openlayers3

博客提供了OpenLayers官网的访问链接http://openlayers.org/ ,OpenLayers常用于可视化相关开发。
访问 http://openlayers.org/
OpenLayers 3 allows you to create stunning web mapping and WebGIS applications. It uses modern, cutting edge browser technologies. It is written with Closure Library, enabling you to build browser-independent applications without painful debugging ceremonies, which even have some limited fallback options for older browsers. With this guide, you will be introduced to the world of advanced web mapping and WebGIS. First, you will be introduced to the advanced features and functionalities available in OpenLayers 3. Next, you will be taken through the key points of creating custom applications with OpenLayers 3. You will then learn how to create the web mapping application of yours (or your company’s) dream with this open source, expense-free, yet very powerful library. We’ll also show you how to make amazing looking thematic maps and create great effects with canvas manipulation. By the end of this book, you will have a strong command of web mapping and will be well on your way to creating amazing applications using OpenLayers 3. What you will learn Use the advanced functionality of the OpenLayers 3 library effectively Implement the library in your application, shaping it to your needs Manage layers and the layer stack dynamically Create not only stunning but also accurate thematic maps Extend OpenLayers 3 with your own custom classes Develop mobile-friendly web mapping applications Make stunning effects with canvas manipulation, or visualize point clouds with WebGL Integrate third-party applications, and create custom builds that completely satisfy your needs
### OpenLayers 3D 开发概述 OpenLayers本身主要专注于二维地图的渲染和操作,但它可以通过与其他库(如Cesium)集成来实现三维地图的功能。通过这种方式,开发者能够利用OpenLayers强大的交互能力和Cesium卓越的3D渲染能力。 以下是基于OpenLayers与Cesium结合的一个简单示例[^4]: ```javascript // 加载 Cesium 地图引擎 var viewer = new Cesium.Viewer('cesiumContainer', { terrainProvider : Cesium.createWorldTerrain() }); // 定义一个简单的 GeoJSON 数据源作为矢量图层 var vectorSource = new ol.source.Vector({ url: 'https://openlayers.org/en/v6.5.0/examples/data/geojson/countries.geojson', format: new ol.format.GeoJSON() }); // 创建 OpenLayers 图层并设置样式 var vectorLayer = new ol.layer.Vector({ source: vectorSource, style: new ol.style.Style({ stroke: new ol.style.Stroke({ color: '#ffcc33', width: 2 }), fill: new ol.style.Fill({ color: 'rgba(255, 204, 51, 0.4)' }) }) }); // 初始化 OpenLayers 地图实例 var map = new ol.Map({ layers: [ new ol.layer.Tile({ source: new ol.source.OSM() }), vectorLayer ], target: 'map', view: new ol.View({ center: ol.proj.fromLonLat([0, 0]), zoom: 2 }) }); // 同步 OpenLayers 和 Cesium 的视图状态 function syncView() { var view = map.getView(); var resolution = view.getResolution(); var rotation = view.getRotation(); // 获取当前中心点经纬度 var center = view.getCenter(); var lonlat = ol.proj.toLonLat(center); // 转换为 Cesium 所需的笛卡尔坐标系 var cartographic = Cesium.Cartesian3.fromDegrees(lonlat[0], lonlat[1]); viewer.camera.setView({ destination: cartographic, orientation: { heading: Cesium.Math.toRadians(rotation), pitch: -Cesium.Math.PI_OVER_TWO } }); } // 绑定事件监听器以同步视图变化 map.on('moveend', function () { syncView(); }); syncView(); // 初始同步 ``` 此代码片段展示了如何将OpenLayers的地图控件与Cesium的3D地球模型相结合。它允许用户在2D模式下浏览地图的同时,在另一个窗口中查看对应的3D场景[^4]。 #### 关键技术要点说明 - **Cesium 集成**:由于OpenLayers不原生支持3D功能,因此通常会引入第三方库Cesium来进行扩展。 - **GeoJSON 支持**:上述例子加载了一个标准的GeoJSON文件,并将其展示为可自定义样式的矢量图层。 - **视角同步机制**:为了保持用户体验的一致性,实现了两个不同维度视图之间的实时更新逻辑。 ###
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