GIS风场及其相关技术研究三

VectorField.read = function(data) {
	var field = [];
	var w = data[0].header.nx;
	var h = data[0].header.ny;
	var n = 2 * w * h;
	var i = 0;
	
	var total = 0;
	var weight = 0;
	for (var x = 0; x < w; x++) {
		field[x] = [];
		for (var y = 0; y < h; y++) {
			var vx = data[0].data[w*y+x];
			var vy = data[1].data[w*y+x];
			var v = new Vector(vx, vy);
			var ux = x / (w - 1);
			var uy = y / (h - 1);
			var lon =  data[0].header.lo1 * (1 - ux) + data[0].header.lo2 * ux; // 获取矢量场的经度坐标，类似于X0+ux(X1-X0)
			var lat =  data[0].header.la1 * (1 - uy) + data[0].header.la2 * uy;
			var m = Math.PI * lat / 180;
			var length = v.length();
			if (length) {
			    total += length * m;
			    weight += m;
	    	}
			v.x /= Math.cos(m);
			v.setLength(length);
			field[x].push(v);
		}
	}
	var result = new VectorField(field, data[0].header.lo1, data[0].header.la1, data[0].header.lo2, data[0].header.la2);
  // window.console.log('total = ' + total);
	// window.console.log('weight = ' + weight);
  if (total && weight) {

	  result.averageLength = total / weight;
	}
	return result;
};