cesium实现点聚合 举个例子

假设有一组地理坐标点数据，如下所示：

| 纬度 | 经度 |
| ---- | ---- |
| 31.231 | 121.473 |
| 31.231 | 121.475 |
| 31.233 | 121.477 |
| 31.235 | 121.475 |
| 31.237 | 121.473 |
| 31.239 | 121.471 |
| 31.241 | 121.469 |
| 31.243 | 121.471 |
| 31.245 | 121.473 |
| 31.247 | 121.475 |

我们可以使用Cesium实现点聚合，将附近的点合并成一个聚合点。具体实现步骤如下：

1. 创建Cesium Viewer对象：

var viewer = new Cesium.Viewer('cesiumContainer');

2. 将点数据转换成Cesium的Entity对象，并添加到Viewer中：

var entities = [];
var positions = [
    [31.231, 121.473],
    [31.231, 121.475],
    [31.233, 121.477],
    [31.235, 121.475],
    [31.237, 121.473],
    [31.239, 121.471],
    [31.241, 121.469],
    [31.243, 121.471],
    [31.245, 121.473],
    [31.247, 121.475]
];

for (var i = 0; i < positions.length; i++) {
    var position = Cesium.Cartesian3.fromDegrees(positions[i][1], positions[i][0]);
    var entity = new Cesium.Entity({
        position: position,
        point: {
            pixelSize: 10,
            color: Cesium.Color.RED
        }
    });
    entities.push(entity);
}

viewer.entities.add(entities);

3. 使用Cesium的Cluster实现点聚合：

var pixelRange = 50;
var minimumClusterSize = 3;
var cluster = new Cesium.Cluster({
    pixelRange: pixelRange,
    minimumClusterSize: minimumClusterSize,
    enabled: true
});

viewer.dataSources.add(cluster);

cluster.addEntities(entities);

以上代码中，我们使用了Cesium的Cluster对象，设置了聚合点的像素范围和最小聚合点数量。最后将Entity添加到Cluster中即可实现点聚合。

完整代码如下：

var viewer = new Cesium.Viewer('cesiumContainer');

var entities = [];
var positions = [
    [31.231, 121.473],
    [31.231, 121.475],
    [31.233, 121.477],
    [31.235, 121.475],
    [31.237, 121.473],
    [31.239, 121.471],
    [31.241, 121.469],
    [31.243, 121.471],
    [31.245, 121.473],
    [31.247, 121.475]
];

for (var i = 0; i < positions.length; i++) {
    var position = Cesium.Cartesian3.fromDegrees(positions[i][1], positions[i][0]);
    var entity = new Cesium.Entity({
        position: position,
        point: {
            pixelSize: 10,
            color: Cesium.Color.RED
        }
    });
    entities.push(entity);
}

var pixelRange = 50;
var minimumClusterSize = 3;
var cluster = new Cesium.Cluster({
    pixelRange: pixelRange,
    minimumClusterSize: minimumClusterSize,
    enabled: true
});

viewer.dataSources.add(cluster);

cluster.addEntities(entities);