用程式實現從帶高程的點資料到等高線的轉換

link: http://www.gisempire.com/blog/more.asp?name=gis&id=86

 

內容摘要 從高程點到等高線不是一步實現的，而是先把高程點先插值產生TIN，然後再從TIN產生等高線。在從TIN到等高線的產生過程中8.3和9.0上還有點區別，請看代碼注釋。下面的是整個過程的代碼執行個體。 流程說明 '開啟高程點資料
Dim pFeatureLayer As IFeatureLayer
Set pFeatureLayer = MapControl1.Map.Layer(0)
If pFeatureLayer Is Nothing Then Exit Sub
Dim pFeatureClass As IFeatureClass
Set pFeatureClass = pFeatureLayer.FeatureClass

'產生TIN
Dim pTinEdit As ITinEdit
Dim pTinSurface As ISurface
Dim pTable As ITable
Set pTinEdit = New Tin
Set pTable = New FeatureLayer
pTinEdit.InitNew MapControl1.ActiveView.Extent
Dim pField As IField
Set pField = pFeatureClass.Fields.Field(pFeatureClass.Fields.FindField("Well_Dpth"))
pTinEdit.AddFromFeatureClass pFeatureClass, Nothing, pField, Nothing, 18

Set pTinSurface = pTinEdit

'開啟已經建立好的空的等高線資料(也可以在此時建立一個要素類9，如果是9.0版本的話，在空等高線資料中預先需要建一個欄位來儲存高
'程值，如果是8.3版本的話就不可以預先建立這樣的一個高程欄位，而是在產生等高線過程中根據你指定的
'欄位名稱即時建立
Dim pPropset As IPropertySet
Set pPropset = New PropertySet

Dim pFact As IWorkspaceFactory
Dim pWorkspace As IWorkspace

pPropset.SetProperty "DATABASE", App.Path + "\data\"

Set pFact = New ShapefileWorkspaceFactory
Set pWorkspace = pFact.Open(pPropset, Me.hWnd)

Dim pFeatureWorkspace As IFeatureWorkspace
Set pFeatureWorkspace = pWorkspace

Dim pFeatureClass1 As IFeatureClass
Set pFeatureClass1 = pFeatureWorkspace.OpenFeatureClass("MyShape33")

'產生等高線
pTinSurface.Contour 0, 50, pFeatureClass1, "Well_Dpth", 1

Dim pFLayer As IFeatureLayer
Set pFLayer = New FeatureLayer
Set pFLayer.FeatureClass = pFeatureClass1

MapControl1.AddLayer pFLayer
MapControl1.ActiveView.Refresh