原文链接及内容

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

运行界面

通过使用fromEPSGCode()方法，使COG能够在不同投影中的另一个图层上渲染的示例。

main.js代码如下：

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
import GeoTIFF from 'ol/source/GeoTIFF.js';
import Map from 'ol/Map.js';
import TileLayer from 'ol/layer/WebGLTile.js';
import XYZ from 'ol/source/XYZ.js';
import proj4 from 'proj4';
import {
  epsgLookupMapTiler,
  fromEPSGCode,
  register,
  setEPSGLookup,
} from 'ol/proj/proj4.js';

const key = 'Get your own API key at https://www.maptiler.com/cloud/';
const attributions =
  '<a href="https://www.maptiler.com/copyright/" target="_blank">&copy; MapTiler</a> ' +
  '<a href="https://www.openstreetmap.org/copyright" target="_blank">&copy; OpenStreetMap contributors</a>';

register(proj4);
setEPSGLookup(epsgLookupMapTiler(key));

const cogSource = new GeoTIFF({
  sources: [
    {
      url: 'https://mikenunn.net/data/MiniScale_(std_with_grid)_R23.tif',
      nodata: 0,
    },
  ],
});

cogSource.setAttributions(
  'Contains OS data © Crown Copyright and database right ' +
    new Date().getFullYear()
);

const map = new Map({
  target: 'map',
  layers: [
    new TileLayer({
      source: new XYZ({
        attributions: attributions,
        url:
          'https://api.maptiler.com/tiles/satellite/{z}/{x}/{y}.jpg?key=' + key,
        maxZoom: 20,
        crossOrigin: '',
      }),
      style: {exposure: 0.2},
    }),
    new TileLayer({
      source: cogSource,
      opacity: 0.7,
      style: {gamma: 0.7},
    }),
  ],
  view: cogSource
    .getView()
    .then((viewConfig) =>
      fromEPSGCode(viewConfig.projection.getCode()).then(() => viewConfig)
    ),
});

界面布局文件index.html代码如下：

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8">
    <title>COG with Projection Lookup</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>

    <script type="module" src="main.js"></script>
  </body>
</html>