User's Guide

MAKORB

Make a half orbit from the specified scenes

Function:

Make a half orbit from the specified scenes. The input scenes are stitched together using the time stamp codes. Any gaps between the scenes will be filled with zero filled lines. When two or more scenes overlap an area, any dropped lines in one scene will be replaced by a valid line from the other scene, if available. The input and output scenes are all AVHRR archive images.

Parameters:

INFILES
Input files. The name of the input AVHRR archive images to be stitched together to form a half orbit.

OUTFILE
Output file. The name of the output half orbit AVHRR archive image. If OUTFILE exists, it will be updated; if it does not exist, it will be created.

CEOSID
CEOS identifier. The alphanumeric code which identifies the station that stitched the raw AVHRR data. The first two characters of this identifier must be "KM". For example, "KM1" signifies orbits stitched at EDC, "KME" signifies orbits stitched at ESA.

Examples:

  1. LAS> makorb infiles=(ah11041792055820,ah11041792062501, al11041792061512) outfile = "orb18793" ceosid = "km1"

    The three input archive images will be stitched together using the time stamp codes from each input file to form an output half-orbital pass called "ORB18793." The CEOS ID of the pass will be "KM1" signifying that the scene was stitched at Eros Data Center.

  2. LAS> makorb infiles=(ah11041792060708) outfile = "orb18793" ceosid = "kme"

    If ORB18793 does not exist, it will be created as an exact copy of the input scene. If ORB18793 does exist, as from Example 1, the input scene AH11041792060708 will be stitched into the middle of it. The CEOS ID of the pass will be "KME" signifying that the scene was stitched at the European Space Agency (ESA).

Description/Algorithm:

If OUTFILE exists, it will be updated; if it does not exist, it will be created. The input scenes are sorted by increasing starting time. If the output scene exists but does not start before the input scenes, it is treated as an input scene to be copied into a new output scene.

The first input scene is copied to the output half-orbit scene. For all subsequent scenes, the input scene is copied into the output scene. Any overlap areas between two scenes are copied from the scene with the higher priority station in the priority;stations file in ADAPSTABLES. Dropped lines in overlap areas are replaced regardless of station priority if good data exists to replace it. Any gaps (areas in the half-orbit not covered by any of the scenes) are filled in with dropped lines.

If all scenes for a half-orbit are not available, the available ones may be stitched together, and the missing ones added in later.

Nonfatal Error Messages:

  1. [makorb-addrop] Cannot add any more dropped lines to output image

    There is no more room to store gaps in the scene's header. The dropped lines will still occur in the image even though they are not recorded in the header.

  2. [makorb-iopen] Error opening the input file <xxx>

    An error occurred trying to open the specified input scene. If it is an input scene, ensure the scene exists with read permission. Processing will continue on with the next input scene.

  3. [makorb-find] Error retrieving value of ADAPSTABLES

    The environment variable ADAPSTABLES was not set, so the station priority file could not be found. Processing will continue with equal priority given to each station in INFILES.

  4. [makorb-read] Error reading the station priority file

    An error occurred reading the station priority file in ADAPSTABLES. The station for the current scene will be given a zero priority.

Fatal Error Messages:

  1. [makorb-fatal] Fatal error encountered

    A fatal error was encountered during processing. Processing was terminated. The error message that is displayed immediately preceding this message is the specific error that was encountered. See User Note 2 for more information.

  2. [makorb-open] Error opening the output orbit file

    An error occurred trying to open the output scene. Check for write permission in the current working directory and on the output scene if it already exists.

  3. [makorb-renam] Error renaming the file <XXXXXX>

    MAKORB stitches the image(s) into a temporary file and then renames it into OUTFILE. Make certain that OUTFILE has been specified correctly (renaming across file systems may not work).

  4. [makorb-ceos] Invalid CEOS ID specified: <XXX>

    An invalid CEOS identifier was specified. The first two characters of this identifier must be "KM".

User Notes:

  1. If all scenes for a half-orbit are not available, the available ones may be stitched together. The missing ones may be added later.

  2. If a fatal error occurs while updating an existing half-orbit, OUTFILE may be corrupted (e.g., not match its header). If the header was not changed, the half-orbit scene may be recovered by running MAKORB with the corrupted half-orbit as the only INFILE and a new OUTFILE.

  3. If the processing message jumps back, this is because the program is backing up in the output scene to check an overlap area.

  4. The receiving station for each input scene is assigned a priority in the priority;stations file in ADAPSTABLES. The priorities are used in overlap areas between two scenes from different stations, the higher-priority station replacing the data from the lower-priority station.