Geozarr Groups

<!--
  示例：GeoZarr 多组数据 — OpenLayers geozarr-groups
  核心逻辑：同一份影像数据挂两个 Raster 图层，一组出彩色合成，一组出云掩膜
  依赖：OpenLayers 10.3.1 · 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>GeoZarr 多组数据</title>
<link rel="stylesheet" href="https://cdn.jsdelivr.net/npm/ol@10.3.1/ol.css">
<style>
  html,body{height:100%;margin:0}
  body{display:flex;flex-direction:column;overflow:hidden;
       font:13px/1.6 -apple-system,"Segoe UI","PingFang SC",sans-serif}
  .bar{flex:0 0 auto;padding:8px 12px;background:#f6f7f9;border-bottom:1px solid #e3e6ea;
       display:flex;gap:12px;align-items:center;font-size:12px;color:#58606e;flex-wrap:wrap}
  .bar label{display:flex;gap:5px;align-items:center;cursor:pointer}
  #map{flex:1 1 auto;min-height:0;background:#eef0f3}
</style>
</head>
<body>
<div class="bar">
  <label><input type="checkbox" id="surface" checked> 地表反射率组</label>
  <label><input type="checkbox" id="cloud" checked> 云掩膜组</label>
  <span id="info">—</span>
</div>
<div id="map"></div>
<script src="https://cdn.jsdelivr.net/npm/ol@10.3.1/dist/ol.js"></script>
<script>
(function () {
  'use strict';

  if (typeof ol === 'undefined') {
    document.getElementById('map').innerHTML =
      '<div style="padding:20px;color:#b42318">OpenLayers 加载失败，请检查能否访问 cdn.jsdelivr.net</div>';
    return;
  }

  /* 生成三通道反射率，云带按亮度混合成高亮区域 */
  function makeScene() {
    var size = 512;
    var c = document.createElement('canvas');
    c.width = size;
    c.height = size;
    var ctx = c.getContext('2d');
    var img = ctx.createImageData(size, size);

    for (var y = 0; y < size; y++) {
      for (var x = 0; x < size; x++) {
        var veg = 0.5 + 0.3 * Math.sin(x / 39) * Math.cos(y / 47);
        var i = (y * size + x) * 4;

        var r = 70 + 45 * (1 - veg);
        var g = 80 + 110 * veg;
        var b = 90 + 40 * (1 - veg);

        /* 云带：两条斜向高亮条纹 */
        var cloud = Math.max(0, Math.sin((x + y * 0.6) / 55) - 0.35) * 1.6;
        cloud = Math.min(1, cloud);

        img.data[i] = Math.round(r * (1 - cloud) + 246 * cloud);
        img.data[i + 1] = Math.round(g * (1 - cloud) + 248 * cloud);
        img.data[i + 2] = Math.round(b * (1 - cloud) + 250 * cloud);
        img.data[i + 3] = 255;
      }
    }
    ctx.putImageData(img, 0, 0);
    return c.toDataURL();
  }

  var extent = ol.proj.transformExtent(
    [116.15, 39.78, 116.60, 40.06], 'EPSG:4326', 'EPSG:3857'
  );

  var scene = new ol.source.ImageStatic({
    url: makeScene(),
    projection: 'EPSG:3857',
    imageExtent: extent,
    crossOrigin: 'anonymous'
  });

  /* 组一：三通道拉伸成真彩 */
  var surfaceLayer = new ol.layer.Image({
    source: new ol.source.Raster({
      sources: [scene],
      operation: function (pixels) {
        var src = pixels[0];
        var out = new Uint8ClampedArray(src.length);
        for (var i = 0; i < src.length; i += 4) {
          out[i] = Math.min(255, src[i] * 1.5);
          out[i + 1] = Math.min(255, src[i + 1] * 1.35);
          out[i + 2] = Math.min(255, src[i + 2] * 1.6);
          out[i + 3] = 255;
        }
        return out;
      }
    }),
    opacity: 0.85
  });

  /* 组二：云概率高于阈值才保留颜色，其余透明 */
  var cloudLayer = new ol.layer.Image({
    source: new ol.source.Raster({
      sources: [scene],
      operation: function (pixels) {
        var src = pixels[0];
        var out = new Uint8ClampedArray(src.length);
        for (var i = 0; i < src.length; i += 4) {
          /* 用亮度估计云概率：云带被混合成接近白色 */
          var lum = (src[i] + src[i + 1] + src[i + 2]) / 3;
          var p = Math.max(0, Math.min(1, (lum - 165) / 80));
          if (p > 0.35) {
            var v = Math.round(235 - p * 35);
            out[i] = v;
            out[i + 1] = v;
            out[i + 2] = v;
            out[i + 3] = Math.min(255, Math.round(p * 320));
          } else {
            out[i + 3] = 0;
          }
        }
        return out;
      }
    }),
    opacity: 0.9
  });

  var map = new ol.Map({
    target: 'map',
    layers: [
      new ol.layer.Tile({ source: new ol.source.XYZ({url: 'https://server.arcgisonline.com/ArcGIS/rest/services/World_Street_Map/MapServer/tile/{z}/{y}/{x}', attributions: 'Tiles © Esri'}), opacity: 0.5 }),
      surfaceLayer,
      cloudLayer
    ],
    view: new ol.View({
      center: ol.proj.fromLonLat([116.38, 39.92]),
      zoom: 11,
      minZoom: 2
    }),
    controls: ol.control.defaults.defaults({ attribution: false })
  });

  function update() {
    var s = document.getElementById('surface').checked;
    var c = document.getElementById('cloud').checked;
    document.getElementById('info').textContent =
      '可见组：' + [s ? '反射率' : '', c ? '云掩膜' : ''].filter(Boolean).join(' + ') ||
      '无';
  }

  document.getElementById('surface').addEventListener('change', function () {
    surfaceLayer.setVisible(this.checked);
    update();
  });
  document.getElementById('cloud').addEventListener('change', function () {
    cloudLayer.setVisible(this.checked);
    update();
  });

  update();
})();
</script>
</body>
</html>