User's Guide

GRIDSUB

Subtract two geometric mapping grids and create a plot file of the differences

Function:

Subtracts two geometric mapping grids and creates a plot file of the differences.

Parameters:

INGRID
Input grid files. The input geometric mapping grid files. The denser of the two is found and the other is subtracted from it. The output size (number of output image lines and samples) of both grids must match; however, the number of rows and columns in each may differ.

OUTFILE
Output file. The output plot file of grid differences.

NL
Number of lines. The number of lines in the input space image.

NS
Number of samples. The number of samples in the input space image.

PRINT(TERM)
Output destination. The output destination of the grid residuals report. The available output destinations are:


  = --:        No Report
  = TERM:      Terminal.  Output is sent to the user's
               terminal.
  = LP:        Line printer.  Output is sent to the
               printer defined by $PRINTER.
  = Filename:  User-supplied filename.  Output is sent
               to the user-supplied file with the
               extension "prt".

Example:

  1. LAS> gridsub ingrid=(first,second) outfile=grid.plot nl=3000 ns=3000 print=term

    The denser of "frist;grid" and "second;grid" is found and the other is subtracted from it. Residuals are calculated and are written to the "grid.plot;plot" file. A summary of the errors is printed to the user's terminal.

Description/Algorithm:

Parameters are received from TAE and all files are opened. Both geometric mapping grid files are read. GRIDSUB then determines which grid is denser (has more rows and columns) and subtracts the other from it. Residuals for each grid intersection are calculated and written to the plot file. A summary of the residuals and other statistics are reported to the user.

Nonfatal Error Message:

  1. [gridsub-warning] Nonfatal error encountered

    The error message displayed immediately preceding this message is the specific error that was encountered. Processing continues.

Fatal Error Message:

  1. [gridsub-fatal] Fatal error encountered

    The error message displayed immediately preceding this message is the specific error that was encountered. Processing is terminated.

  2. [gridsub-output] Output space does not match

    The number of lines and samples in the output space must be identical before grids can be subtracted.

  3. [gridsub-plotfile] Error opening the plot file

    An error occurred while attempting to open the plot file. Check the file name and directory protections.

  4. [gridsub-printfile] Error opening the print file

    An error occurred while attempting to open the print file. Check the file name and directory protections.

User Note:

  1. This function creates a plot file for use with GEOREG, a data visualization system developed with TAE+ and the Xt Toolkit.