经纬度坐标下的球面多边形面积计算JavaScript源码文库.doc

经纬度坐标下的球面多边形面积计算公式这两天看到有人询问WGS84下的多边形面积计算。一般说来，经纬度坐标多边形面积指的是球面多边形面积。我曾经在作ArcIMS项目时写了一个Javascript函数，特贴出来，大家需要时可以参考。为方便大家直接调用，我做了简单修改，如果有问题，请批评指正。还需要注意的是，该函数不适用于自交*多边形。Copy to clipboardCODE:/ calculate Areafunction calcArea(PointX,PointY,MapUnits) var Count = PointX.length if (Count3) var mtotalArea = 0; if(PointX0!=PointXCount-1)|(PointY0!=PointYCount-1) return; if (MapUnits=DEGREES)/经纬度坐标下的球面多边形 var LowX=0.0; var LowY=0.0; var MiddleX=0.0; var MiddleY=0.0; var HighX=0.0; var HighY=0.0; var AM = 0.0; var BM = 0.0; var CM = 0.0; var AL = 0.0; var BL = 0.0; var CL = 0.0; var AH = 0.0; var BH = 0.0; var CH = 0.0; var CoefficientL = 0.0; var CoefficientH = 0.0; var ALtangent = 0.0; var BLtangent = 0.0; var CLtangent = 0.0; var AHtangent = 0.0; var BHtangent = 0.0; var CHtangent = 0.0; var ANormalLine = 0.0; var BNormalLine = 0.0; var CNormalLine = 0.0; var OrientationValue = 0.0; var AngleCos = 0.0; var Sum1 = 0.0; var Sum2 = 0.0; var Count2 = 0; var Count1 = 0; var Sum = 0.0; var Radius = 6378000; for(i=0;i0) Sum1 += AngleCos; Count1 +; else Sum2 += AngleCos; Count2 +; /Sum +=2*Math.PI-AngleCos; if(Sum1Sum2) Sum = Sum1+(2*Math.PI*Count2-Sum2); else Sum = (2*Math.PI*Count1-Sum1)+Sum2; /平方米 mtotalArea = (Sum-(Count-2)*Math.PI)*Radius*Radius; else /非经纬度坐标下的平面多边形 var i,j; var j; var p1x,p1y; var p2x,p2y; for(i=Count-1, j=0; jCount; i=j, j+) if(i=Count-1) p1x = mX; p1y = mY; else p1x = PointXi; p1y = PointYi; if(j=Count-1) p2x = mX; p2y = mY; else p2x = PointXj; p2y = PointYj; mtotalArea +=p1x*p2y-p2x*p1y; mtotalArea /= 2.0; return mtotalArea; return;不太好注释，具体