ISIS Application Documentation

findgaps

Finds the gaps in a given Cube.

Overview

Parameters

Example 1

Description

This program finds gaps in the line direction of an image, and will report the gap information or expand the gap based on user parameters or default settings. Gaps are areas where the entire line consists of NULL pixel values or pixel values statistically below the threshold setting of the CORTOL parameter. This program ignores single line gaps.If the LOG parameter is specified, the starting and last line of each gap as well as the band number is recorded and placed into a log filename (.pvl, .txt) entered by the user. If the output cube or TO parameter is not specified, then the program only identifies the gaps.

The CORTOL parameter should be set to "0.0" to only identify an entire line of "NULL" pixels as a gap. If the CORTOL parameter is set to a value greater than "0.0," then the statistics of the current line are compared against the statistics of the previous line to determine if the line should be considered a gap. This option is useful if random lines are much brighter or darker than the adjacent lines.

History

Christopher Austin	2007-11-26	Original version
Steven Lambright	2008-05-12	Removed references to CubeInfo
Kimberly Oyama and Steven Lambright	2012-06-15	Added the option to nullify a gap and add a buffer of null lines above and below each gap and output these results to a cube. If no output cube is specified results will only be output to a log file (.pvl, .prt, or .txt) or vice versa. Neither output affects the other. Fixes #582.

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File Modified: 02/21/2025 21:48:35

Parameter Groups

Files

Name	Description
FROM	Input cube file
TO	Output cube file
LOG	The output file of the list of gaps (.pvl, .prt, or .txt).

Correlation Coefficient Tolerance

Name	Description
CORTOL	Correlation Tolerance

Buffer Size (Lines)

Name	Description
ABOVE	Number of nulled lines above gaps.
BELOW	Number of nulled lines below gaps

Files: FROM

Description

Input cube file to be checked for line gaps.

Type	cube
File Mode	input
Filter	*.cub

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Files: TO

Description

The resulting cube with a null buffer above and below each gap. Enter "TO=none" if you do not want to output a modified cube.

Type	cube
File Mode	output
Default	none
Filter	*.cub

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Files: LOG

Description

The output file to which all of the gap information is written. If left as the default, no log file will be created/updated. This file will not be affected by the nulled lines that are included in the output cube.

Type	filename
File Mode	output
Default	none
Filter	.txt .prt *.pvl

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Correlation Coefficient Tolerance: CORTOL

Description

This parameter determines how similar one line can be to the next and still be considerd part of a gap. A higher tolerance will result in gaps that are more similar to the surrounding area (possibly valid data). A tolerance closer to zero will result in gaps that are more different from the surrounding area (CORTOL=0.0 will give you gaps of null data).

Type	double
Default	0.0

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Buffer Size (Lines): ABOVE

Description

This parameter specifies how many lines above the gap are set to null in the output cube.

Type	integer
Default	7

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Buffer Size (Lines): BELOW

Description

This parameter specifies how many lines below the gap are set to null in the output cube.

Type	integer
Default	7

Close Window

Example 1

Finds Image Gaps

Description

This example shows how findgaps works on the cube I02025005RDR.cub.

Command Line

findgaps FROM=I02025005RDR.cub TO=cubeResults.cub LOG=logFileResults.txt ABOVE=10 BELOW=10

Searches I02025005RDR.cub for gaps based on the default Correlation Tolerance of CORTOL=0.0

Input Image

I02025005RDR.cub

A section of the input cube

Parameter Name: FROM

This image shows three null gaps.

Data File

Links open in a new window.

logFileResults.txt

In the case of no gaps, the LOG output file parameter will be empty.

When there are gaps in the cube image, then the gap information is reported in the LOG file if it is specified. In this example, that file is logFileResults.txt, as shown here. Each gap is displayed as a group consisting of the band number, the starting line number, the correlation coefficient that defined the line as gap, and the last line for a particular gap.

Output Image

cubeResults.cub

The same section as that shown for the input image.

Parameter Name: TO

This is the image cubeResults.cub that has null lines above and below each gap. You can see that 10 lines above and below the gap have been nulled out. The narrow strip of valid data in the middle of the image has been set to null due to the ABOVE and BELOW parameter settings. Reduce the value for ABOVE and BELOW to minimize the lines being set to NULL.

User Documentation

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Documentation Versions

ISIS 2

findgaps

Description

Categories

History

Parameter Groups

Files

Correlation Coefficient Tolerance

Buffer Size (Lines)

Files: FROM

Description

Files: TO

Description

Files: LOG

Description

Correlation Coefficient Tolerance: CORTOL

Description

Buffer Size (Lines): ABOVE

Description

Buffer Size (Lines): BELOW

Description

Example 1

Description

Command Line

Input Image

Data File

Output Image