原文链接及内容

原文链接：https://openlayers.org/en/latest/examples/cog-overviews.html

运行界面

在某些情况下，GeoTIFF可能具有外部概视图。下面的示例将为数据源的overviews属性设置一个URL，以便加载包含外部概视图的文件。

main.js代码如下：

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import GeoTIFF from 'ol/source/GeoTIFF.js';
import Map from 'ol/Map.js';
import TileLayer from 'ol/layer/WebGLTile.js';

const source = new GeoTIFF({
  sources: [
    {
      url: 'https://openlayers.org/data/raster/no-overviews.tif',
      overviews: ['https://openlayers.org/data/raster/no-overviews.tif.ovr'],
    },
  ],
});

const map = new Map({
  target: 'map',
  layers: [
    new TileLayer({
      source: source,
    }),
  ],
  view: source.getView(),
});

界面布局文件index.html代码如下：

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<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8">
    <title>GeoTIFF with Overviews</title>
    <link rel="stylesheet" href="node_modules/ol/ol.css">
    <style>
      .map {
        width: 100%;
        height: 400px;
      }
    </style>
  </head>
  <body>
    <div id="map" class="map"></div>
    <!-- Pointer events polyfill for old browsers, see https://caniuse.com/#feat=pointer -->
    <script src="https://cdn.jsdelivr.net/npm/elm-pep@1.0.6/dist/elm-pep.js"></script>
    <script type="module" src="main.js"></script>
  </body>
</html>