INP=file1 is the input data set containing a
picture to be transformed in
standard VICAR format.
containing control parameters.
This data set must be created by the
routine XVPOUT. It contains keywords
and data for TIEPOINT, NAH and NAV
and can be used instead of specifying
these keywords in the TAE COMMAND LINE.
OUT=file2 is the output data set into which
the transformed picture is to be
written.
NAH=nh This keyword and associated number
specify the number of areas
horizontally. Its meaning is
explained in the Method section.
nh must be an integer.
If defaulted, NAH is read from a
tiepoint data set.
NAV=nv This keyword and associated number
specify the number of areas
vertically. Its meaning is
explained in the Method section.
nv must be an integer.
If defaulted, NAV is read from a
tiepoint data set.
TIEPOINT=(NEWLINE(1),NEWSAMP(1),
OLDLINE(1),OLDSAMP(1),
NEWLINE(2), ... )
This keyword and associated numbers
specify the mapping of control
points between output and input
pictures. This keyword must follow
the NAH and NAV keywords. The
numbers which follow the keyword
are in mutiples of four, one
multiple of four for each tiepoint.
The numbers may be either integer
or real type. The total number of
tiepoint numbers must be
4*(nh+1)*(nv+1)
Within each group of four numbers
describing a tiepoint, the first
number specifies the line coor-
dinate of that tiepoint in the
output (transformed) picture, the
second number specifies the sample
coordinate of that tiepoint in the
output picture, the third number
specifies the line coordinate of
the tiepoint in the input picture,
and the fourth number specifies the
sample coordinate of the tiepoint
in the input picture. The order in
which the tiepoints are specified
is left to right within a
horizontal row of tiepoints. The
horizontal rows of tiepoints are
specified in top-to-bottom
sequence. Tiepoint specification is
further clarified in the Operation
section.
SKIP=n This is used for skipping nominal
data. Two words of data are read
and then n words are skipped, etc.
The skipped data is carried along
unchanged to the output file.
IGNORE=(x,y) This causes all occurrences of the
point (x,y) to be left as is. The
default is to ignore the point
(0,0).
'INVERSE This keyword calls a reverse
transformation procedure to
calculate points in the original
image based on the output image.
Since the input to output relation-
ship is not exactly linear, the
equation is found in an iterative
process which approximates the
transformation equation used to
create the output file, applies it
to the original points, and tests
the approximated points against the
output control points. The dif-
ference is transformed backwards
and subtracted from the previous
point. Through this process the
error is reduced. When the error
is reduced to nearly zero the
solution is accepted. This
iterative process is relatively
efficient, converging the three
steps for most cases. (For further
explanation see the Operation
section.)
'INSECT This keyword specifies that points
are to be moved if inside the
parameter grid but points outside
are left as is.
'NOPRINT This keyword specifies that the usual messages output to the user are to be suppressed.