ArcEngine中最短路徑的實現(xiàn)

1、ArcEngine中最短路徑的實現(xiàn)最短路徑分析屬于ArcGIS的網(wǎng)絡(luò)分析范疇。而ArcGIS的網(wǎng)絡(luò)分析分為兩 類，分別是基于幾何網(wǎng)絡(luò)和網(wǎng)絡(luò)數(shù)據(jù)集的網(wǎng)絡(luò)分析。它們都可以實現(xiàn)最短路徑功能。 下面先介紹基于幾何網(wǎng)絡(luò)的最短路徑分析的實現(xiàn)。以后會陸續(xù)介紹基于網(wǎng)絡(luò)數(shù)據(jù)集的 最短路徑分析以及這兩種方法的區(qū)別。幾何網(wǎng)絡(luò)是一種特殊的特征要素類，由一系列不同類別的點要素和線要素（可以度 量并能圖形表達）組成的，可在FeatureDataset下面創(chuàng)建，可進行圖形與屬 性的 編輯。包括流向分析和追蹤分析兩大功能。主要接口是ITraceFlowSolver。我們先 在一幅地圖上做出一個幾何網(wǎng)絡(luò)才能進行最短路徑分析。下

2、面是主要的一些步驟：1、打開ArcCatalog ,連接到包含地圖的文件夾。2、在空白處，右鍵新建一個“ Personal GeoDatabase ”。3、在生成的 Personal GeoDatabase 上右鍵新建一個 feature dataset o4、雙擊 Personal GeoDatabase jfii,找到剛才 new 出的 feature dataset ,右鍵 Import導(dǎo)入Feature Class （Single）,選擇要建立幾何網(wǎng)絡(luò)的圖層或者shape文 件。5、然后再右鍵新建一個Geometric Network ,選擇從已存在的圖元中建立幾何 網(wǎng) 絡(luò)。6 打開

3、ArcMap,把剛才建立的 “ Personal GeoDatabase Feature Class ” 添加 到地 圖中，這樣幾何網(wǎng)絡(luò)就建立好了。這樣我們就建立好一個幾何網(wǎng)絡(luò)了。我們現(xiàn)在要通過編程來實現(xiàn)最短路徑，用到 的接口主要有 INetworkCollection , IGeometricNetwork , IPointT。日D , ITraceFlowSolverGEN （它實現(xiàn) 了 ITraceFlowSolver 的接口），INetSchema, EIDHelpero主要步驟如下:1、獲取幾何網(wǎng)絡(luò)工作空間2、定義一個邊線旗數(shù)組，把離點串最近的網(wǎng)絡(luò)元素添加進數(shù)組3、設(shè)置開始和結(jié)束邊線

4、的權(quán)重4、進行路徑分析5、得到路徑分析的結(jié)果上次介紹了用幾何網(wǎng)絡(luò)實現(xiàn)的“最短路徑”，這次用網(wǎng)絡(luò)數(shù)據(jù)集實現(xiàn)真正的最短 路徑功能，跟上次一樣，先處理下數(shù)據(jù)。1、先打開ArcCatalog,連接到目標(biāo)文件夾，假定該文件下有一個名為road的道路圖層。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繪數(shù)據(jù)集I Typg Shape file Shape： £il * Shapefile Map document Shapefile Shap&file!ShapefileShap&fileShapefile Sh 斗 p e： "總2、在road圖層上右鍵新建一個網(wǎng)絡(luò)數(shù)據(jù)集，并按照其默認(rèn)設(shè)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 電.shp 耳Jir og-uhpProperties.I Type ShapefileShapefileShape file Map DocumentShapefi 1 色Shapefile ShapefileShapefile ShapefileShape filer oad ND. MD網(wǎng)絡(luò)數(shù)據(jù)集 Shap&file Network Dataset siiavfiid3、打開該地圖的工作空間，把剛才新建的網(wǎng)絡(luò)數(shù)據(jù)集添加工作空間中Add DataLook in:，最短路徑網(wǎng)絡(luò)數(shù)據(jù)集3但I葡I后蠢圈Iroad_ND NDAdni_Area_regi on. shp

8、Adm_Landmark_point. shpGreeriEelt_region. shpMroad. shp圓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、在網(wǎng)絡(luò)分析菜單中選擇新建最近設(shè)施點Geastati stical Ar

9、ualystGr aphi cLabeling7 LayoutNAp CacheMyToolb&rPubliEh&rRaster PaintiiigR«preseikt&ti onRo-ute E di tingSmpl 電 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田國昌/鼬第x|也通eNetwork Analyst .1:3,411'：Q ：.sJ U44 H<4Network Dataset：X金五里墩郵江淮儀表廠Jj3 0c 回回眄因園E3團舊團|iow jJ I 0Closest Facility最短路徑分析圖層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這時在工作空間里，可以看到多了一個名為“ Clo

12、sest Facility "的圖層。它下面還有4個子圖層，名字分別為 “Facilities "，"Incidents ",“ Barriers "，“ Routesv Facilities ”就是設(shè)施點圖層，也就是目的點，uIncidents ”的意思就是出發(fā)點，“ Barriers n是障礙點，意思就是地圖某條道 路附近有一個障礙點，如果障礙點與道路距離在容限范圍內(nèi)，則表示此道路不通，“Routes”就是最終的結(jié)果。這樣我們編程實現(xiàn)最短路徑的思路就出現(xiàn)了 ：1、 添加出發(fā)點。2、 添加目的點。3、生成最優(yōu)路徑，獲取結(jié)果百。3 ©

13、 ：； ： a Q射 卜0 添加 晦 刷新 平移M賒最短路及安徽省醫(yī)藥學(xué)校這里的添加出發(fā)點或者目的點，是往“ Facilities "或"Incidents ”圖層上添 加元素。獲取結(jié)果也是從“ Routes"中獲取Polyline。往“ Facilities "或“In cide nts ”圖層上添加元素用到的主要方法是INALocator的QueryLocationByPoint函數(shù)，生成路徑主要接口是INASolver和它的Solve方 法。獲取結(jié)果是按屬性查找，因為“ Routes ”類其實就是一個圖層類，只不過只是存在于內(nèi)存。1 CMapCon

14、trolDefaultm_map;2 IPointCollectionPtr mJpPointCollection;33 ILayerPtr ipLayer = m_map.GetLayer(O);/ 網(wǎng)絡(luò)數(shù)據(jù)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