Google Earth Engine（GEE）——几何图形ee.Geometry

基础类型方法

类名	含义
ee.Geometry.LineString	线段：由一系列点组成的直线
ee.Geometry.LineRing	环：线段首尾相连接
ee.Geometry.MultiLineString	复合线段：多个线段组合在一起
ee.Geometry.Point	点
ee.Geometry.MultiPoint	复合点：多个点组合在一起
ee.Geometry.Polygon	多边形
ee.Geometry.Rectangle	矩形
ee.Geometry.MultiPolygon	复合矩形：多个矩形组合在一起

代码

var line = /* color: #d63000 */ee.Geometry.LineString(  
        [[-103.28593749999999, 38.46623315614578],  
         [-94.98027343749999, 40.534424706292405]]),  
    multiLine = /* color: #28db3e */ee.Geometry.MultiLineString(  
        [[[-101.70316271563797, 37.737101081855215],  
          [-96.46658167152503, 38.017322136064934]],  
         [[-105.74687499999999, 35.73286699047012],  
          [-100.34160156249999, 36.584391288158706]]]),  
    point = /* color: #0b4a8b */ee.Geometry.Point([-89.09160156249999, 39.7956206925268]),  
    multiPoint = /* color: #ffc82d */ee.Geometry.MultiPoint(  
        [[-92.65117187499999, 37.42662495543974],  
         [-93.79374999999999, 37.28690130733523]]),  
    polygon = /* color: #00ffff */ee.Geometry.Polygon(  
        [[[-96.86992187499999, 34.438354866968545],  
          [-95.55156249999999, 36.90132207718713],  
          [-97.74882812499999, 35.44697585969926]]]),  
    rectangle =  ee.Geometry.Polygon(  
        [[[-93.70585937499999, 36.44311350012563],  
          [-93.70585937499999, 33.63721310743895],  
          [-89.57499999999999, 33.63721310743895],  
          [-89.57499999999999, 36.44311350012563]]], null, false),  
    multiPolygon = /* color: #ff0000 */ee.Geometry.MultiPolygon(  
        [[[[-84.29587208507718, 39.96117602741789],  
           [-84.20893110596711, 38.095486162792234],  
           [-81.32717506033146, 40.59421005772966]]],  
         [[[-83.68632812499999, 34.7277971009936],  
           [-81.97246093749999, 37.8095219161184],  
           [-85.00468749999999, 37.63572230181635]]]]);  
             
Map.addLayer(line, {color: "d63000"}, "line");  
Map.addLayer(multiLine, {color: "28db3e"}, "multiLine");  
Map.addLayer(point, {color: "0b4a8b"}, "point");  
Map.addLayer(multiPoint, {color: "ffc82d"}, "multiPoint");  
Map.addLayer(polygon, {color: "00ffff"}, "polygon");  
Map.addLayer(rectangle, {color: "bf04c2"}, "rectangle");  
Map.addLayer(multiPolygon, {color: "ff0000"}, "multiPolygon");  
Map.centerObject(point, 4);

空间计算方法

（1）计算Geometry的面积使用area( )，返回值单位为平方米；

（2）提取Geometry的中心点使用centroid( )，返回值是对应Geometry的中心坐标；

（3）提取Geometry对应的外接矩形使用bounds( )；

（4）对Geometry做缓冲区域使用buffer( )，如果传入的距离是正整数则对Geometry做向外的扩大缓冲区域，如果传入的距离是负数则可以对Geometry做向内缩小的缓冲区域；

（5）判断两个Geometry是否相交使用intersects( )，返回两个Geometry是否相交的结果，如果两个Geometry相交则返回true，否则返回false；

（6）取得两个Geometry的相交部分内容使用intersection( )，，返回值是两个Geometry相交的新的Geometry；

（7）两个Geometry取得不同的部分使用difference( )，简单来说就是在第一个Geometry但不是不在第二个Geometry的部分。

代码

var polygon1 = /* color: #d63000 */ee.Geometry.Polygon(  
     [[[116.18363255709164, 39.73608336682765],  
          [116.62857884615414, 39.75297820506206],  
       [116.60660618990414, 40.08580181855619],  
          [116.15067357271664, 40.077395868796174]]]);  
var polygon2 = /* color: #ffc82d */ee.Geometry.Polygon(  
        [[[116.45728060961198, 40.23636657920226],  
          [116.42981478929948, 39.97166693527704],  
          [116.82806918383073, 39.95903650847623],  
          [116.88849398851823, 40.20700637790917]]]);  
Map.centerObject(polygon1, 9);  
Map.addLayer(polygon1, {color: "red"}, "polygon1");  
Map.addLayer(polygon2, {color: "blue"}, "polygon2");  
//polygon area  
print("polygon area is: ", polygon1.area());  
//polygon bounds  
print("polygon bounds is: ", polygon1.bounds());  
//polygon center point  
print("polygon centroid is: ", polygon1.centroid());  
//polygon coordinates  
print("polygon coordinates is: ", polygon1.coordinates());  
//check intersects  
print("polygon1 and polygon2 is intersects ?", polygon1.intersects(polygon2));  
var intersec = polygon1.intersection(polygon2);  
Map.addLayer(intersec, {}, "intersec");  
//outer 2000m  
var bufferPolygon1 = polygon1.buffer(2000);  
Map.addLayer(bufferPolygon1, {color:"ff00ff"}, "bufferPolygon1");  
//innner 2000m  
var bufferPolygon2 = polygon1.buffer(-2000);  
Map.addLayer(bufferPolygon2, {color:"00ffff"}, "bufferPolygon2");  
//difference  
var differ = bufferPolygon1.difference(bufferPolygon2);  
Map.addLayer(differ, {color:"green"}, "differ");