GEE使用多边形创建要素集

使用多边形创建要素集

主要功能

使用自定义的多边形来创建要素集

代码

// Create and render a feature collection from polygons.

// Construct a FeatureCollection from a list of features.
var fc = ee.FeatureCollection([
  // Create each feature with a geometry and properties.
  ee.Feature(
      ee.Geometry.Polygon({
        coords: [[-109.05, 41], [-109.05, 37], [-102.05, 37], [-102.05, 41]],
        geodesic: false, // The state boundaries are not geodesic.
        maxError: 1000 // Make the error margin large; we don't need accuracy.
      }), {name: 'Colorado', fill: 1}), // Pass properties as a dictionary.
  ee.Feature(
      ee.Geometry.Polygon({
        coords: [
          [-114.05, 37.0], [-109.05, 37.0], [-109.05, 41.0],
          [-111.05, 41.0], [-111.05, 42.0], [-114.05, 42.0]
        ],
        geodesic: false,
        maxError: 1000
      }), {name: 'Utah', fill: 2})
]);

// Fill, then outline the polygons into a blank image.
var image = ee.Image().toByte()
    .paint(fc, 'fill') // Get color from property named 'fill'
    .paint(fc, 3, 5); // Outline using color 3, width 5.

Map.addLayer(image, {
    palette: ['000000', 'FF0000', '00FF00', '0000FF'],
    max: 3,
    opacity: 0.5
});

Map.setCenter(-107, 41, 6);

步骤分析

1. 使用拐点坐标和属性列表来创建若干个地理要素
2. 使要素集包含创建的地理要素对象
3. 将要素集输出为影像数据对象
4. 添加要素对象显示图层
5. 设置地图中心，缩放等级

主要方法

1. ee.FeatureCollection()
   FeatureCollections can be constructed from the following arguments:

• A string: assumed to be the name of a collection.
• A single geometry.
• A single feature.
• A list of features.
• A computed object: reinterpreted as a collection.
  Arguments:
  args (ComputedObject|Feature|FeatureCollection|Geometry|List