Rolled back Camera.cpp to get rid of failed merge of conflict.

  /**

   * @brief Improve the estimate of detector resolution when the target is near the limb 

   * This function provides an improved estimate of the detector resolution (in meters)

   * when the target is near the limb.  It does this by calculating the determinant of an affine

   * transformation. The area element of one pixel projected onto the surface at Nadir looks

   * like a square with sides of length = Detector Resolution.  The detector resolution is the

   * value returned by the original function.  An affine projective transformation of this

   * area element as one would see if it was on the limb instead of looking straight down, appears

   * like a skewed parallelogram.

   * @description This method returns the Oblique Detector Resolution

   * if the Look Vector intersects the target and if the emission angle is greater than or equal

   * to 0, and less than 90 degrees.   Otherwise, it returns -1.0.  This formula provides an

   * improved estimate to the detector resolution for images near the limb:

   *

   * The determinant of the transformation matrix taking the Nadir-area element into

   * some parallelogram near the limb of a planet measures the change in area for the

   * transformation when we are off-Nadir.  The sqare-root of the area of this parallelogram

   * gives us the resolution.

   *

   *The calculation is straightforward.  Any affine transformation with a strictly positive

   *determinant that is not a similarity transformation has a unique decomposition

   *(See Theorem 2.1 in Reference #1):

   * @f[ \text{Oblique\;\;Detector\;\; Resolution} = \frac{n}{cos(\theta)} @f]

   *

   *

   * The equation is derived two separate ways.  A geometric argument is presented in

   * Reference 2, while a matrix algebra based argument is presented in Theorem 2.1 of

   * Reference 1.

   *

   *

   * @f{eqnarray*}

   *

   *        A = \[\left[\begin{array}{cc} a & b \\

   *                                      c & d \end{array} \right]\] =

   *

   *         H_{\lambda}R_1(\psi)T_tR_2(\phi) = \lambda

   *        \[ \left[\begin{array}{cc} cos(\psi) & -sin(\psi) \\

   *                                   sin(\psi) & cos(\psi) \end{array} \right]\]

   *        \[ \left[\begin{array}{cc} t & 0 \\

   *                                   0 & 1 \end{array} \right]\]

   *        \[ \left[\begin{array}{cc} cos(\phi) & -sin(\phi) \\

   *                                   sin(\phi) & cos(\phi) \end{array} \right]\]

   *

   * @f}

   *

   * Where:

   *

   * @f$ t = \frac{1}{cos(\theta)}},\;\;\theta = \text{Emmission\;\; Angle}@f$

   * and @f$\lambda = \text{zoom\;\;factor} = 1@f$

   *

   *  The determinant of A is:

   *

   *  @f[ |A| = \lambda t = \frac{\lambda}{cos(\theta)} = \frac{1}{\cos(\theta)} @f]

   *

   * This is because the two rotation matrices in this decomposition have determinants equal to 1.

   *

   *  Let @f$ n = \text{Detector\;\;Resolution} @f$

   *

   *  Then:

   *

   *   @f[ Area = n^2 |A| =\frac{n^2}{cos(\theta)}@f]

   *

   * And:

   *

   *   @f[ \text{Local\;\;Detector\;\; Resolution} = \frac{n}{\sqrt{cos(\theta)}} @f]

   *

   *

   * This method returns the Local Detector Resolution if the Look Vector intersects the target

   * and if @f$ 0 \leq \theta < \frac{\pi}{2} @f$ and -1.0 otherwise.

   *

   *

   *

   *

   *   Reference 1:  J-M Morel and G. Yu, "Asift:  A new framework for fully affine

   *   <b>Reference 1:</b>  J-M Morel and G. Yu, "Asift:  A new framework for fully affine

   *                 invariant image comparison," SIAM Journal on Imaging Sciences

   *                 2(2), pp. 438-469, 2009

   *

   *

   *   <b>Reference 2:</b>  Handwritten notes by Orrin Thomas which can be found in the

   *                 Glossary under the entry for Oblique Detector Resolution.

   *

   * @return @b double

   */

  double Camera::ObliqueDetectorResolution(){

      if(HasSurfaceIntersection()){

          double thetaRad;          

          double sB[3];

          instrumentPosition(sB);

          double pB[3];

          Coordinate(pB);

          double a = sB[0] - pB[0];

          double b = sB[1] - pB[1];

          double c = sB[2] - pB[2];

          double rho = sqrt(a * a + b * b + c * c) * 1000.0;

          thetaRad = EmissionAngle()*DEG2RAD;

          if (thetaRad < HALFPI) {           

            double nadirResolution = rho/(p_focalLength/p_pixelPitch);

            return nadirResolution/sqrt(cos(thetaRad));

            return DetectorResolution()/cos(thetaRad);

          }

          return Isis::Null;