User's Guide

RANDADD

Adds random points near a densified cutline

Function:

Adds random points near a densified cutline. The input coordinates are stored in an Image Based Information System (IBIS) graphics file. The output coordinates are also stored in an IBIS graphics file.

Parameters:

INFILE
Input IBIS graphics file from which to read the coordinates of the densified cutline.

OUTFILE
Output IBIS graphics file will contain the additional random points.

PNTINC(100)
Point increment used in CUTADD when the cutline was densified.

SEEDVAL(1)
Seed value controls the initial state of the random point generator.

SL(1)
Start line of the image to which the cutline pertains.

SS(1)
Start sample of the image to which the cutline pertains.

NL(10000)
Number of lines in the image to which the cutline pertains.

NS(10000)
Number of samples in the image to which the cutline pertains.

Example:

  1. LAS> randadd infile=denscut outfile=randcut pntinc=35 seedval=100 sl=1 ss=1 nl=8000 ns=8900

    Coordinates of the densified cutline are stored in the IBIS graphics file DENSCUT. These points are read in and random points are added near the densified cutline. The random points generated near the cutline are written to the IBIS graphics file RANDCUT. The point increment used by CUTADD should have been 35 for RANDADD to work properly. The extent of the image to be cut is 8000 lines by 8900 samples. The seed value used in generating the random points is initialized to 100.

Description/Algorithm:

RANDADD steps along the densified cutline and adds random points in the vicinity of the densified cutline. This is done in order to improve the characteristics of the triangulated network that is generated using these points. The overall result is a much better radiometric match in mosaiced images.

RANDADD actually adds random points throughout the image--with most of the points falling near the densified cutline. The density of the random points will decrease as you move away from the cutline. The process of adding points continues until random points have been added across the the entire image.

Nonfatal Error Message:

  1. [randadd-close] Error closing <XXXXX> file

    An error was encountered closing the specified file. The data may be valid.

Fatal Error Messages:

  1. [randadd-fatal] Fatal error encountered

    A fatal error was encountered during processing. The output IBIS graphics file may or may not be valid. The message that is displayed immediately preceding this message is the specific error that was encountered.

  2. [randadd-open] Error opening <XXXXX> file

    An error was encountered while trying to open the specified file.

  3. [randadd-read] Error reading input file

    An error was encountered while trying to read from the input IBIS graphics file.

  4. [randadd-write] Error writing output file

    An error was encountered while trying to write to the output IBIS graphics file.

User Notes:

  1. The point increment (PNTINC) specified must match the point increment used in CUTADD to densify the cutline in order for RANDADD to function as it is intended to.

  2. The SEEDVAL gives some user control over the distribution of the random points in the image. If the results of the radiometric matching are not acceptable, the user may change the SEEDVAL to obtain a different distribution of random points.