horizontal return) or VV (vertical transmit, vertical
return).
Pass
In digital filters, refers to the spatial frequency of data transmitted by the
filter. High-pass filters transmit high-frequency data; low-pass filters
transmit low-frequency data.
Passive microwaves
Radiation in the 1 mm to 1 m range emitted naturally by all materials
above absolute zero.
Passive remote sensing
Remote sensing of energy naturally reflected or radiated from the
terrain.
Path-and-row index
System for locating Landsat MSS and TM images.
Pattern
Regular repetition of tonal variations on an image or photograph.
Periodic line dropout
Defect on Landsat MSS or TM images in which no data are recorded
for every sixth or sixteenth scan line, causing a black line on the image.
Glossary-21
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