coregpr2 Documentation

coregpr2 - Create control point file with 1/5 pixel registration
Programmer: AMCEWEN/TBECKER/KBECKER
coregpr2 finds control points between two images and writes them out
to an ascii file for input to RANDOM or WARP2.  The control points have
1/5 pixel registration accuracy.  For best results, coregpr2 should
collect values from user-specified 1) subareas surrounding sharp
features or 2) evenly-spaced subareas across the image. coregpr2 is
included in the procedure SUBPREG that runs through a subpixel
registration sequence (refer to the documentation of SUBPREG for
further details).

LTOL and STOL specify the maximum tolerance in line and sample expected
within each box.   LINE and SAMP specify the starting line and sample
in the images to start processing from (NOTE that only uder extremely
rare conditions would one want to use a subcube specifier for either
input image).  NLINES and NSAMPS specify the number of lines and
samples, respectively, in the box.  LINC and SINC specify the number
of lines and samples, respectively, to increment to the next box.
A special case of the NLINES=0 and/or NSAMPS=0 will result in the
increment set NLINES and/or NSAMPS.

Processing will start at LINE and SAMP and will continue to the
end of the current line through all lines.  Hence the total number
of boxes are a multiple of the number of boxes across the image
and down the image.

coregpr2 can be run in a single box mode per run by setting LINC
*AND* SINC to more lines and samples, respectively, than are in
the image.

The values of LOW and HIGH are used to exclude pixel values from the
computation of the registration.

The CFILE control point file will have points appended to it.
If the file does not exist it will be created.  If the file does
exist, points will be appended.  Management of this file is left soley
up to the user.

File name of the cube
that will be registered

NONE

Subcube specified for
FROM file

"::1"

Second input cube file
name.  Image will be
used to compute the
registration parameters

NONE

Subcube specified for
FROM2 file (Note: this
must select a single
band/image)

"::1"

Name of control file
to write points to

NONE

Maximum pixel misregistration
allowed in LINE dimension

10

Maximum pixel misregistration
allowed in SAMPLE dimension

10

Maximum box size

50

Minimum box size

--

Box size increment

1

Selects which box to use as
the best correlating box:
LAST    - Pick the last
          occuring box above
          GOODFIT
HIGH    - Pick the highest
          correlating box
          of all boxes above
          GOODFIT
AVERAGE - Compute the average
          of all boxes with a
          correlation
          coefficient greater
          than or equal to
          GOODFIT
NEARAVG - Same as AVERAGE but
          returns the actual box
          that is closest to
          this average
BESTTOL - Selects the box that
          has the highest sub-
          pixel correlation
          value (GOODFIT)
BESTFIT - Selects the box that
          has the lowest Chi-
          Square value, an
          indicator of how
          well the data fits
          the least square
          model.

"BESTTOL"

Log each point (Yes,No)

"NO"

Geom data (Yes,No)

"NO"

Order of of polynomial fit

1

Lowest value of valid DN

--

Highest value of valid DN

--

Minimum number points
that can be used to compute
registration

5

Fractional minimum of total
points used to compute
registration

0.0

Specifies the minimim
acceptable goodness of
fit/correlation between
the two images.  Correlation
range is 0 (worst) to 1
(best).

0.0

Starting sample to compute
pixel registration

1

Starting line to compute
pixel registration

1

Line increment for the box
LINC=0 will result in
LINC set to NLINES

0

Sample increment for the box
SINC=0 will result in
SINC set to NSAMPS

0

ADDITIONAL NOTES:

Parm	Description
FROM	The name of the input cube file. This file will be registered if the correlation is acceptable. (Default extention is .cub)
SFROM	The input subcube specifier. Allows the user to select a subarea of the input cube for processing. The specifier must select a single band/image and the dimensions must be equivalent to the FROM2 input file as well. The default "::1" selects all LINES, SAMPLES and the FIRST band from this file.
FROM2	The name of the secondary input cube file. This file contains the image that will be used to compute the pixel registration for the input (FROM) file. (Default extention is .cub)
SFROM2	The secondary input subcube specifier. Allows the user to select a subarea of the second (FROM2) input cube for processing. This specifier must select a single band/image and the dimensions of this input file must be equivalent to the input file (FROM). The default "::1" selects all LINES, SAMPLES and the FIRST band from this file.
CFILE	The name of the control file that will contain the points computed by coregpr2. Note that each run of coregpr2 will APPEND points to the end of this file if it already exists. If the file does not exist, it will be created by coregpr2.
LTOL	The maximum estimated pixel misregistration in the LINE dimension. LTOL must be greater than zero. If LTOL is less than or equal to zero, coregpr2 will assign LTOL to NLINES.
STOL	The maximum estimated pixel misregistration in the SAMPLE dimension. STOL must be greater than zero. If STOL is less than or equal to zero, coregpr2 will assign STOL to NSAMPS.
LOG	It is sometimes helpful to see how some points are registered especially if they are not sucessful. If LOG=YES, corepr2 will log each point and its boxes to the print file. If LOG=NO, no loggin will occur.
GEOM	This indicates whether the data needs to be geomed before trying to subpixel register. This will need to be done if the images are rotated from each other. For IMP images, it is best not to geom. Note that the truth point chip is always held fixed. The point being registered to the truth point is always the one that has the "fast" geometric transform applied to match truth point geometry.
EQORDER	EQORDER is the order of the polynomial equation used. Valid values are 1-8.
LOW	The lowest value of valid DNs. If LOW = 11, then pixels with DN values less than 11 will be excluded from processing.
HIGH	The highest value of valid DNs. If HIGH = 200, then values greater that 200 will be excluded from processing.
MIN	Specifies the minimum number of points that can be used to compute the pixel registration. This value should be such that a least square fit function can return resonable results. Note that FRAC may also be used to give an additional option on specifying this value. Note, however, that BOTH MIN and FRAC cannot be used. If this case does occur, the value of MIN will be used.
FRAC	This parameter can also be used to specify a fractional miniumum of the total points that can be used to compute the pixel registration. For example, if coregpr2 uses 2000 points maximum to compute the correlation and FRAC is 0.05, then the minimum number of points that can be used is MIN = (0.05 * 2000) = 100. Note, however, that BOTH MIN and FRAC cannot be used. If this case does occur, the value of MIN will be used.
GOODFIT	This parameter allows the user to specify a minimum acceptable goodness of fit. If the correlation bewteen the two images is less that GOODFIT, then the computed point will not be saved to the control file. This is NOT an error condition that will result in abnormal program termination. An error-like message is generated and reported to the user and the program exits normally. It is up to the user to determine the severity of such cases.
LINE	Specifies the starting line in BOTH input cubes where the registration is to be computed. Together with NLINES this determines the height of the box.
SAMP	This parameter specifies the starting sample in BOTH input cubes. Together with NSAMPS, this will determine the width of the box to use to register the two images.
BOXSIZE	This specifies the number of lines and samples in each box used to compute the registration.
MINBOX	Minimum box size. The smallest box size to be used to compute subpixel registrations for the image pair. If this parameter is not provided, then it will be set to BOXSIZE and only one image coregistration will be computed at the center of the image.
BOXINC	Specifies the increment of the "chip" box from MINBOX to BOXSIZE. BOXINC=1 will compute a chip registration at every size box from MINBOX to BOXSIZE. It can increment in any whole number greater than 0. The first "chip" registered will be done using MINBOX as the square size of the box. Each subsequent registration chip will be incremented by BOXINC and computed until the size of the box exceeds BOXSIZE. Then all the boxes are evaluated to determine the best registering chip. pecifies the increment of the "chip" box from MINBOX to BOXSIZE. BOXINC=1 will compute a chip registration at every size box from MINBOX to BOXSIZE. It can increment in any whole number greater than 0. The first "chip" registered will be done using MINBOX as the square size of the box. Each subsequent registration chip will be incremented by BOXINC and computed until the size of the box exceeds BOXSIZE. Then all the boxes are evaluated to determine the best registering chip.
BESTBOX	This parameter allows the user to choose which box is the best representation of a match. "LAST" will select the last occuring box in the first occuring span of registration correlations above GOODFIT. This cooresponds to the smallest box size in that span. "HIGH" will select the highest correlating box of all registrations in the first occuring span of value above GOODFIT. This is not always, or necessarily, the smallest box size. The "AVERAGE" option is computed using all boxes that have a correlation coefficient greater than or equal to GOODFIT. The average line and sample offsets are computed as well as the average of the correlation coefficient. The "NEARAVG" option is similar to the "AVERAGE" option except the actual box that is closest to the average is returned. This box is determined by the smallest absolute difference of the sums of both the line and sample offsets from the average. Note that the "AVERAGE" option will generate a completely separate box. With this option, the selected box will always show up in the SUCFILE as the last box indicated as the one selected. It will inherit many characteristics of the box nearest to this average as defined by the "NEARAVG" option. The "BESTTOL" option will select the box that has the highest tolerance value. The highest possible value that can be attained is 1.0 indicating perfect correlation between the two chips. It will only consider correlation coefficients greater than or equal to GOODFIT selecting the box with the highest GOODFIT value. It considers all boxes. The "BESTFIT" option will select the box that has the lowest Chi-Square value. Chi-Square is an indicator of how well the data fits the least square fit model. It is defined as the mean difference between the observed data and the least square model of the data at each point. A lower value indicates a better model. All boxes must also have a correlation coefficient greater than or equal to GOODFIT. Note that the "BESTTOL" and "BESTFIT" options will not always return the same box but will more times than not.
LINC	Line increment for the box. This value is the amount of line each registration box is moved down the image. This value may be used to define overlapping boxes or a single box in the line dimension. If LINC = 0, then it will be set to the value of NLINES.
SINC	Sample increment for the box. This value is the amount of samples each registration box is moved across the image. This value may be used to define overlapping boxes or a single box in the sample dimension. If SINC = 0, then it will be set to the value of NSAMPS.