PDS_VERSION_ID = PDS3
LABEL_REVISION_NOTE = "2019-04-05, V. DELLA CORTE"
RECORD_TYPE = STREAM
OBJECT = DATA_SET_MAP_PROJECTION
DATA_SET_ID = "RO-C-GIA-5-67P-DUST-MAPS-V1.0"
OBJECT = DATA_SET_MAP_PROJECTION_INFO
MAP_PROJECTION_TYPE = "SIMPLE CYLINDRICAL"
MAP_PROJECTION_DESC = "
In the simple cylindrical projection [SNYDER1987], parallels
of latitude and meridians of longitude are straight lines that
are perpendicular to one another.
This map projection is obtained from the Latitudinal coordinates
obtained transforming rectangular coordinates of the 67P/C-G CSO
reference frame. The CSO reference frame is defined as follows:
- The position of the sun relative to the body is the primary
vector: the X axis points from the body to the sun.
- The inertially referenced velocity of the sun relative to the
body is the secondary vector: the Y axis is the component of
this velocity vector orthogonal to the X axis.
- The Z axis is X cross Y, completing the right-handed reference
frame.
- All vectors are geometric: no aberration corrections are used.
For the transformation to Latitude and Longitude the X axis is
considered as the prime meridian.
The map is evaluated at a reference distance of 15 km.
The transformation from latitude and longitude (LAT, LON) in
degrees to LINE and SAMPLE is given by the following equations.
Longitude increases from west to east.
The transformation from latitude and longitude (LAT, LON) in
degrees to LINE and SAMPLE indices is given here by the following
equations.
Longitude increases from west to east and is non-negative.
SAMPLE = INT(SAMPLE_PROJECTION_OFFSET +
RES * (LON - CENTER_LONGITUDE)) + 1
LINE = INT(LINE_PROJECTION_OFFSET - RES * (LAT - CENTER_LATITUDE)) + 1
where:
LAT and LON
are the latitude and longitude of a given spot on the spherical
surface where measures are rescaled and reported in the AXIS keyword
Of the Label for each map
LINE_PROJECTION_OFFSET
is the line number on which the map projection origin
occurs; i.e., the line number that corresponds to the center
latitude.
SAMPLE_PROJECTION_OFFSET
is the sample number on which the map projection origin
occurs; i.e., the sample number that corresponds to the center
longitude.
CENTER_LONGITUDE, CENTER_LATITUDE
are the longitude and latitude chosen as the origin of the
map projection.
RES (MAP_RESOLUTION)
is the number of pixels per degree at the projection origin.
Values for LINE_PROJECTION_OFFSET, SAMPLE_PROJECTION_OFFSET,
CENTER_LONGITUDE, CENTER_LATITUDE, and MAP_RESOLUTION are found
in the IMAGE_MAP_PROJECTION object in an image's PDS label.
In the above definitions, a pixel is assumed to cover an area, and
the integral values of LINE and SAMPLE are assumed to correspond to
the center of the area. The pixel in the upper left corner is line 1,
sample 1. The latitude and longitude corresponding to the center of
pixel (1,1) are maximum latitude - 1/(RES*2) and westernmost longitude
+ 1/(RES*2). The top edge of pixel (1,1) has the maximum latitude in
the image. The left edge of pixel (1,1) has westernmost longitude
in the image."
ROTATIONAL_ELEMENT_DESC = "See [PREUSKERETAL2015]."
OBJECT = DS_MAP_PROJECTION_REF_INFO
REFERENCE_KEY_ID = "PREUSKERETAL2015"
END_OBJECT = DS_MAP_PROJECTION_REF_INFO
OBJECT = DS_MAP_PROJECTION_REF_INFO
REFERENCE_KEY_ID = "SNYDER1987"
END_OBJECT = DS_MAP_PROJECTION_REF_INFO
OBJECT = DS_MAP_PROJECTION_REF_INFO
REFERENCE_KEY_ID = "SEIDELMANNETAL2002"
END_OBJECT = DS_MAP_PROJECTION_REF_INFO
END_OBJECT = DATA_SET_MAP_PROJECTION_INFO
END_OBJECT = DATA_SET_MAP_PROJECTION
END