Sentinel 2

<!--
  示例：Sentinel-2 波段合成
  说明：把红、绿、近红三个波段合成为一张假彩色影像，压在城市区域的球面上
  核心逻辑：三个波段的灰度值 → canvas 通道合成 → SingleTileImageryProvider
  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>Sentinel-2 波段合成</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">红波段进红通道、近红外进绿通道，植被呈现亮绿色，这是常用的假彩色组合。</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;

  /* 生成三个波段的灰度场：模拟红、绿、近红 */
  function band(kind) {
    var n = 96, data = [];
    for (var y = 0; y < n; y++) {
      for (var x = 0; x < n; x++) {
        var v = 0.45 + 0.28 * Math.sin(x * 0.18 + kind) + 0.2 * Math.cos(y * 0.14 - kind);
        data.push(Math.max(0, Math.min(1, v)));
      }
    }
    return data;
  }

  var red = band(0), green = band(1), nir = band(2);

  function compose() {
    var n = 96, c = document.createElement('canvas');
    c.width = c.height = n;
    var ctx = c.getContext('2d');
    var img = ctx.createImageData(n, n);
    for (var i = 0; i < n * n; i++) {
      /* 假彩色：近红外 → 红通道，红波段 → 绿通道，绿波段 → 蓝通道 */
      img.data[i * 4] = nir[i] * 255;
      img.data[i * 4 + 1] = red[i] * 255;
      img.data[i * 4 + 2] = green[i] * 255;
      img.data[i * 4 + 3] = 255;
    }
    ctx.putImageData(img, 0, 0);
    return c.toDataURL('image/png');
  }

  var layer = viewer.imageryLayers.addImageryProvider(
    new Cesium.SingleTileImageryProvider({
      url: compose(),
      rectangle: Cesium.Rectangle.fromDegrees(115.9, 39.5, 116.9, 40.2)
    })
  );
  layer.contrast = 1.3;
  layer.saturation = 1.4;
  viewer.camera.flyTo({
    destination: Cesium.Rectangle.fromDegrees(115.9, 39.5, 116.9, 40.2),
    duration: 0
  });
})();
</script>
</body>
</html>