按多边形边界裁切栅格数据[转]

 Dim aa As IMxDocument
     Set aa = ThisDocument
     Dim pMap As IMap
     Set pMap = aa.FocusMap
    
     Dim pRL As IRasterLayer
     Dim pFL As IFeatureLayer
    
     Set pRL = pMap.Layer(1)
     Set pFL = pMap.Layer(0)
    
     Dim pFCsr As IFeatureCursor
     Dim pFt As IFeature
     Set pFCsr = pFL.FeatureClass.Search(Nothing, False)
     Set pFt = pFCsr.NextFeature
    
     Private m_extraction As IExtractionOp
     Set m_extraction = New RasterExtractionOp
    
     Dim ppp As IGeoDataset
''     set ppp =
     Set ppp = m_extraction.Polygon(pRL.Raster, pFt.Shape, True)
    
     Dim ccc As IRasterLayer
     Set ccc = New RasterLayer
     ccc.CreateFromRaster ppp
    
     pMap.AddLayer ccc