ArcGIS API For JavaScript利用GP服务生成等值线、等值面

继上文 arcgis api for javascript 利用gp服务生成等值线、等值面（一）之生成等值面说了等值线的建模，这次说一下等值面。

二、等值面

2.1 建模

准备环境和用到的插值算法之前说过就不再赘述了，下面直接上图：

主要思路是利用栅格计算器raster calculator提前对栅格值进行归类，再通过栅格转面工具将栅格转成矢量。下面来具体看一下idw和栅格计算器工具。

idw工具：

和生成等值线的工具一样，无需刻意设置什么，output cell size表示生成的像元大小，是自动生成的，也可以自己设置。实际运行过程中，发现这里设置的像元越小，生成的栅格像素精度越高，转出的矢量越准确（通过和同等数据源的等值线对比），当然还要考虑运行效率的问题，可以选一个效率高且能保证精度的数值。

栅格计算器：

这里需要详细说明下：

1.普通的连线是无法连接栅格和栅格计算器工具的，对于栅格计算器的说明可以点击这里，在官方文档里可以看到rastercalculator (expression, output_raster)是没有输入栅格的参数的。我们打开拖入模型的栅格计算器工具，发现输入中已经存在了当前模型内的所有栅格文件，输入有了，那如何才能通过连线才能确保流程准确性呢？查看帮助文档，在“环境”中可以看到“捕捉栅格”

点击可以看到，捕捉栅格的目的是为了让输出栅格与捕捉栅格像元大小一致，那么可以这样连线：

这样就可以了！

2.栅格计算器有点类似于字段计算器，双击列表里要计算的栅格，可以自动生成表达式，再说一下con(a,b,c)这个函数，类似于三元运算符，a如果true，执行b，如果为false，执行c。

下面是根据10、25、50、100、200重新计算栅格的表达式示例：

con("%outputint%" <= 0,0,con("%outputint%" < 10,1,con("%outputint%" < 25,11,con("%outputint%" < 50,26,con("%outputint%" < 100,51,con("%outputint%" < 200,101,201))))))

这样运行模型，设置显示标注，就能查看到效果了：

这样发布即可，发布过程可参考等值线。

js代码参考如下：

require([
"esri/map",
"esri/layers/arcgistiledmapservicelayer",
"esri/layers/arcgisdynamicmapservicelayer",
"esri/geometry/point",
"esri/spatialreference",

"esri/layers/imageparameters",
"esri/symbols/simplemarkersymbol",
"esri/symbols/textsymbol",
"esri/layers/labelclass",
"esri/renderers/simplerenderer",
"esri/layers/featurelayer",
"esri/color",
"esri/symbols/simplelinesymbol",
"esri/layers/graphicslayer",
"esri/graphic",
"esri/tasks/featureset",
"esri/geometry/geometryengine",
"esri/tasks/geoprocessor",
"dojo/domready!"],
function(map, arcgistiledmapservicelayer,arcgisdynamicmapservicelayer, point, spatialreference,
	 imageparameters,simplemarkersymbol,textsymbol, labelclass,simplerenderer,featurelayer,color,simplelinesymbol,graphicslayer,graphic,featureset,geometryengine,geoprocessor) {
	var map = new map("map", {
	//                        center: new point(1.3091608700115489e7, 4273624.108445918, new spatialreference({ wkid: 3857 })),
		autoresize:true,
		sliderstyle: "small",
		logo: false,
		showlabels : true
	});
	var basespatialref = new spatialreference({"wkt":'geogcs["wgs 84",datum["wgs_1984",spheroid["wgs 84",6378137.0,298.257223563]],primem["greenwich",0.0],unit["degree",0.0174532925199433]]'});

	var tiled = new arcgisdynamicmapservicelayer("https://localhost:6080/arcgis/rest/services/sishui/sishuifeature/mapserver");
	map.addlayer(tiled);


	var gp = new geoprocessor("https://localhost:6080/arcgis/rest/services/test/dengzhimian/gpserver/dengzhimian");
	//var gp = new geoprocessor("https://localhost:6080/arcgis/rest/services/test/dengzhimian2/gpserver/dengzhimian2");

	var graphiclayer = new graphicslayer({id:"dian"});
	var sssym = new simplemarkersymbol({
		"color": [255,255,255,64],
		"size": 12,
		"angle": -30,
		"xoffset": 0,
		"yoffset": 0,
		"type": "esrisms",
		"style": "esrismscircle",
		"outline": {
			"color": [0,0,0,255],
			"width": 1,
			"type": "esrisls",
			"style": "esrislssolid"
		}
	});
	var features = [];
	var graphic1 = new graphic(new point(117.320358,35.725506,basespatialref),sssym,{"zvalue":10});
	var graphic2 = new graphic(new point(117.251434,35.699341,basespatialref),sssym,{"zvalue":30});
	var graphic3 = new graphic(new point(117.522662,35.618930,basespatialref),sssym,{"zvalue":400});
	var graphic4 = new graphic(new point(117.275685,35.564684,basespatialref),sssym,{"zvalue":28});
	var graphic5 = new graphic(new point(117.447444,35.755972,basespatialref),sssym,{"zvalue":70});
	var graphic6 = new graphic(new point(117.155146,35.627075,basespatialref),sssym,{"zvalue":100});
	var graphic7 = new graphic(new point(117.404478,35.651812,basespatialref),sssym,{"zvalue":0});
	var graphic8 = new graphic(new point(117.105020,35.770945,basespatialref),sssym,{"zvalue":180});
	//显示数据源，用于展示等值面效果
	graphiclayer.add(graphic1);
	graphiclayer.add(graphic2);
	graphiclayer.add(graphic3);
	graphiclayer.add(graphic4);
	graphiclayer.add(graphic5);
	graphiclayer.add(graphic6);
	graphiclayer.add(graphic7);
	graphiclayer.add(graphic8);
	map.addlayer(graphiclayer);
	
	//组装输入参数
	features.push(graphic1);
	features.push(graphic2);
	features.push(graphic3);
	features.push(graphic4);
	features.push(graphic5);
	features.push(graphic6);
	features.push(graphic7);
	features.push(graphic8);

	var featureset = new featureset();
	featureset.features = features;
	var para = {
		inputpoints:featureset,
		zvalue:"zvalue"
//      clipfeature:"xian1"
	}

	//生成矢量等值面
		gp.submitjob(para,function(result){
			var miangraphiclayer = new graphicslayer({id:"dengzhimian"});
			var symbol = new esri.symbol.simplefillsymbol();
			symbol.setcolor(new dojo.color([150,150,150,0.5]));
			var renderer = new esri.renderer.classbreaksrenderer(symbol, "gridcode");//根据输出矢量的gridcode字段分类渲染
			renderer.addbreak(1,9,new esri.symbol.simplefillsymbol().setcolor(new dojo.color([56, 168, 0,0.5])));
			renderer.addbreak(10,24,new esri.symbol.simplefillsymbol().setcolor(new dojo.color([139, 209, 0,0.5])));
			renderer.addbreak(25,49,new esri.symbol.simplefillsymbol().setcolor(new dojo.color([255,255,0,0.5])));
			renderer.addbreak(50,99,new esri.symbol.simplefillsymbol().setcolor(new dojo.color([255,128,0,0.5])));
			renderer.addbreak(100,199,new esri.symbol.simplefillsymbol().setcolor(new dojo.color([255,128,0,0.5])));
			renderer.addbreak(200,infinity,new esri.symbol.simplefillsymbol().setcolor(new dojo.color([255,0,0,0.5])));
			miangraphiclayer.setrenderer(renderer);

			var jobid = result.jobid;
			var status = result.jobstatus;
			if(status == esri.tasks.jobinfo.status_succeeded) {
				//成功之后，将其中的结果取出来，当然这也是参数名字。
				//在模型中，想要取出中间结果，需要设置为模型参数
				gp.getresultdata(jobid, "output", function(jobinfo){
					var features = jobinfo.value.features;
					dojo.foreach(features,function(graphic){
						miangraphiclayer.add(graphic);
					});
					map.addlayer(miangraphiclayer);
				});
			}
		});
});

这个服务是之前发布的，当时idw的像元大小采用的默认值，并不是上面idw图片中的数值，因此代码结果和arcmap运行结果有点出入，正常发布的话是不会有问题的，当然，这也侧面说明了idw像元大小的设定很有必要，它决定了生成等值面的质量，下面看图：