ISIS 3 Application Documentation
Uses the input image footprints to find their intersections and writes these
intersections to a file for used in other programs such as autoseed.
Description
Several programs in Isis have an input parameter "OVERLAPLIST." This program
is designed to produce the OVERLAPLIST for other Isis programs to use.
An overlap list is a file describing how the images in a file list intersect
each other. The output contains encoded information that describes
how many cubes overlap in a particular latitude/longitude area. For example,
it might define "lub0454d.342.cub and lub0421c.342.cub overlap in longitudes
262.2 degrees to 270.3 degrees and latitudes -58.3 degrees to -60.3
degrees." The information in the file is much more precise than that, but
the general idea of the data is the same. Having image intersection
information is key for problems such as initial control point placement
The overlap list is generated using the footprints of the input images. A
requirement to running this program is running footprintinit on all
of your input files. The precision of the footprints directly affects the
precision of the overlap list/intersection information. If you
re-spiceinit or in any way change the SPICE data of an image then you should
re-run footprintinit and this program to update your image intersection
information. Programs that do not change SPICE data (for example,
calibration) do not require you to re-run this program.
The algorithm for finding these overlaps is:
-
Create a list of the image footprints
-
For each combination of items in the list (in the order of 1,2 1,3
1,4 2,3 2,4 3,4) where the first item is the left hand side and the
second item is the right hand side, do the following:
-
If the left and right hand side have overlapping serial numbers
associated with them then move on to the next combination of items
in the list.
-
If the lat/lon area associated with the left and right hand side are
identical, then copy the serial numbers from the right hand side
into the left hand side and delete the right hand side.
-
If the right hand side is empty or extremely tiny then delete it.
-
Intersect the left and right hand side.
-
If the intersection is empty or extremely tiny then move on to the
next combination of items in the list.
-
If the intersection is equal to the left hand side, then update
the right hand side to be itself minus the intersection. Update
the left hand side to have the right hand side's serial numbers.
Move on to the next combination of items in the list.
-
If the intersection is equal to the right hand side, then update
the left hand side to be itself minus the intersection. Update
the right hand side to have the left hand side's serial numbers.
Move on to the next combination of items in the list.
-
Subtract the intersection from the left hand side. If this fails,
try to subtract the right hand side from the left hand side to
automatically correct. Update the left hand side. Add the
intersection as a new item in the list with the serial numbers
of the left hand side.
Categories
History
Steven Lambright | 2008-11-03 |
Original version
|
Steven Lambright | 2008-11-24 |
Added the "DETAILED" and "ERRORS" parameters.
|
Steven Lambright | 2009-01-07 |
Added the number of errors to the results output
|
Steven Lambright | 2009-05-27 |
Uses different method call to ImageOverlapSet for optimization
|
Steven Lambright | 2009-05-28 |
The input list will be internally sorted by serial number so that
one list of input images will always produce the same results regardless
of the sort order.
|
Christopher Austin | 2010-03-26 |
Added an error when no new overlaps are calculated. (i.e. All overlaps
contain only a single Serial Number)
|
Christopher Austin | 2010-09-27 |
Moved the above error handling to ImageOverlapSet.
|
Steven Lambright | 2011-09-26 |
Improved documentation in preparation for the October release. Working
with me to document findimageoverlaps was Ra'ad Saleh and Bob Sucharski.
|
|
Parameter Groups
Files
Name
|
Description
|
FROMLIST |
List of input cubes to be intersected
|
OVERLAPLIST |
Output overlap list
|
ERRORS |
Error list file for errors generated when making the overlap list
|
Settings
Name
|
Description
|
DETAILED |
Output detailed error information
|
|
Files:
FROMLIST
Description
Use this parameter to specify the cubes for which we will find the
intersections of. If you are working with a control network then this
is the list of files associated with the control network.
Type
| filename |
File Mode
| input |
Filter
|
*.lis
|
Files:
OVERLAPLIST
Description
This file will contain the intersected image footprints in a non-human
readable format.
Type
| filename |
File Mode
| output |
Files:
ERRORS
Description
This file will contain the errors that occurred while calculating the
image overlaps. These errors are typically caused by complicated
math involving arbitrary polygons failing to produce an understandable
result and can often be alleviated by simplifying the input polygons.
Basically, the errors might be fixed by reducing the precision of
your image footprints; but increasing precision might fix them too.
Type
| filename |
File Mode
| output |
Internal Default
| No Error Output |
Settings:
DETAILED
Description
When this is set to true, and there is an errors file, the maximum
amount of information about each error is printed to the errors file.
When this is false, only filenames will be reported in the errors
file.
Type
| boolean |
Default
| false |