www.pudn.com > GPU-KLT-1.0.zip > undistort_parametric.cg

/*
Copyright (c) 2008 University of North Carolina at Chapel Hill

This file is part of GPU-KLT.

GPU-KLT is free software: you can redistribute it and/or modify it under the
terms of the GNU Lesser General Public License as published by the Free
Software Foundation, either version 3 of the License, or (at your option) any
later version.

GPU-KLT is distributed in the hope that it will be useful, but WITHOUT ANY
WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
A PARTICULAR PURPOSE.  See the GNU Lesser General Public License for more
details.

You should have received a copy of the GNU Lesser General Public License along
with GPU-KLT. If not, see .
*/

void main(uniform sampler2D src_tex : TEXUNIT0,
          float2 st0 : TEXCOORD0,
          uniform float4 f, // fx and fy, 1/fx, 1/fy
          uniform float2 k, // k1 and k2
          uniform float2 p, // tangential parameters,
          uniform float2 center,
          uniform float4 wh, // with & height of the image, 1/w, 1/h
          out float3 color : COLOR)
{
   //float2 const x = st0 * wh.xy - float2(0.5);
   float2 const x = st0 - float2(0.5);

   // Points must be Bougouet-normalized
   // (subtract principal point, then divide by focal length)
   float2 const n = (x - center) * f.zw;

   float const twoxy = 2*n.x*n.y;
   //float const r2    = dot(n, n);
   float const r2    = n.x*n.x + n.y*n.y;
  
   // radial distortion:
   float const raddist  = 1 + k.x*r2 + k.y*r2*r2;

   // tangential distortion:
   float2 const tandist = p*twoxy + p.yx * (r2 + n*n);

   // apply distortion:
   float2 dist = raddist*n + tandist;
      
   // invert Bougouet-normalization
   dist = f.xy*dist + center;

#if 1
   // This is the path using bilinear interpolation of the texunits.
   // Go back to texture coords
   float2 const st = (dist + float2(0.5)) * wh.zw;

   // Texture lookup
   color = tex2D(src_tex, st).xyz;
#else
   // Here we do bilinear interpolation on our own.
   float2 ST = dist;

   float2 st00 = (floor(ST) + float2(0.5)) * wh.zw;
   float2 st11 = st00 + wh.zw;
   float2 st01 = float2(st00.x, st11.y);
   float2 st10 = float2(st11.x, st00.y);
   float2 W1 = frac(ST);
   float2 W2 = (1).xx - W1;
   float4 W = float4(0, 0, 0, 0);
   W.x = W2.x * W2.y;
   W.y = W2.x * W1.y;
   W.z = W1.x * W2.y;
   W.w = W1.x * W1.y;

   float3 res = float3(0, 0, 0);
   res += W.x * tex2D(src_tex, st00).xyz;
   res += W.y * tex2D(src_tex, st01).xyz;
   res += W.z * tex2D(src_tex, st10).xyz;
   res += W.w * tex2D(src_tex, st11).xyz;
   color = res;
#endif
}