ossimDpt ossimEquDistCylProjection::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_Equidistant_Cyl(gpt.latr(),
gpt.lonr(),
&easting,
&northing);
return ossimDpt(easting, northing);
}
long Set_Equidistant_Cyl_Parameters(double a,
double f,
double Std_Parallel,
double Central_Meridian,
double False_Easting,
double False_Northing)
{ /* Begin Set_Equidistant_Cyl_Parameters */
/*
* The function Set_Equidistant_Cyl_Parameters receives the ellipsoid parameters and
* projection parameters as inputs, and sets the corresponding state
* variables. It also calculates the spherical radius of the sphere having
* the same area as the ellipsoid. If any errors occur, the error code(s)
* are returned by the function, otherwise EQCY_NO_ERROR is returned.
*
* a : Semi-major axis of ellipsoid, in meters (input)
* f : Flattening of ellipsoid (input)
* Std_Parallel : Latitude in radians at which the (input)
* point scale factor is 1.0
* Central_Meridian : Longitude in radians at the center of (input)
* the projection
* False_Easting : A coordinate value in meters assigned to the
* central meridian of the projection. (input)
* False_Northing : A coordinate value in meters assigned to the
* standard parallel of the projection (input)
*/
double temp;
double inv_f = 1 / f;
long Error_Code = EQCY_NO_ERROR;
if (a <= 0.0)
{ /* Semi-major axis must be greater than zero */
Error_Code |= EQCY_A_ERROR;
}
if ((inv_f < 250) || (inv_f > 350))
{ /* Inverse flattening must be between 250 and 350 */
Error_Code |= EQCY_INV_F_ERROR;
}
if ((Std_Parallel < -PI_OVER_2) || (Std_Parallel > PI_OVER_2))
{ /* standard parallel out of range */
Error_Code |= EQCY_STDP_ERROR;
}
if ((Central_Meridian < -PI) || (Central_Meridian > TWO_PI))
{ /* origin longitude out of range */
Error_Code |= EQCY_CENT_MER_ERROR;
}
if (!Error_Code)
{ /* no errors */
Eqcy_a = a;
Eqcy_f = f;
es2 = 2 * Eqcy_f - Eqcy_f * Eqcy_f;
es4 = es2 * es2;
es6 = es4 * es2;
/* spherical radius */
Ra = Eqcy_a * (1.0 - es2 / 6.0 - 17.0 * es4 / 360.0 - 67.0 * es6 /3024.0);
Eqcy_Std_Parallel = Std_Parallel;
Cos_Eqcy_Std_Parallel = cos(Eqcy_Std_Parallel);
Ra_Cos_Eqcy_Std_Parallel = Ra * Cos_Eqcy_Std_Parallel;
if (Central_Meridian > PI)
Central_Meridian -= TWO_PI;
Eqcy_Origin_Long = Central_Meridian;
Eqcy_False_Easting = False_Easting;
Eqcy_False_Northing = False_Northing;
if (Eqcy_Origin_Long > 0)
{
Convert_Geodetic_To_Equidistant_Cyl(PI_OVER_2, Eqcy_Origin_Long - PI - ONE, &Eqcy_Max_Easting, &temp);
Convert_Geodetic_To_Equidistant_Cyl(PI_OVER_2, Eqcy_Origin_Long - PI, &Eqcy_Min_Easting, &temp);
}
else if (Eqcy_Origin_Long < 0)
{
Convert_Geodetic_To_Equidistant_Cyl(PI_OVER_2, Eqcy_Origin_Long + PI, &Eqcy_Max_Easting, &temp);
Convert_Geodetic_To_Equidistant_Cyl(PI_OVER_2, Eqcy_Origin_Long + PI + ONE, &Eqcy_Min_Easting, &temp);
}
else
{
Convert_Geodetic_To_Equidistant_Cyl(PI_OVER_2, PI, &Eqcy_Max_Easting, &temp);
Eqcy_Min_Easting = -Eqcy_Max_Easting;
}
Eqcy_Delta_Northing = Ra * PI_OVER_2;
} /* End if(!Error_Code) */
return (Error_Code);
} /* End Set_Equidistant_Cyl_Parameters */
