ArcServer 9.3 下线性参考定位的实现。
首先要生成路径（route）数据，然后在路径（route）数据的基础上生成点事件以及线事件。
这样就可以利用esri提供的Imsegmentation接口, 通过Imsegmentation 接口的GetPointsAtM 和GetSubcurveBetweenMs 就可以找到
M 值（里程值）为某一特定值的所有点以及M值在某一特定区间内的线。以下面例子为例,实现的是管线上具有某一里程值（距离管线起始点的管线线上距离）的点的定位。
//连接远程地图服务
ESRI.ArcGIS.ADF.Identity id = new ESRI.ArcGIS.ADF.Identity("Administrator", "123456", "gis2-trq");
ESRI.ArcGIS.ADF.Connection.AGS.AGSServerConnection agsconn;
agsconn = new ESRI.ArcGIS.ADF.Connection.AGS.AGSServerConnection("10.150.38.34", id);
agsconn.Connect();
if (!agsconn.IsConnected)
{
agsconn.Dispose();
return "";
}
//得到对应的地图服务以及对应的featureclass
ESRI.ArcGIS.Server.IServerObjectManager som = agsconn.ServerObjectManager;
string servertype = "MapServer";
string serverobjectname = "LCZ";
ESRI.ArcGIS.Server.IServerContext sc = som.CreateServerContext(serverobjectname, servertype);
IMapServer pMapServer = sc.ServerObject as IMapServer;
IMapServerObjects pMapServerObjs = pMapServer as IMapServerObjects;
IMap pMap = pMapServerObjs.get_Map(pMapServer.DefaultMapName);
IFeatureLayer pFLayer = pMap.get_Layer(2) as IFeatureLayer;
IFeatureClass pFeatureClass = pFLayer.FeatureClass;
ESRI.ArcGIS.Geodatabase.QueryFilter qFilter = sc.CreateObject("esriGeodatabase.QueryFilter") as ESRI.ArcGIS.Geodatabase.QueryFilter;
//mile 为一特定的里程值
qFilter.WhereClause = String.Format("From_M<={0} AND End_M>={1}", mile, mile);
IFeatureCursor fCursor = pFeatureClass.Search(qFilter, true);
IFeature feature;
ESRI.ArcGIS.Geometry.IPolyline polyline = null;
while ((feature = fCursor.NextFeature()) != null)
{
polyline = feature.Shape as ESRI.ArcGIS.Geometry.IPolyline;
}
ESRI.ArcGIS.Geometry.IMSegmentation mseg = null;
ESRI.ArcGIS.Geometry.IPointCollection pColl = null;
//得到 IMSegmentation接口对象
mseg = (ESRI.ArcGIS.Geometry.IMSegmentation)polyline;
double M = mile;
//得到满足里程条件的点集
pColl = mseg.GetPointsAtM(M, 0) as ESRI.ArcGIS.Geometry.IPointCollection;
// projectpoint为一坐标转换函数，将pColl.get_Point(0).X得到的beijing54坐标转换为WGS84经纬度坐标。这样做可能会有误差影响定位结果。
//最好能保持坐标一致，就不用转换了，就不会有误差产生。
ESRI.ArcGIS.Geometry.IPoint pt = projectpoint(pColl.get_Point(0).X, pColl.get_Point(0).Y, false);
ESRI.ArcGIS.ADF.Web.Geometry.Point pSelGeo = new ESRI.ArcGIS.ADF.Web.Geometry.Point(pt.X, pt.Y);
ClearTempElementInMap(map);//清除定位标记
ESRI.ArcGIS.ADF.Web.Geometry.Envelope pEnv = new ESRI.ArcGIS.ADF.Web.Geometry.Envelope(pSelGeo.X - 0.001, pSelGeo.Y - 0.001, pSelGeo.X + 0.001, pSelGeo.Y + 0.001);
map.Extent = pEnv;
AddTempGraphicElement(pSelGeo, false, "", false, System.Drawing.Color.Red, 30, map);//添加定位点标记符号
ESRI.ArcGIS.ADF.Web.UI.WebControls.Toolbar toolbar = (ESRI.ArcGIS.ADF.Web.UI.WebControls.Toolbar)map.Page.FindControl("Toolbar1");
map.CallbackResults.CopyFrom(toolbar.CallbackResults);
return map.CallbackResults.ToString();
