rspfDpt rspfTransCylEquAreaProjection::forward(const rspfGpt &latLon)const
{
double easting = 0.0;
double northing = 0.0;
rspfGpt gpt = latLon;
if (theDatum)
{
if (theDatum->code() != latLon.datum()->code())
{
gpt.changeDatum(theDatum); // Shift to our datum.
}
}
Convert_Geodetic_To_Trans_Cyl_Eq_Area(gpt.latr(),
gpt.lonr(),
&easting,
&northing);
return rspfDpt(easting, northing);
}
long Set_Trans_Cyl_Eq_Area_Parameters(double a,
double f,
double Origin_Latitude,
double Central_Meridian,
double False_Easting,
double False_Northing,
double Scale_Factor)
{ /* BEGIN Set_Trans_Cyl_Eq_Area_Parameters */
/*
* The function Set_Trans_Cyl_Eq_Area_Parameters receives the ellipsoid parameters and
* Transverse Cylindrical Equal Area projection parameters as inputs, and sets the
* corresponding state variables. If any errors occur, the error code(s) are returned
* by the function, otherwise TCEA_NO_ERROR is returned.
*
* a : Semi-major axis of ellipsoid, in meters (input)
* f : Flattening of ellipsoid (input)
* Origin_Latitude : 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
* origin latitude of the projection (input)
* Scale_Factor : Multiplier which reduces distances in the
* projection to the actual distance on the
* ellipsoid (input)
*/
double sin_lat_90 = sin(PI_OVER_2);
double x, j, three_es4;
double Sqrt_One_MINUS_es2;
double e1, e2, e3, e4;
double lat, sin2lat, sin4lat, sin6lat;
double temp, temp_northing;
double inv_f = 1 / f;
long Error_Code = TCEA_NO_ERROR;
if (a <= 0.0)
{ /* Semi-major axis must be greater than zero */
Error_Code |= TCEA_A_ERROR;
}
if ((inv_f < 250) || (inv_f > 350))
{ /* Inverse flattening must be between 250 and 350 */
Error_Code |= TCEA_INV_F_ERROR;
}
if ((Origin_Latitude < -PI_OVER_2) || (Origin_Latitude > PI_OVER_2))
{ /* origin latitude out of range */
Error_Code |= TCEA_ORIGIN_LAT_ERROR;
}
if ((Central_Meridian < -PI) || (Central_Meridian > TWO_PI))
{ /* origin longitude out of range */
Error_Code |= TCEA_CENT_MER_ERROR;
}
if ((Scale_Factor < MIN_SCALE_FACTOR) || (Scale_Factor > MAX_SCALE_FACTOR))
{
Error_Code |= TCEA_SCALE_FACTOR_ERROR;
}
if (!Error_Code)
{ /* no errors */
Tcea_a = a;
Tcea_f = f;
Tcea_Origin_Lat = Origin_Latitude;
if (Central_Meridian > PI)
Central_Meridian -= TWO_PI;
Tcea_Origin_Long = Central_Meridian;
Tcea_False_Northing = False_Northing;
Tcea_False_Easting = False_Easting;
Tcea_Scale_Factor = Scale_Factor;
es2 = 2 * Tcea_f - Tcea_f * Tcea_f;
es = sqrt(es2);
One_MINUS_es2 = 1.0 - es2;
Sqrt_One_MINUS_es2 = sqrt(One_MINUS_es2);
One_OVER_2es = 1.0 / (2.0 * es);
es4 = es2 * es2;
es6 = es4 * es2;
x = es * sin_lat_90;
qp = TCEA_Q(sin_lat_90,x);
a0 = es2 / 3.0 + 31.0 * es4 / 180.0 + 517.0 * es6 / 5040.0;
a1 = 23.0 * es4 / 360.0 + 251.0 * es6 / 3780.0;
a2 = 761.0 * es6 / 45360.0;
e1 = (1.0 - Sqrt_One_MINUS_es2) / (1.0 + Sqrt_One_MINUS_es2);
e2 = e1 * e1;
e3 = e2 * e1;
e4 = e3 * e1;
b0 = 3.0 * e1 / 2.0 - 27.0 * e3 / 32.0;
b1 = 21.0 * e2 / 16.0 - 55.0 * e4 / 32.0;
b2 = 151.0 * e3 / 96.0;
b3 = 1097.0 * e4 / 512.0;
j = 45.0 * es6 / 1024.0;
three_es4 = 3.0 * es4;
c0 = 1.0 - es2 / 4.0 - three_es4 / 64.0 - 5.0 * es6 / 256.0;
c1 = 3.0 * es2 / 8.0 + three_es4 / 32.0 + j;
c2 = 15.0 * es4 / 256.0 + j;
c3 = 35.0 * es6 / 3072.0;
lat = c0 * Tcea_Origin_Lat;
sin2lat = TCEA_COEFF_TIMES_SIN(c1, 2.0, Tcea_Origin_Lat);
sin4lat = TCEA_COEFF_TIMES_SIN(c2, 4.0, Tcea_Origin_Lat);
sin6lat = TCEA_COEFF_TIMES_SIN(c3, 6.0, Tcea_Origin_Lat);
M0 = TCEA_M(lat, sin2lat, sin4lat, sin6lat);
Convert_Geodetic_To_Trans_Cyl_Eq_Area(PI_OVER_2, PI, &temp, &temp_northing);
if (temp_northing > 0)
{
Tcea_Min_Northing = temp_northing - 20003931.458986;
Tcea_Max_Northing = temp_northing;
if(Tcea_False_Northing)
{
Tcea_Min_Northing -= Tcea_False_Northing;
Tcea_Max_Northing -= Tcea_False_Northing;
}
}
else if (temp_northing < 0)
{
Tcea_Max_Northing = temp_northing + 20003931.458986;
Tcea_Min_Northing = temp_northing;
if(Tcea_False_Northing)
{
Tcea_Min_Northing -= Tcea_False_Northing;
Tcea_Max_Northing -= Tcea_False_Northing;
}
}
} /* END OF if(!Error_Code) */
return (Error_Code);
} /* END OF Set_Trans_Cyl_Eq_Area_Parameters */
