User's Guide

CORNERS

Returns latitude and longitude coordinates for an AVHRR LAS image

Function:

The subcommand -FULL returns nine latitude and longitude coordinates (upper left, upper nadir, upper right, center left, center nadir, center right, lower left, lower nadir, and lower right) of an AVHRR LAS image. The number of lines, number of samples, and the direction of the pass are also returned. This information is relative to the original AVHRR pass even if the AVHRR LAS image has been windowed.

The subcommand -FOUR calculates and returns the four latitude and longitude corner coordinates (upper left, upper right, lower left, and lower right) of the image. These coordinates represent the latitude/longitude locations at the AVHRR image corners.

Parameters:

Subcommand -FULL:
The size of the image, direction of the pass, and nine latitude/longitude coordinates (upper left, upper nadir, upper right, center left, center nadir, center right, lower left, lower nadir, and lower right) are retrieved from the AVHRR LAS DDR. This information is then returned in the specified TAE name parameters.

IN
Input image. The name of the AVHRR LAS image for which coordinate information is to be returned.

ULLAT
Upper left latitude. The original AVHRR pass upper left latitude is retrieved from the AVHRR LAS DDR and returned in this parameter's real TAE variable.

ULLON
Upper left longitude. The original AVHRR pass upper left longitude is retrieved from the AVHRR LAS DDR and returned in this parameter's real TAE variable.

UNLAT
Upper nadir latitude. The original AVHRR pass upper nadir latitude is retrieved from the AVHRR LAS DDR and returned in this parameter's real TAE variable.

UNLON
Upper nadir longitude. The original AVHRR pass upper nadir longitude is retrieved from the AVHRR LAS DDR and returned in this parameter's real TAE variable.

URLAT
Upper right latitude. The original AVHRR pass upper right latitude is retrieved from the AVHRR LAS DDR and returned in this parameter's real TAE variable.

URLON
Upper right longitude. The original AVHRR pass upper right longitude is retrieved from the AVHRR LAS DDR and returned in this parameter's real TAE variable.

CLLAT
Center left latitude. The original AVHRR pass center left latitude is retrieved from the AVHRR LAS DDR and returned in this parameter's real TAE variable.

CLLON
Center left longitude. The original AVHRR pass center left longitude is retrieved from the AVHRR LAS DDR and returned in this parameter's real TAE variable.

CNLAT
Center nadir latitude. The original AVHRR pass center nadir latitude is retrieved from the AVHRR LAS DDR and returned in this parameter's real TAE variable.

CNLON
Center nadir longitude. The original AVHRR pass center nadir longitude is retrieved from the AVHRR LAS DDR and returned in this parameter's real TAE variable.

CRLAT
Center right latitude. The original AVHRR pass center right latitude is retrieved from the AVHRR LAS DDR and returned in this parameter's real TAE variable.

CRLON
Center right longitude. The original AVHRR pass center right longitude is retrieved from the AVHRR LAS DDR and returned in this parameter's real TAE variable.

LLLAT
Lower left latitude. The original AVHRR pass lower left latitude is retrieved from the AVHRR LAS DDR and returned in this parameter's real TAE variable.

LLLON
Lower left longitude. The original AVHRR pass lower left longitude is retrieved from the AVHRR LAS DDR and returned in this parameter's real TAE variable.

LNLAT
Lower nadir latitude. The original AVHRR pass lower nadir latitude is retrieved from the AVHRR LAS DDR and returned in this parameter's real TAE variable.

LNLON
Lower nadir longitude. The original AVHRR pass lower nadir longitude is retrieved from the AVHRR LAS DDR and returned in this parameter's real TAE variable.

LRLAT
Lower right latitude. The original AVHRR pass lower right latitude is retrieved from the AVHRR LAS DDR and returned in this parameter's real TAE variable.

LRLON
Lower right longitude. The original AVHRR pass lower right longitude is retrieved from the AVHRR LAS DDR and returned in this parameter's real TAE variable.

NLINES
Number of lines. The number of lines in the original AVHRR pass is retrieved from the AVHRR LAS DDR and returned in this parameter's integer TAE variable.

NSAMPS
Number of samples. The number of samples in the original AVHRR pass is retrieved from the AVHRR LAS DDR and returned in this parameter's integer TAE variable.

ADFLAG
Ascending/descending direction flag. The direction of the original AVHRR pass is retrieved from the AVHRR LAS DDR and returned in this parameter's integer TAE variable. Valid return values are:

  =  1:  Ascending pass
  = -1:  Descending pass
Subcommand -FOUR:
The four corner latitude/longitude coordinates (upper left, upper right, lower left, and lower right) are calculated for the AVHRR LAS image and returned in the specified TAE name parameters.

IN
Input image. The name of the AVHRR LAS image for which coordinate information is to be returned.

ULLAT
Upper left latitude. The upper left latitude is calculated for the AVHRR LAS image and returned in this parameter's real TAE variable.

ULLON
Upper left longitude. The upper left longitude is calculated for the AVHRR LAS image and returned in this parameter's real TAE variable.

URLAT
Upper right latitude. The upper right latitude is calculated for the AVHRR LAS image and returned in this parameter's real TAE variable.

URLON
Upper right longitude. The upper right longitude is calculated for the AVHRR LAS image and returned in this parameter's real TAE variable.

LLLAT
Lower left latitude. The lower left latitude is calculated for the AVHRR LAS image and returned in this parameter's real TAE variable.

LLLON
Lower left longitude. The lower left longitude is calculated for the AVHRR LAS image and returned in this parameter's real TAE variable.

LRLAT
Lower right latitude. The lower right latitude is calculated for the AVHRR LAS image and returned in this parameter's real TAE variable.

LRLON
Lower right longitude. The lower right longitude is calculated for the AVHRR LAS image and returned in this parameter's real TAE variable.

Examples:

  1. LAS> corners-full in=wholus ullat=uly ullon=ulx unlat=uny unlon=unx urlat=ury urlon=urx cllat=cly cllon=clx cnlat=cny cnlon=cnx crlat=cry crlon=crx lllat=lly lllon=llx lnlat=lny lnlon=lnx lrlat=lry lrlon=lrx nlines=nl nsamps=ns adflag=pass

    The nine latitude/longitude coordinates are retrieved from AVHRR LAS DDR and returned in the appropriate TAE variables. The number of lines, number of samples, and direction of the original AVHRR pass are also returned in the appropriate TAE variables.

  2. LAS> corners-four in=alaska ullat=uly ullon=ulx urlat=ury urlon=urx lllat=lly lllon=llx lrlat=lry lrlon=lrx

    Only the four latitude/longitude corner coordinates for the AVHRR LAS image ALASKA are calculated and returned in the appropriate TAE variables.

Description/Algorithm:

The -FULL subcommand retrieves the size of the image, direction of the pass, and nine latitude/longitude coordinates from the AVHRR LAS DDR. This information is returned in the specified TAE name parameters.

The -FOUR subcommand calculates the four corner latitude/longitude coordinates for the AVHRR LAS image. These coordinates are returned in the specified TAE name parameters.

Nonfatal Error Message:

    None.

Fatal Error Messages:

  1. [corners-fatal] Fatal error encountered

    A fatal error was encountered during processing. The error message displayed immediately preceding this message is the specific error encountered.

User Notes:

  1. The -FULL subcommand retrieves the size of the image, the direction of the pass, and the nine latitude/longitude coordinates from the original AVHRR pass, even if the AVHRR LAS image was windowed.

  2. The -FOUR subcommand calculates the four corner coordinates for the AVHRR LAS. If the AVHRR LAS image is windowed, these coordinates represent the latitude/longitude locations at the window corners.