INP=a Input image: rectangular for forward
transformation, polar for inverse.
OUT=b Output image: polar for forward
transformation, rectangular for inverse.
SIZE=(SL,SS,NLO,NSO)
is the standard VICAR size field. SL
and SS refer to starting offsets with
respect to the input image.NLO and NSO
refer to the desired output picture
size.
'INVERSE Input is in polar coordinate format,
and is to be transformed to
rectangular coordinate format (default
is rectangular to polar transformation).
BACK=I I is the DN value of all points in the
output image which are not contained
in the input.
'NOINTERP This keyword specifies that there is
to be no bilinear interpolation for
output pixels which correspond to
inter-pixel area in the input. The
nearest pixel value is used (default
is to perform bilinear interpolation).
FORWARD:
XCEN,X X(REAL) is the rectangular sample
coordinate for the origin of the polar
coordinate system. Default is NSI/2.,
where NSI is the input picture line
length in pixels.
INVERSE:
XCEN,X X (REAL) is the rectangular sample
coordinate to which the points defined
by R=0. are mapped. Default is to
obtain X from the history labels.
FORWARD:
YCEN,Y Y(REAL) is the rectangular line
coordinate for the origin of the polar
coordinate system. Default is NLI/2.,
where NLI is the number of lines in
the input picture.
INVERSE:
YCEN,Y Y (REAL) is the rectangular line
coordinate to which the points defined
by R=0. are mapped. Default is to
obtain Y from the history labels.
FORWARD:
RANGE,A1,A2 A1 and A2 (REAL) are the angular
limits of the sector in the input
picture which is to be transformed to
polar coordinates when taken with
respect to the polar origin defined by
XCEN and YCEN. Default is to set A1
and A2, to include entire input
picture. A1 and A2 are expressed in
degrees. See parameter RESO. (A2-A1
360.,A1 -90.)
INVERSE:
RANGE,A1,A2 A1 and A2 (REAL) are the angular
limits, in degrees, of the polar
coordinate picture. A1 corresponds to
the input angle at line 1 and A2 to
the at line NL(INPUT). Default is to
obtain A1 and A2 from the history
labels. (A2-A1 360.,A1 -90.)
FORWARD:
RMIN,R1 R1(REAL) is the minimum radius, in
pixels from the polar origin, of the
sector to be included in the transfor-
mation. Default is R1=0. if the polar
origin is within the input image, or
the radius corresponding to the
closest point in the input image if
the polar origin is not within the
input image.
INVERSE:
RMIN,R1 R1 (REAL) is the radius in the polar
input corresponding to the first to
the first pixel of each input line.
Default is to obtain R1 from the
history labels.
FORWARD:
RMAX,R2 R2 (REAL) is the maximum radius, in
pixels from the polar origin, of the
sector to be included in the transfor-
mation. Default is to set R2 to be
the radius corresponding to the point
in the input sector which is furthest
from the polar origin. See parameter
RSCALE.
INVERSE:
RMAX,R2 R2 (REAL) is the radius in the polar
input corresponding to the last pixel
of each input line. Default is to
obtain R2 from the history labels.
FORWARD:
RESO=B B (REAL) is the angular resolution, in
degrees of the polar coordinate
picture. One line spacing in the polar
coordinate image corresponds to B
degrees. Default is B=arctan(1./R2).
Note that the default for B retains
all pixel separation, and
interpolation is between pixels for
all radii less than R2. The number of
output lines necessary to contain the
entire sector of input is NL=(A2-A1)/B+1,
so that B may be considered a
scaling factor in the line direction
for fitting the output image to the
output picture size constraints. See
parameter AUTO.
INVERSE:
RESO=B B (REAL) is the angular change in each
line of the polar input specified in
degrees and is defined as:
B=(A2-A1)/(NL -1).
IN
Default is to calculate B based on the
history labels.
FORWARD:
RSCALE=S S (REAL) is the radial scaling factor
(as RESO is the angular scaling
factor) for compression or expansion
of the output picture in the radial
direction. Default is S=1.. For S>1.,
the output picture is compressed, and
for 0.<S<1., the output picture is
expanded. See parameter AUTO.
INVERSE:
RSCALE=S S (REAL) is the radial scaling factor
and is defined as:
S=(R2-R1)/(NS -1) (NS =PIXELS)
IN IN
Default is to calculate S based on the
history labels.
FORWARD:
'NOLABEL This parameter specifies that there is
to be no history label update. The
default is to perform a history label
update on the output picture, quanti-
tatively describing the forward
transformation for future use by the
INVERSE mode. The use of label
updating is recommended because of the
cumbersome calculations required of
the user for the "INVERSE MODE"
parameters.
INVERSE:
'NOLABEL This parameter specifies that there
are NO history labels on the input
data set specifying the parameter used
by the forward mode. If the history
labels created by the forward mode
still exist on the input data set, and
the user desires to transform the
polar coordinate input to rectangular
coordinate output, with EXACTLY the
reverse transformation of the forward
mode, the only parameter necessary is
INVERSE. Default is that POLARECT
history labels are assumed to exist on
the input data set, and all input
parameters not specified in the
parameter list are obtained from the
history labels.
'AUTO This parameter fits the input sector
to the output picture size specified
in the VICAR size field by adjusting
the angular resolution parameter B and
the radial scaling factor S as
follows:
S=(R2-R1)/(NSout-1) (NSout=PIXELS)
B=(A2-A1)/(NLout-1).
By the use of this parameter, the user
is assured that the output picture is
filled with the desired sector, with
no loss of data due to truncation of
data at output picture boundaries.