PDS_VERSION_ID                    = PDS3

LABEL_REVISION_NOTE               = "
          2011-01-05 GEO:shs Original based on LOLA DSMAP.CAT
"
RECORD_TYPE                       = STREAM

OBJECT                            = DATA_SET_MAP_PROJECTION
 DATA_SET_ID                      = "LRO-L-DLRE-5-GDR-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 centered on the equator. The map
    resolution is constant throughout the image.

    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 = NINT(SAMPLE_PROJECTION_OFFSET + 
          RES * (LON - CENTER_LONGITUDE)) + 1

      LINE = NINT(LINE_PROJECTION_OFFSET - RES * (LAT - CENTER_LATITUDE)) + 1

    NINT is a Fortran intrinsic rounding function, identical to the C math.h 
    library function rint.  In the case of half-integer values, the NINT 
    function rounds to the nearest even whole number.

    The inverse transformation from the center of the pixel (SAMPLE,LINE) is

      LON = CENTER_LONGITUDE + (SAMPLE -SAMPLE_PROJECTION_OFFSET - 1) / RES

      LAT = CENTER_LATITUDE - (LINE - LINE_PROJECTION_OFFSET - 1) / RES

    Note that the offset of 1 is part of the equation, so that the result 
    of rounding the expression to the nearest whole number will produce a 
    value of (1,1) for a point whose longitude and latitude lie inside the 
    upper left-most pixel.

    For a map resolution of one degree per pixel, spanning longitudes from 
    0 to 360 degrees of longitude and from -90 to 90 degrees in latitude, 
    with CENTER_LONGITUDE = 180 degrees and CENTER_LATITUDE = 0 degrees, a 
    point lying in the open interval (0-1) degrees in longitude must lie in 
    sample 1. Thus, SAMPLE_PROJECTION_OFFSET = 179.5 so that for a point at 
    0.5 degree longitude, SAMPLE = NINT(179.5 + (0.5 - 180.)) + 1 will 
    result in a value of 1.

    The value 1 is added after rounding so that longitude 0 also is in 
    sample 1.  As a convention, longitude 360 lies within the last sample, 
    although this value should not occur in a standard conversion of angles 
    to degrees.

    Similarly, LINE_PROJECTION_OFFSET = 89.5 in this example.
    For a point lying midway between 89 and 90 degrees latitude,
    LINE = NINT(89.5 - (89.5 - 0.0)) + 1 will result in a value of 1.
    As a convention, latitude -90 lies within the last line.

    These equations refer to a digital array in which the positive 
    direction is to the right and down, and where:

    LAT and LON are the latitude and longitude of a given spot on the 
    surface in degrees.

    LINE_PROJECTION_OFFSET provides the line offset value of the map 
      projection origin position from the line and sample 1,1 (line and 
    sample 1,1 is considered the upper left corner of the digital array).

    SAMPLE_PROJECTION_OFFSET provides the sample offset value of the map 
       projection origin position from line and sample 1,1 (line and sample 
    1,1 is considered the upper left corner of the digital array). 

    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 [SEIDELMANNETAL2002]."

  OBJECT                          = DS_MAP_PROJECTION_REF_INFO
   REFERENCE_KEY_ID               = "SEIDELMANNETAL2002"
  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