LroNarrowAngleDistortionMap.cpp

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#include <cmath>

#include "IString.h"
#include "LroNarrowAngleDistortionMap.h"

namespace Isis {
  LroNarrowAngleDistortionMap::LroNarrowAngleDistortionMap(Camera *parent) : CameraDistortionMap(parent, 1) {
  }

  void LroNarrowAngleDistortionMap::SetDistortion(const int naifIkCode) {
    QString odkkey = "INS" + toString(naifIkCode) + "_OD_K";
    p_odk.clear();
    p_odk.push_back(p_camera->getDouble(odkkey, 0));
  }

  bool LroNarrowAngleDistortionMap::SetFocalPlane(const double dx, const double dy) {
    p_focalPlaneX = dx;
    p_focalPlaneY = dy;

    double dk1 = p_odk[0];

    double den = 1 + dk1 * dy * dy;                 // r = dy*dy = distance from the focal plane center
    if(den == 0.0)
      return false;

    p_undistortedFocalPlaneX = dx;
    p_undistortedFocalPlaneY = dy / den;

    return true;
  }

  bool LroNarrowAngleDistortionMap::SetUndistortedFocalPlane(const double ux, const double uy) {
    // image coordinates prior to introducing distortion
    p_undistortedFocalPlaneX = ux;
    p_undistortedFocalPlaneY = uy;

    double yt = uy;

    double rr, dr;
    double ydistorted;
    double yprevious = 1000000.0;
    double tolerance = 1.0e-10;

    bool bConverged = false;

    double dk1 = p_odk[0];

    // Owing to the odd distotion model employed in this senser if |y| is > 116.881145553046
    //  then there is no root to find.  Further, the greatest y that any measure on the sensor
    //  will acutally distort to is less than 20.  Thus, if any distorted measure is greater
    //  that that skip the iterations.  The points isn't in the cube, and exactly how far outside
    //  the cube is irrelevant.  Just let the camera model know its not in the cube....
    if (fabs(uy) > 40) {  //if the point is way off the image.....
      p_focalPlaneX = p_undistortedFocalPlaneX;
      p_focalPlaneY = 100.0;  //100.0 is >> 20.0, and clearly outside the cube
      return true;
    }

    // iterating to introduce distortion (in sample only)...
    // we stop when the difference between distorted coordinate
    // in successive iterations is at or below the given tolerance
    for(int i = 0; i < 50; i++) {
      rr = yt * yt;

      //  dr is the radial distortion contribution
      dr = 1.0 + dk1 * rr;

      // distortion at the current sample location
      yt = uy * dr;

      // distorted sample
      ydistorted = yt;

      if (yt < -1e121)  //debug
        break;  //debug

      // check for convergence
      if(fabs(yt - yprevious) <= tolerance) {
        bConverged = true;
        break;
      }

      yprevious = yt;
    }
    
    if(bConverged) {
      p_focalPlaneX = p_undistortedFocalPlaneX;
      p_focalPlaneY = ydistorted;
    }

    return bConverged;
  }
}