3D Tiles Photogrammetry Classification

<!--
  示例：地表要素的三分类着色
  说明：地面多边形、14 栋建筑与 40 个树冠椭球按三类配色渲染
  核心逻辑：polygon 铺地面 → box 表示建筑 → ellipsoid 表示树冠 → 三类各自取色
  依赖：CesiumJS 1.121 · jsDelivr CDN
-->
<!DOCTYPE html>
<html lang="zh-CN">
<head>
<meta name="robots" content="noindex,follow">
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1">
<title>地表要素的三分类着色</title>
<link rel="stylesheet" href="https://cdn.jsdelivr.net/npm/cesium@1.121.0/Build/Cesium/Widgets/widgets.css">
<style>
  html,body{height:100%;margin:0}
  body{background:#0e1116;color:#e6e8ec;overflow:hidden;
       font:13px/1.6 -apple-system,"Segoe UI","PingFang SC",sans-serif}
  #c{height:100%}
  .tip{position:absolute;left:12px;top:12px;z-index:5;
       background:rgba(23,28,35,.9);border:1px solid #2a313b;border-radius:6px;
       padding:8px 12px;font-size:12px;color:#a2a9b6;max-width:320px;line-height:1.6}
  .cesium-viewer-bottom .cesium-widget-credits,.cesium-viewer-animationContainer,
  .cesium-viewer-timelineContainer{display:none!important}

</style>
</head>
<body>
<div id="c"></div>
<div class="tip">灰色地面、蓝色建筑、绿色树冠，三种几何与三种颜色一一对应。</div>

<script src="https://cdn.jsdelivr.net/npm/cesium@1.121.0/Build/Cesium/Cesium.js"></script>
<script>
(function () {
  'use strict';

  var viewer = new Cesium.Viewer('c', {
    baseLayer: false,
    baseLayerPicker: false, geocoder: false, homeButton: false,
    sceneModePicker: false, navigationHelpButton: false,
    animation: false, timeline: false, fullscreenButton: false,
    infoBox: false, selectionIndicator: false
  });

  var scene = viewer.scene;
  scene.globe.baseColor = Cesium.Color.fromCssColorString('#1c2733');
  scene.backgroundColor = Cesium.Color.fromCssColorString('#0e1116');
  scene.skyBox.show = false;
  scene.sun.show = false;
  scene.moon.show = false;
  if (scene.skyAtmosphere) scene.skyAtmosphere.show = false;

  var west = 116.3846, south = 39.9018, east = 116.3970, north = 39.9122;

  /* 地面 */
  viewer.entities.add({
    polygon: {
      hierarchy: new Cesium.PolygonHierarchy(
        Cesium.Cartesian3.fromDegreesArray([west, south, east, south, east, north, west, north])),
      height: 0,
      material: Cesium.Color.fromCssColorString('#3a4557')
    }
  });

  var seed = 55;
  function rnd() { seed = (seed * 9301 + 49297) % 233280; return seed / 233280; }

  /* 建筑：冷色 */
  for (var i = 0; i < 14; i++) {
    var h = 20 + rnd() * 40;
    viewer.entities.add({
      position: Cesium.Cartesian3.fromDegrees(west + 0.0015 + rnd() * 0.0105,
                                              south + 0.0015 + rnd() * 0.0085, h / 2),
      box: {
        dimensions: new Cesium.Cartesian3(22, 20, h),
        material: Cesium.Color.fromCssColorString('#5b8def'),
        outline: true,
        outlineColor: Cesium.Color.fromCssColorString('#0b0f14')
      }
    });
  }

  /* 植被：绿色椭球 */
  for (var j = 0; j < 40; j++) {
    var r = 5 + rnd() * 5;
    viewer.entities.add({
      position: Cesium.Cartesian3.fromDegrees(west + 0.0012 + rnd() * 0.0108,
                                              south + 0.0012 + rnd() * 0.0090, r * 1.4),
      ellipsoid: {
        radii: new Cesium.Cartesian3(r, r, r * 1.3),
        material: Cesium.Color.fromCssColorString('#3ecf8e').withAlpha(0.85)
      }
    });
  }

  viewer.camera.flyTo({
    destination: Cesium.Cartesian3.fromDegrees(116.3832, 39.8982, 1350),
    orientation: { heading: Cesium.Math.toRadians(20), pitch: Cesium.Math.toRadians(-30), roll: 0 },
    duration: 0
  });
})();
</script>
</body>
</html>