This program converts a cube in camera coordinates to a map projection. It differs from the application "cam2map" in that it maps camera ra/dec (right acsension/declination) to map projection longitude/latitude. The program is useful for inflight geometric and optical distortion calibration of a camera when star images are collected. The input cube labels must have an Instrument Group and Kernels Group. That is, the program "spiceinit" should be run on the input cube prior to "skymap".

This program will pick appropriate defaults for most parameters. In particular for the MAP parameter, it will generate the following:

  Group = Mapping
    TargetName             = "Sky"
    EquatorialRadius       = 1.0
    PolarRadius            = 1.0

    LatitudeType           = Planetocentric
    LongitudeDirection     = PositiveEast
    LongitudeDomain        = 360

    MinimumLatitude        = Computed from the input camera cube or map file
    MaximumLatitude        = Computed from the input camera cube or map file
    MinimumLongitude       = Computed from the input camera cube or map file
    MaximumLongitude       = Computed from the input camera cube or map file
    CenterLongitude        = Computed from the input camera cube at the center of the image

    ProjectionName         = Projection name in the map file
    Scale                  = Computed from the input camera cube or map file
  EndGroup
    

Note that although the map projection group reflects latitude/longitude, those values are synomous with declination/right ascension.

Note that an important concept here is a Mapping group can come from any PVL file. You can use an existing map projected cube as input for the MAP user parameter. Because the cube has PVL labels and contains the Mapping group, you will essentially force the input camera cube to have the same mapping parameters or match the existing cube. Information about map projections and the Mapping group can be found in the Isis user documentation.

Finally, the user has the option to override the pixel resolution and the ground range (latitude/longitude). These changes can be facilitied through the parameters SCALE, SRA, ERA, SDEC, and EDEC.

In addition, skymap can be used to produce landed mosaics from rovers like MSL. This can be done using ALE to generate an ISD which can be attached to the cube via csminit. The user would then have to update the LongitudeDirection their map file to PositiveWest. This converts the projection from a right ascension/declination projection to an azimuth/elevation projection. Once that is done, the user would run their ISIS cube through skymap and see that the landed rover data would project relative to other images in the same image sequence.