
vbilinco(1)                  Khoros                   vbilinco(1)

PROGRAM
     vbilinco - Compute bilinear geometric warp coefficients

SYNTAX
     vbilinco

     -i1            Source tie point image

     -i2            Target tie point image

     -o1            X vwarp coefficients image

     -o2            Y vwarp coefficients image

     [-o3]          Tiepoint Error Image

     [-V]           Gives the version for vbilinco

     [-U]           Gives the usage for vbilinco

     [-P]           Prompts for command line options

     [-A [file1]]   Creates the answer file called vbilinco.ans
                    or file1

     [-a [file1]]   Uses vbilinco.ans or file1 as the answer file

DESCRIPTION
     vbilinco is used to compute the coefficients for the two
     bilinear equations that are commonly used to perform image
     registration for simple spatial distortion functions. The
     input images are really files of coordinates.  Each input
     image should be of size N rows by 2 columns, of type FLOAT.
     There should be at least 4 tiepoints. If more than 4
     tiepoints are supplied then a least squares fit is done.
     The coordinates are stored as N pairs of numbers. For exam-
     ple (x0,y0) (x1,y1) (x2,y2) (x3,y3) is stored as an array of
     floats as follows:
          x0 y0
          x1 y1
          x2 y2
          x3 y3 which is exactly how vprdata(1) should print out
     your  coordinate file  if  it  is in the right order. The
     first input file contains the coordinates of the tie points
     in the  original (source)  image.  The  second input file
     contains the desired coordinates of the tie points in the
     corrected (target) image.

     The output files contain the coefficients for the  two  bil-
     inear transforms:
          x' = a + b*x + c*x*y + d*y
          y' = e + f*x + g*x*y + h*y where the point (x,y) is
     mapped to (x',y') by the transform.  The  coefficients  are
     stored  in  the output image as four floats (2 rows by 2
     columns), in the order
          a b
          d c     for the first image and

          e f
          h g     for the second image.

     The output image can be supplied directly to vwarp  to  per-
     form the geometric correction.

     The optional tiepoint error output image contains pairs of
     errors defined by (x'-x^),(y'-y^) where x^ is the approxima-
     tion that the bilinear function gives to the position of x'
     by position x.  This is a float image, with N rows and 2
     columns, with each row corresponding to the tiepoint in that
     same position.

REQUIRED ARGUMENTS
     -i1    type: infile
            desc: Source tie point image

     -i2    type: infile
            desc: Target tie point image

     -o1    type: outfile
            desc: X vwarp coefficients image

     -o2    type: outfile
            desc: Y vwarp coefficients image

OPTIONAL ARGUMENTS
     -o3    type: outfile
            desc: Tiepoint Error Image

EXAMPLES
     vbilinco -i1 src_tie.xv -i2 targ_tie.xv -o1 Xcoeffs.xv -o2
     Ycoeffs.xv

     computes the bilinear warp coefficients required to
     transform the input tiepoints specified into the specified
     target positions.

SEE ALSO
     intro(1), verror(3), vgparms(3), vutils(3), lvbilinco(3)
     vwarp(1), vpolyco(1)

RESTRICTIONS
     vbilinco will only operate on VFF_TYP_FLOAT.

COPYRIGHT
     Copyright 1991, University of New Mexico.  All rights
     reserved.

Khoros                    Release: 1.0                          1

