arcgis for jsapi 4.10绘制热力图

谁借莪１个温暖的怀抱￠ 2022-03-20 14:56 304阅读 0赞

arcgis for jsapi 从 3 变到 4 之后，变化巨大，原先网络上的许多例子，好像都过时了。比如echart与arcgis结合，都是for 3.x的,4时代就不行了。

热力图也一样。

现在俺给个例子，不依赖于arcgis服务器，直接渲染出来：

原理是绘制，绘制在FeatureLayer里。怎么绘制呢？原来热力图有个专门的渲染器：HeatmapRenderer，将样式赋给该渲染器，然后渲染器、点数据等参与FeatureLayer的构造，就可以了。

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2xlZnRmaXN0_size_16_color_FFFFFF_t_70]

<!DOCTYPE html>
    <html>
    <head>
    	<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
    	<meta name="viewport" content="initial-scale=1, maximum-scale=1,user-scalable=no"/>
    	<title>heatMap</title>
    	<link rel="stylesheet" type="text/css" href="http://192.168.0.211/pubzy/arcgis_js_api/4.10/esri/css/main.css" />
    	<style> html, body, #map { height: 100%; margin: 0; padding: 0; } </style>
    	<script src="http://192.168.0.211/pubzy/media/js/jquery-1.11.1.min.js" type="text/javascript"></script>
    	<script src="http://192.168.0.211/pubzy/arcgis_js_api/4.10/init.js"></script>
    </head>
    
    <body>
    	<div id="map"></div>
    </body>
    
    <script> require(["esri/map", "esri/views/MapView", "esri/Basemap", "esri/geometry/Extent", "esri/layers/TileLayer", "esri/layers/FeatureLayer", "esri/renderers/HeatmapRenderer", "dojo/domReady!"], function (Map, MapView, BaseMap, Extent, TileLayer, FeatureLayer, HeatmapRenderer) { let map, view; (function () { //加载底图等 map = new Map({ basemap: getBaseMap({ "title": "影像图", "thumbnailUrl": "images/map/影像图.gif", "type": "tile", "layer": "http://192.168.0.206:6080/arcgis/rest/services/HNJCZS/HNJCZSYXT/MapServer" }), }); view = new MapView({ container: "map", map: map, extent: new Extent({ "xmin": 105, "ymin": 18, "xmax": 115, "ymax": 20, "spatialReference": { "wkid": 4326 } }), }); view.ui._removeComponents(["attribution"]); })(); function getBaseMap(basemapcof) { let baselayer = new TileLayer({ url: basemapcof.layer, }); return new BaseMap({ baseLayers: baselayer, title: basemapcof.title, thumbnailUrl: "../" + basemapcof.thumbnailUrl, }); } var heatmapRenderer = new HeatmapRenderer({ //设置渲染器 colorStops: [{ ratio: 0.4, color: "rgba(0, 255, 0, 0)" }, { ratio: 0.75, color: "rgba(255, 140, 0, 1)" }, { ratio: 0.9, color: "rgba(255, 0, 0, 1)" }], blurRadius: 8, maxPixelIntensity: 230, minPixelIntensity: 10 }); var heatDataUrl = "data/heatJson.json"; $.getJSON(heatDataUrl,{ },function(data,textStatus,jqXHR){ //读取数据，设置点数据集 var features = []; for (var i = 0; i < data.heatData.length; i++) { var x = data.heatData[i].lng; var y = data.heatData[i].lat; features.push({ geometry: { type: "point", x: x, y: y }, attributes: { ObjectID: i,//重要！！！ } }); } var featureLayer = new FeatureLayer({ source: features,//点数据集 title: "热力图", objectIdField: "ObjectID",//重要！！！ renderer: heatmapRenderer//渲染器 }); map.add(featureLayer); }); }); </script>
    </html>

点数据很简单，JSON格式，里面只有经纬度

{"heatData":[{"lng":"108.51293787947446","lat":"18.899562096488552"},{"lng":"108.38702921054004","lat":"19.151761337656723"},。。。。

可以从参考资料里下载  
https://lxqjss.github.io/data/heatJson.json

不过这个位置是杭州的，我改为海南了。海南的可从这里下载：

[海南热力图数据][Link 1]

这下载分是CSDN自动设置的，我的话，一般只设为1。老实说，CSDN好多东西都做的很烂。

热力图有个专有的名词：HeatMap，可以用这个单词去搜。

参考资料：  
[arcgis js api:热力图][arcgis js api]

arcgis for jsapi官网上有两个例子，一个似乎是直接展示图层，一个是依赖于CSVLayer，好像挺复杂。

https://developers.arcgis.com/javascript/latest/sample-code/visualization-heatmap-scale/index.html

https://developers.arcgis.com/javascript/latest/sample-code/visualization-heatmap/index.html

[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2xlZnRmaXN0_size_16_color_FFFFFF_t_70]: /images/20220320/421b2c3a6fd0429b90ab7fa65ccf3063.png
[Link 1]: https://download.csdn.net/download/leftfist/10955939
[arcgis js api]: https://www.jianshu.com/p/3b36a05872e2