ossimStereographicProjection.cpp

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//*******************************************************************
// Copyright (C) 2000 ImageLinks Inc.
//
// License:  See top LICENSE.txt file.
//
// Author:  Garrett Potts
//
//*******************************************************************
//  $Id: ossimStereographicProjection.cpp 9094 2006-06-13 19:12:40Z dburken $

#include <ossim/projection/ossimStereographicProjection.h>
#include <ossim/base/ossimKeywordNames.h>

RTTI_DEF1(ossimStereographicProjection, "ossimStereographicProjection", ossimMapProjection)

#ifndef PI_OVER_2
#  define PI_OVER_2  ( M_PI / 2.0)
#endif
#ifndef PI_OVER_4
#  define PI_OVER_4  ( M_PI / 4.0)
#endif
#ifndef TWO_PI
#  define TWO_PI     (2.0 * M_PI)
#endif
#define ONE    (1.0 * M_PI / 180.0)       /* 1 degree in radians*/

#define STEREO_NO_ERROR                0x0000
#define STEREO_LAT_ERROR               0x0001
#define STEREO_LON_ERROR               0x0002
#define STEREO_ORIGIN_LAT_ERROR        0x0004
#define STEREO_CENT_MER_ERROR          0x0008
#define STEREO_EASTING_ERROR                 0x0010
#define STEREO_NORTHING_ERROR              0x0020
#define STEREO_A_ERROR                 0x0040
#define STEREO_INV_F_ERROR             0x0080

ossimStereographicProjection::ossimStereographicProjection(const ossimEllipsoid& ellipsoid,
                                                       const ossimGpt& origin)
   :ossimMapProjection(ellipsoid, origin)
{
   setDefaults();
   update();
}

ossimStereographicProjection::ossimStereographicProjection(const ossimEllipsoid& ellipsoid,
                                                   const ossimGpt& origin,
                                                   double falseEasting,
                                                   double falseNorthing)
   :ossimMapProjection(ellipsoid, origin)
{
   Stereo_False_Easting  = falseEasting;
   Stereo_False_Northing = falseNorthing;
   Stereo_Delta_Easting  = 1460090226.0;
   Stereo_Delta_Northing = 1460090226.0;
   
   update();
}

void ossimStereographicProjection::update()
{   
   Set_Stereographic_Parameters(theEllipsoid.getA(),
                            theEllipsoid.getFlattening(),
                            theOrigin.latr(),
                            theOrigin.lonr(),
                            Stereo_False_Easting,
                            Stereo_False_Northing);

   theFalseEastingNorthing.x = Stereo_False_Easting;
   theFalseEastingNorthing.y = Stereo_False_Northing;

   ossimMapProjection::update();
}

void ossimStereographicProjection::setFalseEasting(double falseEasting)
{
   Stereo_False_Easting = falseEasting;
   
   update();
}

void ossimStereographicProjection::setFalseNorthing(double falseNorthing)
{
   Stereo_False_Northing = falseNorthing;
   
   update();
}

void ossimStereographicProjection::setDefaults()
{
   Stereo_False_Easting  = 0.0;
   Stereo_False_Northing = 0.0;
   Stereo_Delta_Easting  = 1460090226.0;
   Stereo_Delta_Northing = 1460090226.0;
}

void ossimStereographicProjection::setFalseEastingNorthing(double falseEasting,
                                                           double falseNorthing)
{
   Stereo_False_Easting  = falseEasting;
   Stereo_False_Northing = falseNorthing;
   
   update();
}

ossimGpt ossimStereographicProjection::inverse(const ossimDpt &eastingNorthing)const
{
   double lat = 0.0;
   double lon = 0.0;

   Convert_Stereographic_To_Geodetic(eastingNorthing.x,
                                 eastingNorthing.y,
                                 &lat,
                                 &lon);
   
   return ossimGpt(lat*DEG_PER_RAD, lon*DEG_PER_RAD, 0.0, theDatum);  
}

ossimDpt ossimStereographicProjection::forward(const ossimGpt &latLon)const
{
   double easting  = 0.0;
   double northing = 0.0;
   ossimGpt gpt = latLon;
   
   if (theDatum)
   {
      if (theDatum->code() != latLon.datum()->code())
      {
         gpt.changeDatum(theDatum); // Shift to our datum.
      }
   }

   Convert_Geodetic_To_Stereographic(gpt.latr(),
                                     gpt.lonr(),
                                     &easting,
                                     &northing);
   
   return ossimDpt(easting, northing);
}

bool ossimStereographicProjection::saveState(ossimKeywordlist& kwl, const char* prefix) const
{
   return ossimMapProjection::saveState(kwl, prefix);
}

bool ossimStereographicProjection::loadState(const ossimKeywordlist& kwl,
                                             const char* prefix)
{
   bool flag = ossimMapProjection::loadState(kwl, prefix);

   const char* type = kwl.find(prefix, ossimKeywordNames::TYPE_KW);
   
   setDefaults();

   if(ossimString(type) == STATIC_TYPE_NAME(ossimStereographicProjection))
   {
      Stereo_False_Easting  = theFalseEastingNorthing.x;
      Stereo_False_Northing = theFalseEastingNorthing.y;
   }
   
   update();

   return flag;
}
/************************************************************************/
/*                              FUNCTIONS
 *
 */

long ossimStereographicProjection::Set_Stereographic_Parameters (double a,
                                                                 double f,
                                                                 double Origin_Latitude,
                                                                 double Central_Meridian,
                                                                 double False_Easting,
                                                                 double False_Northing)

{  /* BEGIN Set_Stereographic_Parameters   */
/*  
 *  The function Set_Stereographic_Parameters receives the ellipsoid
 *  parameters and Stereograpic projection parameters as inputs, and
 *  sets the corresponding state variables.  If any errors occur, error
 *  code(s) are returned by the function, otherwise STEREO_NO_ERROR is returned.
 *
 *  a                : Semi-major axis of ellipsoid, in meters         (input)
 *  f                : Flattening of ellipsoid                                 (input)
 *  Origin_Latitude  : Latitude, in radians, at the center of          (input)
 *                       the projection
 *  Central_Meridian : Longitude, in radians, at the center of         (input)
 *                       the projection
 *  False_Easting    : Easting (X) at center of projection, in meters  (input)
 *  False_Northing   : Northing (Y) at center of projection, in meters (input)
 */

  double es2, es4, es6;
  double temp = 0;
//  double inv_f = 1 / f;
  long Error_Code = STEREO_NO_ERROR;

//   if (a <= 0.0)
//   { /* Semi-major axis must be greater than zero */
//     Error_Code |= STEREO_A_ERROR;
//   }
//   if ((inv_f < 250) || (inv_f > 350))
//   { /* Inverse flattening must be between 250 and 350 */
//     Error_Code |= STEREO_INV_F_ERROR;
//   }
//   if ((Origin_Latitude < -PI_OVER_2) || (Origin_Latitude > PI_OVER_2))
//   { /* origin latitude out of range */
//     Error_Code |= STEREO_ORIGIN_LAT_ERROR;
//   }
//   if ((Central_Meridian < -M_PI) || (Central_Meridian > TWO_PI))
//   { /* origin longitude out of range */
//     Error_Code |= STEREO_CENT_MER_ERROR;
//   }
  if (!Error_Code)
  { /* no errors */
    Stereo_a = a;
    Stereo_f = f;
    es2 = 2 * Stereo_f - Stereo_f * Stereo_f;
    es4 = es2 * es2;
    es6 = es4 * es2;
    Stereo_Ra = Stereo_a * (1.0 - es2 / 6.0 - 17.0 * es4 / 360.0 - 67.0 * es6 /3024.0);
    Two_Stereo_Ra = 2.0 * Stereo_Ra;
    Stereo_Origin_Lat = Origin_Latitude;
    Sin_Stereo_Origin_Lat = sin(Stereo_Origin_Lat);
    Cos_Stereo_Origin_Lat = cos(Stereo_Origin_Lat);
//     if (Central_Meridian > M_PI)
//       Central_Meridian -= TWO_PI;
    Stereo_Origin_Long = Central_Meridian;
    Stereo_False_Easting = False_Easting;
    Stereo_False_Northing = False_Northing;
    if(fabs(fabs(Stereo_Origin_Lat) - PI_OVER_2) < 1.0e-10)
      Stereo_At_Pole = 1;
    else
      Stereo_At_Pole = 0;

    if ((Stereo_At_Pole) || (fabs(Stereo_Origin_Lat) < 1.0e-10))
    {
      Stereo_Delta_Easting = 1460090226.0;
    }
    else
    {
      if (Stereo_Origin_Long <= 0)
        Convert_Geodetic_To_Stereographic(-Stereo_Origin_Lat, M_PI + Stereo_Origin_Long - ONE, &Stereo_Delta_Easting, &temp);
      else
        Convert_Geodetic_To_Stereographic(-Stereo_Origin_Lat, Stereo_Origin_Long - M_PI - ONE, &Stereo_Delta_Easting, &temp);
    }

  } /* END OF if(!Error_Code) */
  return (Error_Code);
} /* END OF Set_Stereographic_Parameters */

void ossimStereographicProjection::Get_Stereographic_Parameters(double *a,
                                                                double *f,
                                                                double *Origin_Latitude,
                                                                double *Central_Meridian,
                                                                double *False_Easting,
                                                                double *False_Northing)const

{ /* BEGIN Get_Stereographic_Parameters */
/*
 * The function Get_Stereographic_Parameters returns the current ellipsoid
 * parameters and Stereographic projection parameters.
 *
 *    a                 : Semi-major axis of ellipsoid, in meters   (output)
 *    f                 : Flattening of ellipsoid                               (output)
 *    Origin_Latitude   : Latitude, in radians, at the center of    (output)
 *                          the projection
 *    Central_Meridian  : Longitude, in radians, at the center of   (output)
 *                          the projection
 *    False_Easting     : A coordinate value, in meters, assigned to the
 *                          central meridian of the projection.     (output)
 *    False_Northing    : A coordinate value, in meters, assigned to the
 *                          origin latitude of the projection       (output) 
 */

  *a = Stereo_a;
  *f = Stereo_f;
  *Origin_Latitude = Stereo_Origin_Lat;
  *Central_Meridian = Stereo_Origin_Long;
  *False_Easting = Stereo_False_Easting;
  *False_Northing = Stereo_False_Northing;
  
  return;
} /* END OF Get_Stereographic_Parameters */

long ossimStereographicProjection::Convert_Geodetic_To_Stereographic (double Latitude,
                                                                      double Longitude,
                                                                      double *Easting,
                                                                      double *Northing)const

{  /* BEGIN Convert_Geodetic_To_Stereographic */

/*
 * The function Convert_Geodetic_To_Stereographic converts geodetic
 * coordinates (latitude and longitude) to Stereographic coordinates
 * (easting and northing), according to the current ellipsoid
 * and Stereographic projection parameters. If any errors occur, error
 * code(s) are returned by the function, otherwise STEREO_NO_ERROR is returned.
 *
 *    Latitude   :  Latitude, in radians                      (input)
 *    Longitude  :  Longitude, in radians                     (input)
 *    Easting    :  Easting (X), in meters                    (output)
 *    Northing   :  Northing (Y), in meters                   (output)
 */

  double g, k;
  double num = 0;
  double Ra_k = 0;
  double slat = sin(Latitude);
  double clat = cos(Latitude);
  double dlam;                        /* Longitude - Central Meridan */
  double cos_dlam;
  long   Error_Code = STEREO_NO_ERROR;

//   if ((Latitude < -PI_OVER_2) || (Latitude > PI_OVER_2))
//   {  /* Latitude out of range */
//     Error_Code |= STEREO_LAT_ERROR;
//   }
//   if ((Longitude < -M_PI) || (Longitude > TWO_PI))
//   {  /* Longitude out of range */
//     Error_Code|= STEREO_LON_ERROR;
//   }
  if (!Error_Code)
  {  /* no errors */


    dlam = Longitude - Stereo_Origin_Long;
//     if (dlam > M_PI)
//     {
//       dlam -= TWO_PI;
//     }
//     if (dlam < -M_PI)
//     {
//       dlam += TWO_PI;
//     }

    cos_dlam = cos(dlam);
    g = 1.0 + Sin_Stereo_Origin_Lat * slat + Cos_Stereo_Origin_Lat * clat * cos_dlam;
    if (fabs(g) <= 1.0e-10)
    {  /* Point is out of view.  Will return longitude out of range message
          since no point out of view is implemented.  */
      Error_Code |= STEREO_LON_ERROR;
    }
    else
    {
      if (Stereo_At_Pole)
      {
        if (fabs(fabs(Latitude) - PI_OVER_2) < 1.0e-10)
        {
          *Easting = Stereo_False_Easting;
          *Northing = Stereo_False_Northing;
        }
        else
        {
          if (Stereo_Origin_Lat > 0)
          {
            num = Two_Stereo_Ra * tan(PI_OVER_4 - Latitude / 2.0);
            *Easting = Stereo_False_Easting + num * sin(dlam);
            *Northing = Stereo_False_Northing + (-num * cos_dlam);
          }
          else
          {
            num = Two_Stereo_Ra * tan(PI_OVER_4 + Latitude / 2.0);
            *Easting = Stereo_False_Easting + num * sin(dlam);
            *Northing = Stereo_False_Northing + num * cos_dlam;
          }
        }
      }
      else
      {
        if (fabs(Stereo_Origin_Lat) <= 1.0e-10)
        {
          k = 2.0 / (1.0 + clat * cos_dlam);
          Ra_k = Stereo_Ra * k;
          *Northing = Stereo_False_Northing + Ra_k * slat;
        }
        else
        {
          k = 2.0 / g;
          Ra_k = Stereo_Ra * k;
          *Northing = Stereo_False_Northing + Ra_k * (Cos_Stereo_Origin_Lat * slat - Sin_Stereo_Origin_Lat * clat * cos_dlam);
        }
        *Easting = Stereo_False_Easting + Ra_k * clat * sin(dlam);
      }
    }
  }
  return (Error_Code);
} /* END OF Convert_Geodetic_To_Stereographic */
  
long ossimStereographicProjection::Convert_Stereographic_To_Geodetic(double Easting,
                                                                     double Northing,
                                                                     double *Latitude,
                                                                     double *Longitude)const
{ /* BEGIN Convert_Stereographic_To_Geodetic */
/*
 * The function Convert_Stereographic_To_Geodetic converts Stereographic projection
 * (easting and northing) coordinates to geodetic (latitude and longitude)
 * coordinates, according to the current ellipsoid and Stereographic projection
 * coordinates.  If any errors occur, the error code(s) are returned by the
 * function, otherwise STEREO_NO_ERROR is returned.
 *
 *    Easting           : Easting (X), in meters              (input)
 *    Northing          : Northing (Y), in meters             (input)
 *    Latitude          : Latitude (phi), in radians          (output)
 *    Longitude         : Longitude (lambda), in radians      (output)
 */

  double dx, dy;
  double rho, c;
  double sin_c, cos_c;
  double dy_sin_c;
  long Error_Code = STEREO_NO_ERROR;

//   if ((Easting < (Stereo_False_Easting - Stereo_Delta_Easting))
//       ||(Easting > (Stereo_False_Easting + Stereo_Delta_Easting)))
//   { /* Easting out of range  */
//     Error_Code |= STEREO_EASTING_ERROR;
//   }
//   if ((Northing < (Stereo_False_Northing - Stereo_Delta_Northing))
//       || (Northing > (Stereo_False_Northing + Stereo_Delta_Northing)))
//   { /* Northing out of range */
//     Error_Code |= STEREO_NORTHING_ERROR;
//   }
  if (!Error_Code)
  { /* no errors */

    dy = Northing - Stereo_False_Northing;
    dx = Easting - Stereo_False_Easting;
    rho = sqrt(dx * dx + dy * dy);
    if (fabs(rho) <= 1.0e-10)
    {
      *Latitude = Stereo_Origin_Lat;
      *Longitude = Stereo_Origin_Long;
    }
    else
    {
      c = 2.0 * atan(rho / (Two_Stereo_Ra));
      sin_c = sin(c);
      cos_c = cos(c);
      dy_sin_c = dy * sin_c;
      if (Stereo_At_Pole)
      {
        if (Stereo_Origin_Lat > 0)
          *Longitude = Stereo_Origin_Long + atan2(dx, -dy);
        else
          *Longitude = Stereo_Origin_Long + atan2(dx, dy);
      }
      else
        *Longitude = Stereo_Origin_Long + atan2(dx * sin_c, (rho * Cos_Stereo_Origin_Lat * cos_c - dy_sin_c * Sin_Stereo_Origin_Lat));
      *Latitude = asin(cos_c * Sin_Stereo_Origin_Lat + ((dy_sin_c * Cos_Stereo_Origin_Lat) / rho));
    }

//     if (fabs(*Latitude) < 2.2e-8)  /* force lat to 0 to avoid -0 degrees */
//       *Latitude = 0.0;
//     if (*Latitude > PI_OVER_2)  /* force distorted values to 90, -90 degrees */
//       *Latitude = PI_OVER_2;
//     else if (*Latitude < -PI_OVER_2)
//       *Latitude = -PI_OVER_2;

//     if (*Longitude > M_PI)
//     {
//       if (*Longitude - M_PI < 3.5e-6) 
//         *Longitude = M_PI;
//       else
//         *Longitude -= TWO_PI;
//     }
//     if (*Longitude < -M_PI)
//     {
//       if (fabs(*Longitude + M_PI) < 3.5e-6)
//         *Longitude = -M_PI;
//       else
//         *Longitude += TWO_PI;
//     }
//
//     if (fabs(*Longitude) < 2.0e-7)  /* force lon to 0 to avoid -0 degrees */
//       *Longitude = 0.0;
//     if (*Longitude > M_PI)  /* force distorted values to 180, -180 degrees */
//       *Longitude = M_PI;
//     else if (*Longitude < -M_PI)
//       *Longitude = -M_PI;
  }
  return (Error_Code);
} /* END OF Convert_Stereographic_To_Geodetic */