CCSD3ZF0000100000001NJPL3IF0PDSX00000001
PDS_VERSION_ID = PDS3
RECORD_TYPE = FIXED_LENGTH
RECORD_BYTES = 80
SPACECRAFT_NAME = MAGELLAN
TARGET_NAME = VENUS
OBJECT = DATA_SET_MAP_PROJECTION
DATA_SET_ID = "MGN-V-RDRS-5-DIM-V1.0"
OBJECT = DATA_SET_MAP_PROJECTION_INFO
MAP_PROJECTION_TYPE = "SINUSOIDAL"
MAP_PROJECTION_DESC = "The FMAP (Magellan Full
Resolution Radar Mosaic) is presented in a Sinusoidal Equal-
Area map projection. In this projection, parallels of latitude
are straight lines, with constant distances between equal
latitude intervals. Lines of constant longitude on either side
of the projection meridian are curved since longitude
intervals decrease with the cosine of latitude to account for
their convergence toward the poles. This projection offers a
number of advantages for storing and managing global digital
data; in particular, it is computationally simple, and data
are stored in a compact form.
The Sinusoidal Equal-Area projection is characterized by a
projection longitude, which is the center meridian of the
projection, and a scale, which is given in units of pixels/
degree. A projection longitude is defined for each FMAP; all
tiles within the FMAP use the same projection longitude. The
center latitude for all FMAPs is the equator.
The transformation from latitude and longitude to line and
sample is given by the following equations:
line = INT(LINE_PROJECTION_OFFSET - lat*MAP_RESOLUTION + 1.0)
sample = INT(SAMPLE_PROJECTION_OFFSET - (lon -
CENTER_LONGITUDE)*MAP_RESOLUTION*cos(lat) + 1.0)
Note that integral values of line and sample correspond to the
center of a pixel. Lat and lon are the latitude and longitude
of a given spot on the surface.
LINE_PROJECTION_OFFSET is the line number minus one on which
the map projection origin occurs. The map projection origin
is the intersection of the equator and the projection longitude.
The value of LINE_PROJECTION_OFFSET is positive for images
starting north of the equator and is negative for images
starting south of the equator.
SAMPLE_PROJECTION_OFFSET is the nearest sample number to the
left of the projection longitude. The value of SAMPLE_
PROJECTION_OFFSET is positive for images starting to the west
of the projection longitude and is negative for images starting
to the east of the projection longitude.
CENTER_LONGITUDE is the value of the projection longitude,
which is the longitude that passes through the center of the
projection.
MAP_RESOLUTION is measured in pixels/degree. FMAP products can
have possible resolutions of 1408, 235, and 35.
There are four PDS parameters that specify the latitude and
longitude boundaries of an image. MAXIMUM_LATITUDE and
MINIMUM_LATITUDE specify the latitude boundaries of the image,
and EASTERNMOST_LONGITUDE and WESTERNMOST_LONGITUDE specify the
longitudinal boundaries of the map.
Definitions of other mapping parameters can be found in the
PDS Data dictionary."
ROTATIONAL_ELEMENT_DESC = "See DAVIESETAL1989."
OBJECT = DS_MAP_PROJECTION_REF_INFO
REFERENCE_KEY_ID = "DAVIESETAL1989"
END_OBJECT = DS_MAP_PROJECTION_REF_INFO
OBJECT = DS_MAP_PROJECTION_REF_INFO
REFERENCE_KEY_ID = "BATSON1987"
END_OBJECT = DS_MAP_PROJECTION_REF_INFO
OBJECT = DS_MAP_PROJECTION_REF_INFO
REFERENCE_KEY_ID = "EDWARDS1987"
END_OBJECT = DS_MAP_PROJECTION_REF_INFO
OBJECT = DS_MAP_PROJECTION_REF_INFO
REFERENCE_KEY_ID = "SNYDER1987"
END_OBJECT = DS_MAP_PROJECTION_REF_INFO
END_OBJECT = DATA_SET_MAP_PROJECTION_INFO
END_OBJECT = DATA_SET_MAP_PROJECTION
END