Updated glossary definitions for look direction, camera coordinate system,...

  <def>Sample</def>                     = 1.0

  <def>Line</def>                       = 1.0

  <def link="Digital Number">PixelValue</def>                 = 0.0607816

  <def link="Right Ascension">RightAscension</def>             = 65.749350916052

  <def>Declination</def>                = -18.390093214966

  <def link="Planetocentric Latitude">PlanetocentricLatitude</def>     = 34.444196777763

  <def link="Planetographic Latitude">PlanetographicLatitude</def>     = 34.760399604837

  <def link="Positive East Longitude">PositiveEastLongitude</def>      = 223.84999971299

  <def link="Positive West Longitude">PositiveWestLongitude</def>      = 136.15000028701

  <def link="Right Ascension">RightAscension</def>             = 65.749350916052 &lt;DEGREE&gt;

  <def>Declination</def>                = -18.390093214966 &lt;DEGREE&gt;

  <def link="Planetocentric Latitude">PlanetocentricLatitude</def>     = 34.444196777763 &lt;DEGREE&gt;

  <def link="Planetographic Latitude">PlanetographicLatitude</def>     = 34.760399604837 &lt;DEGREE&gt;

  <def link="Positive East Longitude">PositiveEastLongitude</def>      = 223.84999971299 &lt;DEGREE&gt;

  <def link="Positive West Longitude">PositiveWestLongitude</def>      = 136.15000028701 &lt;DEGREE&gt;

  <def link="Body Fixed Coordinate">BodyFixedCoordinate</def>        = (-2015.9595225544, -1936.6155808127, 1917.2574858384) &lt;km&gt;

  <def link="Local Radius">LocalRadius</def>                = 3389756.4767145 &lt;m&gt;

  <def link="Sample Resolution">SampleResolution</def>           = 536.05556350077 &lt;m/pixel&gt;

  <def link="Oblique Sample Resolution">ObliqueSampleResolution</def>    = 605.06647637166 &lt;m/pixel&gt;

  # Spacecraft Information

  SpacecraftPosition         = (-2025.6211429076, -2130.1417975758, 2009.318879871) <km>

  <def link="Spacecraft Azimuth">SpacecraftAzimuth</def>          = 0.006855593033889

  <def link="Spacecraft Azimuth">SpacecraftAzimuth</def>          = 0.006855593033889 &lt;DEGREE&gt;

  <def link="Slant Distance">SlantDistance</def>              = 214.52515878961 &lt;km&gt;

  <def link="Target Center Distance">TargetCenterDistance</def>       = 3560.6189705415 &lt;km&gt;

  <def link="SubSpacecraft Latitude">SubSpacecraftLatitude</def>      = 34.354896748841

  <def link="SubSpacecraft Longitude">SubSpacecraftLongitude</def>     = 226.44072947174

  <def link="SubSpacecraft Latitude">SubSpacecraftLatitude</def>      = 34.354896748841 &lt;DEGREE&gt;

  <def link="SubSpacecraft Longitude">SubSpacecraftLongitude</def>     = 226.44072947174 &lt;DEGREE&gt;

  SpacecraftAltitude         = 170.83335389965 <km>

  <def link="Off Nadir Angle">OffNadirAngle</def>              = 36.149255932304

  <def link="SubSpacecraft Ground Azimuth">SubSpacecraftGroundAzimuth</def> = 91.64525294858

  <def link="Off Nadir Angle">OffNadirAngle</def>              = 36.149255932304 &lt;DEGREE&gt;

  <def link="SubSpacecraft Ground Azimuth">SubSpacecraftGroundAzimuth</def> = 91.64525294858 &lt;DEGREE&gt;

  # Sun Information

  SunPosition                = (-177337948.13839, 112957442.69098, -33704752.205292) <km>

  <def link="Sun Azimuth">SubSolarAzimuth</def>            = 172.30460990873

  <def link="Sun Azimuth">SubSolarAzimuth</def>            = 172.30460990873 &lt;DEGREE&gt;

  SolarDistance             = 1.4234246174889 <AU>

  <def link="SubSolar Latitude">SubSolarLatitude</def>           = -9.1071705738361

  <def link="SubSolar Longitude">SubSolarLongitude</def>          = 147.50443340123

  <def link="Subsolar Ground Azimuth">SubSolarGroundAzimuth</def>      = 254.69139701227

  <def link="SubSolar Latitude">SubSolarLatitude</def>           = -9.1071705738361 &lt;DEGREE&gt;

  <def link="SubSolar Longitude">SubSolarLongitude</def>          = 147.50443340123 &lt;DEGREE&gt;

  <def link="Subsolar Ground Azimuth">SubSolarGroundAzimuth</def>      = 254.69139701227 &lt;DEGREE&gt;

  # Illumination and Other

  <def link="Phase Angle">Phase</def>                      = 120.59515694473

  <def link="Incidence Angle">Incidence</def>                  = 84.106289446623

  <def link="Emission Angle">Emission</def>                   = 38.288719431206

  <def link="North Azimuth">NorthAzimuth</def>               = 261.46910874636

  <def link="Phase Angle">Phase</def>                      = 120.59515694473 &lt;DEGREE&gt;

  <def link="Incidence Angle">Incidence</def>                  = 84.106289446623 &lt;DEGREE&gt;

  <def link="Emission Angle">Emission</def>                   = 38.288719431206 &lt;DEGREE&gt;

  <def link="North Azimuth">NorthAzimuth</def>               = 261.46910874636 &lt;DEGREE&gt;

  # Time

  <def link="Ephemeris Time">EphemerisTime</def>              = -69382819.160519 &lt;seconds&gt;

  <def>UTC</def>                        = 1997-10-20T10:58:37.6570806

  LocalSolarTime             = 17.089704420784 <hour>

  <def link="Solar Longitude">SolarLongitude</def>             = 201.83159041209

  <def link="Solar Longitude">SolarLongitude</def>             = 201.83159041209 &lt;DEGREE&gt;

  Error                      = NULL

End_Group

    </pre>

            equator.

          </definition>

          <definition name="Look Direction">

            The look direction is the direction that the instrument is pointing. 

            In ISIS, it is represented as a mathematical unit vector. 

            For images that have a body (i.e. not star fields), 

            this vector is parallel to the line from the sensor to the observed point 

            on the surface of the target. The look direction can be represented in 

            any of several coordinate systems, including: <a href="#Body-FixedCoordinateSystem">

            Body-fixed coordinate system</a>, <a href="#CameraCoordinateSystem">Camera coordinate system</a>,

            <a href="#J2000CoordinateSystem">J2000 coordinate system</a>.

          </definition>

          <definition name="Body-Fixed Coordinate System">

            A body-fixed coordinate system is used to determine positions and directions 

            of objects and vectors with respect to a target body. The origin is at the 

            center of mass for the target and the axes rotate and move through space with 

            the body. These systems are non-inertial, meaning the velocity of the origin 

            is non-constant. Many body-fixed coordinate systems, or reference frames, are 

            defined in NAIF PCK files.

          </definition>

          <definition name="Camera Coordinate System">

            A camera coordinate system is used to determine positions and directions 

            of objects and vectors with respect to a sensor (i.e. camera). The origin

            is at the center of the sensor and the axes rotate and move through space 

            with the sensor. These systems are non-inertial, meaning the velocity of the origin 

            is non-constant. The location of the center of a spacecraft and its instruments 

            at a given time are defined in NAIF SPK files. Generally, one or more frames are 

            associated with a particular instrument.

          </definition>

          <definition name="J2000 Coordinate System">

            The J2000 coordinate system (also known as EME2000) is based on the earth 

            mean equator and dynamical equinox at midnight January 1, 2000. The origin 

            is at the solar system barycenter. This system is inertial, since it does not 

            rotate with respect to stars and the origin is not accelerating (i.e it has a 

            constant velocity). This coordinate system is the root reference for NAIF's SPICE 

            files and software.

          </definition>

        </definitions>

      </body>

      Changed Brief description to "ISIS and Image Processing Terms 

      and Definitions" and fixed misspellings.

    </change>

    <change name="Curtis Rose" date="2016-08-05">

      Added definitions for Look Direction, Body-Fixed Coordinate System, Camera

      Coordinate System and J2000 Coordinate System.

      The coordinate systems are highly related to the look direction so they are also

      linked in that location.

    </change>

  </history>

</documentation>