geotools获取给定点的DEM高程值

概述

本文讲述结合geotools实现获取给定点的DEM（tif格式）高程值。

需求描述

1、在web端绘制一条曲线；

2、获取各节点处的高程值；

3、根据高程值绘制高程堆积图。

实现效果

实现思路及代码

1、绘制曲线，将绘制的结果传给后台

var draw = new ol.interaction.Draw({source: source,type: "LineString",freehand: false//是否手绘});map.addInteraction(draw);draw.setActive(false);draw.on("drawend", function (evt) {draw.setActive(false);var coords = evt.feature.getGeometry().getCoordinates(),points = [];for(var i=0;i<coords.length;i++){points.push(coords[i].join(","));}$.get("dem/query", {points: points.join(";")}, function (result) {console.info(result);})});

2、后台解析数据并获取点的高程数据

String points_data = request.getParameter("points");String demPath = "/Users/lzugis/Documents/ncdata/bj_dem.tif";File file = new File(demPath);GeoTiffReader tifReader = new GeoTiffReader(file);GridCoverage2D coverage = tifReader.read(null);CoordinateReferenceSystem crs = coverage.getCoordinateReferenceSystem2D();String[] points = points_data.split(";");List list = new ArrayList();for(int i=0;i<points.length;i++) {String strLonlat = points[i];String[] strLonlats = strLonlat.split(",");double lon = Double.parseDouble(strLonlats[0]),lat = Double.parseDouble(strLonlats[1]);DirectPosition position = new DirectPosition2D(crs, lon, lat);int[] results = (int[]) coverage.evaluate(position);results = coverage.evaluate(position, results);Map map = new HashMap();map.put("lon", lon);map.put("lat", lon);map.put("dem", results[0]);list.add(JSONObject.toJSONString(map));response.getWriter().println(JSONArray.toJSONString(list));}

3、前段接受数据并展示

var dom = document.getElementById("chart");var myChart = echarts.init(dom);var option = {title: {text: '高程图'},backgroundColor:"rgba(255, 255, 255, .8)",grid: {left: '5%',right: '4%',bottom: '1%',containLabel: true},xAxis : [{show:false,type : 'category',boundaryGap : false,data : ["点1", "点2", "点3", "点4"]}],yAxis : [{type : 'value',offset:15}],series : [{name: 'DEM',type: 'line',stack: '总量',label: {normal: {show: true,position: 'top'}},areaStyle: {normal: {}},data: [714, 1000, 1063, 864]}]};myChart.setOption(option);

说明：

1、dem数据来源于地理空间数据云

2、展示用echart实现的。

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