直观呈现几何图形
如需直观呈现几何图形,请将其添加到地图中。例如:
Code Editor (JavaScript)
// Create a geodesic polygon. var polygon = ee.Geometry.Polygon([ [[-5, 40], [65, 40], [65, 60], [-5, 60], [-5, 60]] ]); // Create a planar polygon. var planarPolygon = ee.Geometry(polygon, null, false); // Display the polygons by adding them to the map. Map.centerObject(polygon); Map.addLayer(polygon, {color: 'FF0000'}, 'geodesic polygon'); Map.addLayer(planarPolygon, {color: '000000'}, 'planar polygon');
如需详细了解可视化,请参阅地图项和 FeatureCollection 可视化。
几何图形信息和元数据
如需查看几何图形的相关信息,请输出该几何图形。如需以程序化方式访问这些信息,Earth Engine 提供了多种方法。例如,如需获取之前创建的多边形的相关信息,请使用以下命令:
Code Editor (JavaScript)
print('Polygon printout: ', polygon); // Print polygon area in square kilometers. print('Polygon area: ', polygon.area().divide(1000 * 1000)); // Print polygon perimeter length in kilometers. print('Polygon perimeter: ', polygon.perimeter().divide(1000)); // Print the geometry as a GeoJSON string. print('Polygon GeoJSON: ', polygon.toGeoJSONString()); // Print the GeoJSON 'type'. print('Geometry type: ', polygon.type()); // Print the coordinates as lists. print('Polygon coordinates: ', polygon.coordinates()); // Print whether the geometry is geodesic. print('Geodesic? ', polygon.geodesic());
请注意,除非指定投影,否则几何图形的周长(或长度)以米为单位,面积以平方米为单位。默认情况下,计算会基于 WGS84 球体执行,计算结果以米或平方米为单位。