LeaFlet学习之结合turf.js生成简单的等值线demo
本文主要结合turf.js生成等值线俺，进行展示效
一、放张图：
二、全部源码
<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>等值线的生成</title>
<link href="Script/leaflet/leaflet.css" rel="stylesheet" />
<style>
#map
{
height: 2000px;
width: 1500px;
}
</style>
<script src="Script/leaflet/leaflet.js"></script>
<script src="Script/leaflet/leaflet.ChineseTmsProviders.js"></script>
<script src='https://npmcdn.com/@turf/turf/turf.min.js'></script>
</head>
<body>
<div id="map"></div>
</body>
<script>
var normalm = L.tileLayer.chinaProvider('TianDiTu.Normal.Map', {
maxZoom: 18,
minZoom: 1
}),
normala = L.tileLayer.chinaProvider('TianDiTu.Normal.Annotion', {
maxZoom: 18,
minZoom: 1
}),
imgm = L.tileLayer.chinaProvider('TianDiTu.Satellite.Map', {
maxZoom: 18,
minZoom: 1
}),
imga = L.tileLayer.chinaProvider('TianDiTu.Satellite.Annotion', {
maxZoom: 18,
minZoom: 1
});
var normal = L.layerGroup([normalm, normala]);
image = L.layerGroup([imgm, imga]);
var baseLayers = {
"地图": normal,
"影像": image,
}
var overlayLayers = {
"图": normal,
"像": image,
}
var map = L.map("map", {
center: [31.59, 120.29],
zoom: 12,
layers: [normal],
zoomControl: false
});
// 创建等值线区域
var extent = [0, 30, 20, 50];
var cellWidth = 100;
var pointGrid = turf.pointGrid(extent, cellWidth, { units: 'miles' });
for (var i = 0; i < pointGrid.features.length; i++) {
pointGrid.features[i].properties.temperature = Math.random() * 10;
}
console.log(pointGrid.features.length);
//等值线的级数
var breaks = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10];
var lines = turf.isolines(pointGrid, breaks, { zProperty: 'temperature' });
//设置颜色
var myStyle = {
"color": "#ff7800",
"weight": 5,
"opacity": 0.65
};
//进行平滑处理
var _lFeatures = lines.features;
for(var i=0;i<_lFeatures.length;i++){
var _coords = _lFeatures[i].geometry.coordinates;
var _lCoords = [];
for(var j=0;j<_coords.length;j++){
var _coord = _coords[j];
var line = turf.lineString(_coord);
var curved = turf.bezierSpline(line);
_lCoords.push(curved.geometry.coordinates);
}
_lFeatures[i].geometry.coordinates = _lCoords;
}
//geojson数据读取
L.geoJSON(lines, {
style: myStyle
}).addTo(map);
</script>
</html>
三、总结
这里是等值线，可不是等高线，等高线不会相交，等值线可能相交，数据平滑参考牛老师ol4的等值线效果。
