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ISIS Documentation

ringspt

Outputs ring radius/longitude at line/sample or reverse for Cassini images of Saturn rings

This program requires the user supply a "level 1" cube. That is, a cube in raw camera geometry. The user must also enter one of the following coordinates: 
      line/sample
      ring radius/ring longitude
The program will then compute the other coordinates and various other spacecraft and instrument related information including but not limited to the north azimuth, solar azimuth, spacecraft azimuth, incidence angle, phase angle, emission angle, and resolution. The following is an example of the output given when campt is ran: 
Group = GroundPoint
  Filename                   = $ISISDATA/base/examples/ab102401.cub
  Sample                     = 1.0
  Line                       = 1.0
  PixelValue     
l            = 0.0607816
  RightAscension             = 65.749350916052
  Declination                = -18.390093214966
  PlanetocentricLatitude     = 34.444196777763
  PlanetographicLatitude     = 34.760399604837
  PositiveEastLongitude      = 223.84999971299
  PositiveWestLongitude      = 136.15000028701
  BodyFixedCoordinate        = (-2015.9595225544, -1936.6155808127, 1917.2574858384) <km>
  LocalRadius                = 3389756.4767145 <m>
  SampleResolution           = 536.05556350077 <m>
  LineResolution             = 536.05556350077 <m>

  # Spacecraft Information
  SpacecraftPosition         = (-2025.6211429076, -2130.1417975758, 2009.318879871) <km>
  SpacecraftAzimuth          = 0.006855593033889
  SlantDistance              = 214.52515878961 <km>
  TargetCenterDistance       = 3560.6189705415 <km>
  SubSpacecraftLatitude      = 34.354896748841
  SubSpacecraftLongitude     = 226.44072947174
  SpacecraftAltitude         = 170.83335389965 <km>
  OffNadirAngle              = 36.149255932304
  SubSpacecraftGroundAzimuth = 91.64525294858

  # Sun Information
  SunPosition                = (-177337948.13839, 112957442.69098, -33704752.205292) <km>
  SubSolarAzimuth            = 172.30460990873
  SolarDistance              = 1.4234246174889 <AU>
  SubSolarLatitude           = -9.1071705738361
  SubSolarLongitude          = 147.50443340123
  SubSolarGroundAzimuth      = 254.69139701227

  # Illumination and Other
  Phase                      = 120.59515694473
  Incidence                  = 84.106289446623
  Emission                   = 38.288719431206
  NorthAzimuth               = 261.46910874636

  # Time
  EphemerisTime              = -69382819.160519 <seconds>
  UTC                        = 1997-10-20T10:58:37.6570806
  LocalSolarTime             = 17.089704420784 <hour>
  SolarLongitude             = 201.83159041209
End_Group

In the output, all positions are in body fixed coordinates. The SubSpacecraftLatitude and SubSpacecraftLongitude make up the subspacecraft point, which is the point on a body which lies directly beneath the spacecraft. The SubSolarLatitude and SubSolarLongitude make up the subsolar point, which is the point on a body's refernce surface where a line from the body center to the sun center intersects that surface. The NorthAzimuth, SpacecraftAzimuth, and SubSolarAzimuth are the values of the angle between a line from the image center to the relative point (North pole, SubSpacecraft Latitude/Longitude, SubSolar Latitude/Longitude respectively) and a reference line in the image plane. The reference line is a horizontal line from the image center to the middle right edge of the image. The angles increase in a clockwise direction. The LocalSolarTime is the time at the current longitude relative to the subsolar longitude, which has a time of 12 o'clock. The SolarLongitude is LSubS, or the seasonal angle.

Categories

History

Ken Edmundson2012-07-31 Original version copied from campt application
Jeannie Backer2013-03-12 Added appTests. Test coverage 79% scope, 91% line, 100% function covers all but CameraRingsPointInfo::GetPointInfo() with allowErrors=true.
Jeannie Backer2014-08-22 Updated truth data. References #1659.

Parameters

Files

Input cube with appropriate camera labels (Instrument and kernel groups)
Type cube
File Mode input
Filter *.cub

A text file in label format which will contain the results of this program. This file can be used in conjunction with the "getkey" program in order to pass the results to another program when developing scripts.
Type filename
File Mode output
Internal Default None

Format type for output file. Pvl format is default.
Type string
Default PVL
Option List:
Option Brief Description
PVL Pvl Format Output file will be in pvl format
FLAT FlatFile Format Output file will be a comma deliminated flatfile. This file format can easily be imported into excel.

If this option is selected, the output from the application will be appended to the file. If it is not selected, any information in the TO file will be overwritten.
Type boolean
Default TRUE

Position

This parameter is used to select the type of coordinate which will be used to compute the other two remaining coordinates.
Type string
Default IMAGE
Option List:
Option Brief Description
IMAGEInterprets the coordinate as sample/line This option interprets the coordinate as sample/line and will compute ring radius/longitude and x/y/z

Exclusions

  • RINGRADIUS
  • RINGLONGITUDE
GROUNDInterprets the coordinates as ring radius/longitude This option interprets the coordinate as ring radius/longitude and will compute sample/line and x/y/z

Exclusions

  • LINE
  • SAMPLE

This is the sample position used to compute infomration about the camera state at the pixel.
Type double
Internal Default Center sample

This is the line position used to compute infomration about the camera state at the pixel.
Type double
Internal Default Center line

This is the ring radius position in kilometers from the center of the target body to try to locate in the image.
Type double
Minimum 0.0 (inclusive)

This is the counterclockwise ring longitude position to try to locate in the camera image
Type double
Minimum 0.0 (inclusive)
Maximum 360.0 (inclusive)

When this is checked, sample/line values that are outside of the image (but close) will be extrapolated. For example, a sample of -0.5 would be valid. If this is not checked, a sample of -0.5 is not allowed.
Type boolean
Default true