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109 lines
3.7 KiB
JavaScript
109 lines
3.7 KiB
JavaScript
/*******************************************************************************
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NAME CASSINI
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PURPOSE: Transforms input longitude and latitude to Easting and
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Northing for the Cassini projection. The
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longitude and latitude must be in radians. The Easting
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and Northing values will be returned in meters.
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Ported from PROJ.4.
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ALGORITHM REFERENCES
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1. Snyder, John P., "Map Projections--A Working Manual", U.S. Geological
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Survey Professional Paper 1395 (Supersedes USGS Bulletin 1532), United
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State Government Printing Office, Washington D.C., 1987.
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2. Snyder, John P. and Voxland, Philip M., "An Album of Map Projections",
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U.S. Geological Survey Professional Paper 1453 , United State Government
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*******************************************************************************/
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//Proj4js.defs["EPSG:28191"] = "+proj=cass +lat_0=31.73409694444445 +lon_0=35.21208055555556 +x_0=170251.555 +y_0=126867.909 +a=6378300.789 +b=6356566.435 +towgs84=-275.722,94.7824,340.894,-8.001,-4.42,-11.821,1 +units=m +no_defs";
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// Initialize the Cassini projection
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// -----------------------------------------------------------------
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Proj4js.Proj.cass = {
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init : function() {
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if (!this.sphere) {
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this.en = Proj4js.common.pj_enfn(this.es)
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this.m0 = Proj4js.common.pj_mlfn(this.lat0, Math.sin(this.lat0), Math.cos(this.lat0), this.en);
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}
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},
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C1: .16666666666666666666,
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C2: .00833333333333333333,
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C3: .04166666666666666666,
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C4: .33333333333333333333,
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C5: .06666666666666666666,
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/* Cassini forward equations--mapping lat,long to x,y
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-----------------------------------------------------------------------*/
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forward: function(p) {
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/* Forward equations
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-----------------*/
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var x,y;
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var lam=p.x;
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var phi=p.y;
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lam = Proj4js.common.adjust_lon(lam - this.long0);
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if (this.sphere) {
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x = Math.asin(Math.cos(phi) * Math.sin(lam));
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y = Math.atan2(Math.tan(phi) , Math.cos(lam)) - this.phi0;
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} else {
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//ellipsoid
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this.n = Math.sin(phi);
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this.c = Math.cos(phi);
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y = Proj4js.common.pj_mlfn(phi, this.n, this.c, this.en);
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this.n = 1./Math.sqrt(1. - this.es * this.n * this.n);
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this.tn = Math.tan(phi);
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this.t = this.tn * this.tn;
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this.a1 = lam * this.c;
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this.c *= this.es * this.c / (1 - this.es);
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this.a2 = this.a1 * this.a1;
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x = this.n * this.a1 * (1. - this.a2 * this.t * (this.C1 - (8. - this.t + 8. * this.c) * this.a2 * this.C2));
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y -= this.m0 - this.n * this.tn * this.a2 * (.5 + (5. - this.t + 6. * this.c) * this.a2 * this.C3);
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}
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p.x = this.a*x + this.x0;
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p.y = this.a*y + this.y0;
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return p;
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},//cassFwd()
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/* Inverse equations
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-----------------*/
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inverse: function(p) {
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p.x -= this.x0;
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p.y -= this.y0;
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var x = p.x/this.a;
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var y = p.y/this.a;
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var phi, lam;
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if (this.sphere) {
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this.dd = y + this.lat0;
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phi = Math.asin(Math.sin(this.dd) * Math.cos(x));
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lam = Math.atan2(Math.tan(x), Math.cos(this.dd));
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} else {
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/* ellipsoid */
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var ph1 = Proj4js.common.pj_inv_mlfn(this.m0 + y, this.es, this.en);
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this.tn = Math.tan(ph1);
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this.t = this.tn * this.tn;
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this.n = Math.sin(ph1);
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this.r = 1. / (1. - this.es * this.n * this.n);
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this.n = Math.sqrt(this.r);
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this.r *= (1. - this.es) * this.n;
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this.dd = x / this.n;
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this.d2 = this.dd * this.dd;
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phi = ph1 - (this.n * this.tn / this.r) * this.d2 * (.5 - (1. + 3. * this.t) * this.d2 * this.C3);
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lam = this.dd * (1. + this.t * this.d2 * (-this.C4 + (1. + 3. * this.t) * this.d2 * this.C5)) / Math.cos(ph1);
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}
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p.x = Proj4js.common.adjust_lon(this.long0+lam);
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p.y = phi;
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return p;
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}//cassInv()
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}
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