PDS_VERSION_ID                    = PDS3
RECORD_TYPE                       = STREAM

TARGET_NAME                       = RHEA
INSTRUMENT_HOST_NAME              = "CASSINI ORBITER"


OBJECT                            = DATA_SET_MAP_PROJECTION
  DATA_SET_ID                     = "CO-S-ISSNA/ISSWA-5-MIDR-V1.0"

  OBJECT                          = DATA_SET_MAP_PROJECTION_INFO
    MAP_PROJECTION_TYPE           = "SIMPLE CYLINDRICAL"
    MAP_PROJECTION_DESC           = "The global mosaics are presented
      in a simple cylindrical map projection. This projection 
      is neither equal-area nor conformal.  The meridians,and 
      parallels are equidistant straight lines, intersecting at 
      right angles.

      The transformation from latitude and longitude to line and
      sample is given by the following equations:

      line = INT(LINE_PROJECTION_OFFSET - lat*MAP_RESOLUTION)

      sample = INT(SAMPLE_PROJECTION_OFFSET + 
               (lon - CENTER_LONGITUDE)*MAP_RESOLUTION*cos(lat))

      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 and sample are assumed to
      be 1-based, rather than 0-based.

      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.

      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 ACTON1996"


    OBJECT                        = DS_MAP_PROJECTION_REF_INFO
      REFERENCE_KEY_ID            = "SNYDER1987"
    END_OBJECT                    = DS_MAP_PROJECTION_REF_INFO

  END_OBJECT                      = DATA_SET_MAP_PROJECTION_INFO


  OBJECT                        = DATA_SET_MAP_PROJECTION_INFO
    MAP_PROJECTION_TYPE           = "STEREOGRAPHIC"
    MAP_PROJECTION_DESC           = "The polar parts of the global
      mosaic (above +55 degrees or below -55 degrees) are presented 
      in a stereographic projection.  The stereographic projection 
      is a conformal, azimuthal projection where the central 
      meridian and a particular parallel (if shown) are straight
      lines.  This is a perspective projection for the sphere.  All 
      meridians on the polar aspect and the equator on the 
      equatorial aspect are straight lines.

      All other meridians and parallels are shown as arcs of 
      circles.  Directions from the center of the projection are 
      true.

      The transformation from latitude and longitude to line and
      sample is given by the following equations:

      line = INT(LINE_PROJECTION_OFFSET - lat*MAP_RESOLUTION)

      sample = INT(SAMPLE_PROJECTION_OFFSET + 
               (lon - CENTER_LONGITUDE)*MAP_RESOLUTION*cos(lat))

      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 and sample are 
      assumed to be 1-based, rather than 0-based.

      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.

      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 ACTON1996"

    OBJECT                        = DS_MAP_PROJECTION_REF_INFO
      REFERENCE_KEY_ID            = "SNYDER1987"
    END_OBJECT                    = DS_MAP_PROJECTION_REF_INFO

  END_OBJECT                      = DATA_SET_MAP_PROJECTION_INFO


  OBJECT                        = DATA_SET_MAP_PROJECTION_INFO
    MAP_PROJECTION_TYPE           = "MERCATOR"
    MAP_PROJECTION_DESC           = "The equatorial part of the 
      global mosaic (between -/+ 57 degrees latitude) is presented 
      in a mercator projection.  The mercator projection is a 
      conformal, cylindrical projection where meridians are equally
      spaced straight lines. Parallels are unequally spaced straight
      lines, closest near the equator, cutting meridians at right
      angles.  The scale is true along the equator, or along two 
      parallels equidistant from the equator.  Rhumb lines 
      (loxodromes) are straight lines.  Poles are at infinity with
      great distortion of area in polar regions.

      The transformation from latitude and longitude to line and
      sample is given by the following equations:

      line = INT(LINE_PROJECTION_OFFSET - lat*MAP_RESOLUTION)

      sample = INT(SAMPLE_PROJECTION_OFFSET + 
               (lon - CENTER_LONGITUDE)*MAP_RESOLUTION*cos(lat))

      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 and sample are
      assumed to be 1-based, rather than 0-based.

      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.

      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 ACTON1996"

    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