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WMTS 瓦片转换

发布于 2022-11-30 23:36:07 字数 4636 浏览 0 评论 0 收藏 0

本示例演示改变 WMTS 图层维度参数（dimension）的时候平滑转换瓦片

本示例演示连续改变维度参数（dimension）时平滑的载入图层。示例中演示的图层是全球海平面计算数据（洪水计算来自SCALGO，底层数据来自CGIAR-CSISRTM）。当海平面上升到 x 米的时候，被淹没的地方会被染成蓝色。用户可以使用滑块调整海平面的高度。

main.js

import 'ol/ol.css';
import Map from 'ol/Map';
import OSM from 'ol/source/OSM';
import TileLayer from 'ol/layer/Tile';
import View from 'ol/View';
import WMTS from 'ol/source/WMTS';
import WMTSTileGrid from 'ol/tilegrid/WMTS';
import {get as getProjection} from 'ol/proj';
import {getTopLeft, getWidth} from 'ol/extent';

// create the WMTS tile grid in the google projection
const projection = getProjection('EPSG:3857');
const tileSizePixels = 256;
const tileSizeMtrs = getWidth(projection.getExtent()) / tileSizePixels;
const matrixIds = [];
const resolutions = [];
for (let i = 0; i <= 14; i++) {
  matrixIds[i] = i;
  resolutions[i] = tileSizeMtrs / Math.pow(2, i);
}
const tileGrid = new WMTSTileGrid({
  origin: getTopLeft(projection.getExtent()),
  resolutions: resolutions,
  matrixIds: matrixIds,
});

const scalgoToken = 'CC5BF28A7D96B320C7DFBFD1236B5BEB';

const wmtsSource = new WMTS({
  url: 'https://ts2.scalgo.com/olpatch/wmts?token=' + scalgoToken,
  layer: 'SRTM_4_1:SRTM_4_1_flooded_sealevels',
  format: 'image/png',
  matrixSet: 'EPSG:3857',
  attributions: [
    '<a href="https://scalgo.com" target="_blank">SCALGO</a>',
    '<a href="https://cgiarcsi.community/data/' +
      'srtm-90m-digital-elevation-database-v4-1"' +
      ' target="_blank">CGIAR-CSI SRTM</a>',
  ],
  tileGrid: tileGrid,
  style: 'default',
  dimensions: {
    'threshold': 100,
  },
});

const map = new Map({
  target: 'map',
  view: new View({
    projection: projection,
    center: [-9871995, 3566245],
    zoom: 6,
  }),
  layers: [
    new TileLayer({
      source: new OSM(),
    }),
    new TileLayer({
      opacity: 0.5,
      source: wmtsSource,
    }),
  ],
});

const slider = document.getElementById('slider');
const updateSourceDimension = function () {
  wmtsSource.updateDimensions({'threshold': slider.value});
  document.getElementById('theinfo').innerHTML = slider.value + ' meters';
};
slider.addEventListener('input', updateSourceDimension);
slider.addEventListener('change', updateSourceDimension);
updateSourceDimension();

index.html

<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8">
    <title>WMTS Tile Transitions</title>
    <!-- Pointer events polyfill for old browsers, see https://caniuse.com/#feat=pointer -->
    <script src="https://unpkg.com/elm-pep"></script>
    <!-- The line below is only needed for old environments like Internet Explorer and Android 4.x -->
    <script src="https://cdn.polyfill.io/v3/polyfill.min.js?features=fetch,requestAnimationFrame,Element.prototype.classList,URL,TextDecoder,Number.isInteger"></script>
    <style>
      .map {
        width: 100%;
        height:400px;
      }
    </style>
  </head>
  <body>
    <div id="map" class="map"></div>
    <label>
      Sea-level
      <input id="slider" type="range" value="10" max="100" min="-1">
    </label>
    <span id="theinfo"></span>
    <script src="main.js"></script>
  </body>
</html>

package.json

{
  "name": "wmts-dimensions",
  "dependencies": {
    "ol": "7.1.0"
  },
  "devDependencies": {
    "parcel": "^2.0.0-beta.1"
  },
  "scripts": {
    "start": "parcel index.html",
    "build": "parcel build --public-url . index.html"
  }
}

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