ArcEngine中最短路径的实现

1、ArcEngine中最短路径的实现最短路径分析属于ArcGIS的网络分析范畴。而ArcGIS的网络分析分为两 类，分别是基于几何网络和网络数据集的网络分析。它们都可以实现最短路径功能。 下面先介绍基于几何网络的最短路径分析的实现。以后会陆续介绍基于网络数据集的 最短路径分析以及这两种方法的区别。几何网络是一种特殊的特征要素类，由一系列不同类别的点要素和线要素（可以度 量并能图形表达）组成的，可在FeatureDataset下面创建，可进行图形与属 性的 编辑。包括流向分析和追踪分析两大功能。主要接口是ITraceFlowSolver。我们先 在一幅地图上做出一个几何网络才能进行最短路径分析。下

2、面是主要的一些步骤：1、打开ArcCatalog ,连接到包含地图的文件夹。2、在空白处，右键新建一个“ Personal GeoDatabase ”。3、在生成的 Personal GeoDatabase 上右键新建一个 feature dataset o4、双击 Personal GeoDatabase jfii,找到刚才 new 出的 feature dataset ,右键 Import导入Feature Class （Single）,选择要建立几何网络的图层或者shape文 件。5、然后再右键新建一个Geometric Network ,选择从已存在的图元中建立几何 网 络。6 打开

3、ArcMap,把刚才建立的 “ Personal GeoDatabase Feature Class ” 添加 到地 图中，这样几何网络就建立好了。这样我们就建立好一个几何网络了。我们现在要通过编程来实现最短路径，用到 的接口主要有 INetworkCollection , IGeometricNetwork , IPointT。日D , ITraceFlowSolverGEN （它实现 了 ITraceFlowSolver 的接口），INetSchema, EIDHelpero主要步骤如下:1、获取几何网络工作空间2、定义一个边线旗数组，把离点串最近的网络元素添加进数组3、设置开始和结束边线

4、的权重4、进行路径分析5、得到路径分析的结果上次介绍了用几何网络实现的“最短路径”，这次用网络数据集实现真正的最短 路径功能，跟上次一样，先处理下数据。1、先打开ArcCatalog,连接到目标文件夹，假定该文件下有一个名为road的道路图层。Cgtents Previ ew Met ad ata INameml Adm_iAjrea_regi on shp "2"AdmALandm ark_p 01 nt r slip AAGreenBel t_regi oxi. shp.inAdLandm ark_point. shp Landus e j> olyl i na.

5、 shp Landnse_r egi on. Ahp o ad_p olyl i ne. whp Ar.lFOI point, shphl Rai 1W SUH 01yLi P-g-B hp绘数据集I Typg Shape file Shape： £il * Shapefile Map document Shapefile Shap&file!ShapefileShap&fileShapefile Sh 斗 p e： "总2、在road图层上右键新建一个网络数据集，并按照其默认设置直至完成庵 CopyX DelateCtrl+CRenameF2Create

6、La2er. .ExportNew Network Dataset.IdrContents Previ ew Metadata U4JH4lAl Adni_Are=a_regi on wh* 2LJ AdirALandm ark_p 0 i nt. shpGrt_regi©n. shp JlAhefei. mxdI Landm ark point, shp " Landus e_p olyl i ne a shp 03 Landus ®_r 皂 on. mhp adjpolyline, shp A*IFOI j>oint. shp ”八Tl Rai 1 Wa

7、y_polylin 电.shp 耳Jir og-uhpProperties.I Type ShapefileShapefileShape file Map DocumentShapefi 1 色Shapefile ShapefileShapefile ShapefileShape filer oad ND. MD网络数据集 Shap&file Network Dataset siiavfiid3、打开该地图的工作空间，把刚才新建的网络数据集添加工作空间中Add DataLook in:，最短路径网络数据集3但I葡I后蠢圈Iroad_ND NDAdni_Area_regi on. shp

8、Adm_Landmark_point. shpGreeriEelt_region. shpMroad. shp圆Iroad ND Junctions. shpLandmark point. shprHLandus«_polyline. shpLanduse_regi on. shp mainroad_polyline shp|P0I point. shpZJ"1 Railway polyline, shpName:|road_ND.NDShow M type: |Datasets and Layers4、在网络分析菜单中选择新建最近设施点Geastati stical Ar

9、ualystGr aphi cLabeling7 LayoutNAp CacheMyToolb&rPubliEh&rRaster PaintiiigR«preseikt&ti onRo-ute E di tingSmpl 电 Ex tens! on ToolbarS chemati cNew gouteNew Servi ce AreaNew Closest Facili tyMew OD Cost H&trixNew Conne 匚OptI OTLE.hefei.axd - Arclap - ArcinfoFile Edi t Vi ew Inser

10、t Selection Tools Window Help田国昌/鼬第x|也通eNetwork Analyst .1:3,411'：Q ：.sJ U44 H<4Network Dataset：X金五里墩邮江淮仪表厂Jj3 0c 回回眄因园E3团旧团|iow jJ I 0Closest Facility最短路径分析图层Facilities Error 。Located?O Unlocated 0 Incidents1 ErrorBB Located ?| |Unlocated 0 BarriersO ErrorLocated? Unlocated-0 Routes Routesro

11、ad_ND JunctionsP0I_pointAdm_L«indm w k_p 01ntLandm arkoint roadroad_NDEdgesRailWay-polyline lay>mainro ad_p olyl i neroad_polyline layerLanduse_polyli neGreenBelt_regi onLanduse_region layerAdm Ayaa r finNJ >Display I Source Selection |Drawing 五里量三I |10 二JB Z U 4 8这时在工作空间里，可以看到多了一个名为“ Clo

12、sest Facility "的图层。它下面还有4个子图层，名字分别为 “Facilities "，"Incidents ",“ Barriers "，“ Routesv Facilities ”就是设施点图层，也就是目的点，uIncidents ”的意思就是出发点，“ Barriers n是障碍点，意思就是地图某条道 路附近有一个障碍点，如果障碍点与道路距离在容限范围内，则表示此道路不通，“Routes”就是最终的结果。这样我们编程实现最短路径的思路就出现了 ：1、 添加出发点。2、 添加目的点。3、生成最优路径，获取结果百。3 ©

13、 ：； ： a Q射 卜0 添加 晦 刷新 平移M赊最短路及安徽省医药学校这里的添加出发点或者目的点，是往“ Facilities "或"Incidents ”图层上添 加元素。获取结果也是从“ Routes"中获取Polyline。往“ Facilities "或“In cide nts ”图层上添加元素用到的主要方法是INALocator的QueryLocationByPoint函数，生成路径主要接口是INASolver和它的Solve方 法。获取结果是按属性查找，因为“ Routes ”类其实就是一个图层类，只不过只是存在于内存。1 CMapCon

14、trolDefaultm_map;2 IPointCollectionPtr mJpPointCollection;33 ILayerPtr ipLayer = m_map.GetLayer(O);/ 网络数据集4 INALayerPtr ipNaLayer = ipLayer;5 if (NULL = ipNaLayer)6 7 return;8 )1011 INAContextPtr ipNaContext;12 HRESULT hr = ipNaLayer->get_Context(&ipNaContext);13 INACIassLoaderPtr ipNACIassLo

15、ader(CLSID_NACIassLoader);14 INALocatorPtr ipNALocator = NULL;15 hr = ipNaContext->get_Locator(&ipNALocator);16 ipNALocator->put_SnapToleranceUnits(esriMeters);17 ipNALocator->put_SnapT olerance(200);18 ipNaContext;19 hr = ipNACIassLoader->putref_Locator(ipNALocator);2020 INamedSetPt

16、r ipNamedSet = NULL;21 ipNaContext->get_NACIasses(&ipNamedSet);2322 CString szName = "Facilities"23 BSTR bstrName = szName.AllocSysString();24 INACIassPtr ipNAFacilitiesClass = NULL;25 hr = ipNamedSet->get_ltemByName(bstrName,(IUnknown*)&ipNAFacilitiesClass);26 szName = "

17、;Incidents”；27 bstrName = szName. AllocSysString();28 INACIassPtr ipNAIncidentsClass = NULL;29 hr = ipNamedSet->get_ltemByName(bstrName,(IUnknown*)&ipNAIncidentsClass);30 szName = nCFRoutesH;31 bstrName = szName. AllocSysString();32 INACIassPtr ipNARoutesClass = NULL;33 hr = ipNamedSet->ge

18、t_ltemByName(bstrName,(IUnknown*)&ipNARoutesClass);3634 INALocationPtr ipNALocationl (CLSID_NALocation);35 INALocationPtr ipNALocation2(CLSID_NALocation);36 ipNACIassLoader->get_Locator(&ipNALocator);37 IPointPtr ipBeginPoint(CLSID_Point);38 m_ipPointCollection->get_Point(0, &ipBeg

19、inPoint);39 IPointPtr ipEndPoint(CLSID_Point);40 mJpPointCollection->get_Point(1, &ipEndPoint);41 IPointPtr ipPointl (CLSID_Point);42 IPointPtr ipPoint2(CLSID二Point);&ipNALocation1,&ipNALocation2,43 double dbLVal = 0.0;44ipNALocator->QueryLocationByPoint(ipBeginPoint,&ipPoint1,

20、 &dbLVal);45ipNALocator->QueryLocationByPoint(ipEndPoint,&ipPoint2, &dbLVal);4950 INALocationObjectPtr ipNALocationObject = NULL;51 IFeatureClassPtr ipFeatureClass = ipNAIncidentsClass;52 IFeaturePtr ipFeature = NULL;53 ipFeatureClass->CreateFeature(&ipFeature);54 IRowSubtypesP

21、tr ipRowSubtypes = ipFeature;55 ipRowSubtypes->lnitDefaultValues();56 ipFeature->putref_Shape(ipBeginPoint);57 ITablePtr ipTable = NULL;58 ipFeature->get_T able(&ipT able);59 long nlndex = 0;60 szName = "Sequence"61 bstrName = szName.AllocSysString();62 ipTable->FindField(b

22、strName, &nlndex);63 VARIANT varjnt;64 varJVal = 1;65 varjnt.vt = VTJNT;66 ipFeature->put_Value(nlndex, varjnt);67 szName = "Name"68 bstrName = szName. AllocSysString();69 ipTable->FindField(bstrName, &nlndex);70 ipFeature->put_Value(nlndex, COIeVariant(nStart Point&

23、quot;);71 ipNALocationObject = ipFeature;72 ipNALocationObject->put_NALocation(ipNALocation1);73 ipFeature->Store();74 IFieldsPtr ipFields(CLSID_Fields);75 hr = ipTable->get_Fields(&ipFields);76 long nFieldCount = 0;77 hr = ipFields->get_FieldCount(&nFieldCount);78 for (int k = 0

24、; k < nFieldCount; k+)79 80 IFieldPtr ipField(CLSID_Field);81 ipFields->get_Field(k, &ipField);82 BSTR bstrFieldName;83 ipField->get_Name(&bstrFieldName);84 CString szFieldName = bstrFieldName;85 8687 ipFeatureClass = ipNAFacilitiesClass;88 ipFeatureClass->CreateFeature(&ipFe

25、ature);89 ipRowSubtypes = ipFeature;90 ipRowSubtypes->lnitDefaultValues();91 ipFeature->putref_Shape(ipEndPoint);92 ipTable = NULL;93 ipFeature->get_T able(&ipT able);94 nlndex = 0;95 szName = "Sequence”；96 bstrName = szName. AllocSysString();97 ipTable->FindField(bstrName, &

26、;nlndex);98 varJVal = 2;99 ipFeature->put_Value(nlndex, varjnt);100 szName = "Name"101 bstrName = szName. AllocSysString();102 ipTable->FindField(bstrName, &nlndex);103 ipFeature->put_Value(nlndex, COIeVariant("End Point1');104 ipNALocationObject = ipFeature;105

27、 ipNALocationObject->put_NALocation(ipNALocation2);106 ipFeature->Store();107108 INACIosestFacilitySolverPtr ipNACFSolver = NULL;109 INASolverPtr ipNASolver = NULL;110 ipNaContext->get_Solver(&ipNASolver);111112 IGPMessagesPtr ipGPM(CLSID_GPMessages);113 ITrackCancelPtr ipTrackCancel(CL

28、SID TrackCancel);114 VARIANT_BOOL blsPartialSolution;115 ipNASolver->Solve(ipNaContext, ipGPM, ipTrackCancel,&blsPartialSolution);116117 szName = nCFRoutes"118 bstrName = szName.AllocSysString();119 ipNARoutesClass = NULL;120 hr = ipNamedSet->getJtemByName(bstrName,(IUnknown*)&ipN

29、ARoutesClass);121122 IFeatureClassPtr ipFeatureClassRoutes = ipNARoutesClass;IFeatureCursorPtr ipFCursor = NULL;IQueryFilterPtr ipQueryFilter(CLSID_QueryFilter);CString szQueryFilter("ObjectlD > 0n);BSTR bstr_QueryFilter = szQueryFilter.AllocSysString();ipQueryFilter->put_WhereClause(bstr_QueryFilter); VARIANT_BOOL bCycle =VARIANT_FALSE;try ipFeatureClassRoutes