RE: [Vxl-users] vil_warp

[Wheeler, F. (CRD) <wh...@cr...>]

Here is some code that warps an image according to a homography using vil_warp.

#include <vcl_iostream.h>
#include <vcl_fstream.h>
#include <vul/vul_arg.h>
#include <vnl/vnl_double_3x3.h>
#include <vil/vil_load.h>
#include <vil/vil_save.h>
#include <vil/vil_warp.h>

class h_mapping : public vil_warp_mapping {
public:
    h_mapping (const vnl_double_3x3 & H) : H_(H) { }
    virtual ~h_mapping () { }

    virtual void
    forward_map (double x1, double y1, double * x2, double * y2) const
    {
      assert (0);
    }

    virtual void
    inverse_map (double x2, double y2, double * x1, double * y1) const
    {
      double d = H_(2,0)*x2 + H_(2,1)*y2 + H_(2,2);
      *x1 = (H_(0,0)*x2 + H_(0,1)*y2 + H_(0,2)) / d;
      *y1 = (H_(1,0)*x2 + H_(1,1)*y2 + H_(1,2)) / d;
    }

private:
    vnl_double_3x3 H_;
};

int
main (int argc, char ** argv)
{
  vul_arg<char *> ifn("-i", "Input image filename", 0);
  vul_arg<char *> ofn("-o", "Output image filename", 0);
  vul_arg<char *> hfn("-h", "Homography filename", 0);
  vul_arg<int> ow ("-ow", "Output image width", -1);
  vul_arg<int> oh ("-oh", "Output image height", -1);
  vul_arg_parse (argc, argv);

  assert (ifn() && ofn() && hfn());

  vcl_ifstream hfs (hfn());
  vnl_double_3x3 H;
  hfs >> H;

  vil_image iimg = vil_load (ifn());
  h_mapping mapper (H);
  vil_image oimg = vil_warp (iimg, mapper, vil_warp_interpolation_bilinear,
                             ow(), oh());
  vil_save (oimg, ofn(), iimg.file_format());

  return 0;
}



-----Original Message-----
From: "Van Genechten, Bjorn"
[mailto:Bjo...@as...]
Sent: Thursday, March 14, 2002 5:53 AM
To: Vxl User List (E-mail)
Subject: [Vxl-users] vil_warp



Is there someone who has some example code available wich uses the
vil_warp methods ?


Thanks, 
     Bjorn