levpt Documentation

levpt - Generate geometric information for a point(s) in a cube
This program generates geometric information for a single sample/line
or lat/lon position or for multiple sample/line positions in a cube
or list of cube files.  The information listed includes the
following geometric parameters:

        Sample
        Line
	Latitude
	Longitude
	Sample Resolution (KM)
	Line Resolution (KM)
        Aspect Ratio
	Phase Angle              (only if ISIS_GEOMETRY group is complete)
	Incidence Angle          (only if ISIS_GEOMETRY group is complete)
	Emission Angle           (only if ISIS_GEOMETRY group is complete)
	North Azimuth Angle      (only if ISIS_GEOMETRY group is complete)
	Slant Distance (KM)      (only if ISIS_GEOMETRY group is complete)
	Local Solar Time         (only if ISIS_GEOMETRY group is complete)
	Solar Longitude          (only if ISIS_GEOMETRY group is complete)
        Intercept Point (KM)     (only if ISIS_GEOMETRY group is complete)
	Spacecraft Position (KM) (only if ISIS_GEOMETRY group is complete)
	Modified Julian Date     (only if ISIS_GEOMETRY group is complete)
	Spacecraft Event Time    (only if ISIS_GEOMETRY group is complete)
	Sun Azimuth              (only if ISIS_GEOMETRY group is complete)
	Limb Angle               (only if ISIS_GEOMETRY group is complete
	                          - not implemeted yet)

The North Azimuth Angle is the clock-wise angle from an imaginary
three o'clock axis with the origin at the center of the pixel.

The Slant Distance is the distance from the spacecraft to the point
of interest on the surface of the planet.

The Local Solar Time for a point on a body is based on the difference
between the planetocentric longitude of the point and the planetocentric
longitude of the Sun as seen from the center of the body.

The Solar Longitude is the planetocentric longitude of the sun as
seen from a point on a body. This value is used as a measure of
Martian seasons.

The Intercept Point is the point on the surface of the target where
the look vector intersects. This (x,y,z) point is in the body-fixed
rotating coordinate system.

The Spacecraft Position is the position of the spacecraft (x,y,z) in
body-fixed rotating coordinate system.

The Modified Julian Date is the Julian Date of the observation minus
2400000.5 such that MJD 0 occurs at midnight between the 16 and 17
November 1858 AD Gregorian.

The Spacecraft Event Time is the time of the observation in UTC
format (yyyy-mm-ddThh:mm:ss.sss).

The Sun Azimuth is the angle in degrees relative to 3 o'clock positive
clockwise at a point in the image to the direction of the sun at the
time the image was acquired. It tells you which direction the sun is
coming from in the image.

The Limb Angle is the angle in degrees from a point in the image to
the limb. This option is not implemented yet. The result will always
be 0.

The program can operate on a single cube using the FROM parameter, in
which case the information is output to the log file (i.e., print.prt)
and the terminal screen.

Or, a FROMLIST can be specified, in which case a list of cubes is
expected to be in the file and the information will be output in ascii
to the file specified by the TO parameter.

The format for TO file is one line for each cube which ran successfully,
where each line contains the following values separated by spaces:

        sample
        line
	latitude
	longitude
	sample resolution
	line resolution
        aspect ratio
	phase angle
	incidence angle
	emission angle
	north azimuth
	slant distance
	local solar time
	solar longitude
	intercept point
	spacecraft position
	modified julian date
	spacecraft event time
	sun azimuth
	limb angle - not implemented yet
	filename

In addition, a TOERR file can be generated which will contain a list of
cubes that failed.

The geometric information for a cube can be generated by using a DEM
as the source for the local radius of each projected point in the cube.
This is helpful if you need information about a level 1 cube based on
a DEM file.

Programmer: Debbie A. Cook, U.S.G.S., Flagstaff, AZ

Input cube file name
  (default extension is .cub)

OR

--

File containing a list of cubes

--

File containing a list of points

--

Type of points in PNTLIST
(LATLON,LINESAMP)

--

ASCII file to write information

--

List of unsuccessful cubes

--

Sample position in cube(s)

--

Line position in cube(s)

--

Sample/line increment in
cube(s)

OR

0,0

Latitude of position in cube(s)

--

Longitude of position in cube(s)

--

DEM file for radii source

--

ADDITIONAL NOTES:

Parm	Description
FROM	Input cube file name. If the file extension is omitted, then ".cub" will be assumed. You can't use FROMLIST if you use this parameter.
FROMLIST	A file containing a list of cubes which will all be processed. You can't use FROM if you use this parameter and you must specify TO.
PNTLIST	You can optionally specify a file containing a list of points in the image for which geometric information will be acquired. If you use PNTLIST, then the SAMP, LINE, INC, LAT, LON parameters will be ignored. If you use PNTLIST, then you must specify the type of data in the list using PNTTYPE. The list must contain a single comma-delimited lat,lon or line,sample pair per line.
PNTTYPE	If you are using PNTLIST, then you must specify the type of data contained in the list: LATLON or LINESAMP. This parameter is ignored if PNTLIST is not specified.
TO	A file which will contain the output information for the cube(s). This parameter must be specified when a FROMLIST is entered. Type help * to find out about the format of the TO file.
TOERR	A file which will contain the cubes in FROMLIST which failed.
SAMP	The sample position in the file(s) to describe. If SAMP, LINE, LAT, and LON are defaulted, the center of the image will be described.
LINE	The line position in the file(s) to describe. See SAMP for the default.
INC	If no sample/line or lat/lon are entered, then this parameter can be used to specify the sample/line increment to use if information is required for more than one point. If INC=(0,0) and no sample/line or lat/lon are entered, then information will be acquired for the center of the image only. If a sample/line or lat/lon is entered, then this parameter is ignored. If INC=(1,1), then information is generated for every point in the image. If INC=(10,10), then information is generated for every 10th sample and every 10th line in the image (starting at sample/line=1,1). If this option is used, then information will always be generated for the first/last sample in a line being computed and the first/last line for each sample being computed (regardless of whether the INC ends on the last sample/line).
LAT	The latitude position to describe. See SAMP for the default.
LON	The longitude position to describe. See LINE for the default.
DEM	Enter a level 2 file to be used as a source for the local radius for each projected point in a level 1 cube. The default is to project onto the ellipsoid defined by the radii in the targdef file.