Google Earth Engine（GEE）——點、線、面和省級行政區的加載和展示，以及矢量的過濾篩選

這裡簡單說一下first()函數：傳回影像或者矢量集合中的第一個

first()

Returns the first entry from a given collection.

Arguments:

this:collection (FeatureCollection):

The collection from which to select the first entry.

Returns: Element

代碼：

var point = ee.Geometry.Point([116.387928, 40.00649]);//
var line = ee.Geometry.LineString(  
    [[116.3782558270866, 40.02023566292988],
          [116.3782558270866, 39.9984096033757],
          [116.41069982733075, 39.9984096033757],
          [116.41069982733075, 40.02023566292988]]);  
var polygon = ee.Geometry.Polygon(
      [[[116.3