Export true curves from a geodatabase to a shapefile

Summary

When true curves are created in a geodatabase at a very large scale, they often come across as triangular shapes once converted to shapefile format.

Instructions provide code for converting polygon geodatabase features containing true curves to shapefile features using a method that helps maintain the shape of the true curve.

Procedure

1. Start ArcMap.
2. Open the Visual Basic Editor.
   
   
   In ArcMap, select Tools > Macros > Visual Basic Editor.
   
   
3. In the Project Explorer window, expand Project.mxt and select ArcMap Objects > ThisDocument and right-click to select View Code.
   
   

   Note:
   Code in the Project's ThisDocument code module will only run in the current map document.  If you want to store the code in all your map documents open the Normal.mxt ThisDocument code module instead.

   
   
4. Paste the following code into the code module.
   
   

   Code:
   Sub ExportTrueArcs2Shapefile()
   
   Dim pDoc As IMxDocument
   Dim pFlayerGDB As IFeatureLayer
   Dim pFCursor As IFeatureCursor
   Dim pFeature As IFeature
   Dim pFlayerShape As IFeatureLayer
   Dim pFlayerShapeFC As IFeatureClass
   Dim pPolycurve As IPolycurve2
   Dim dPi As Double
   Dim dMaxSeg As Double
   Dim pGeometry As IGeometry
   Dim dXyUnit As Double
   Dim dXfalse As Double
   Dim dyFalse As Double
   Dim pSPRef As ISpatialReference
   Dim pSegCol As ISegmentCollection
   Dim bNonLinear As Boolean
   Dim pCurve As ICurve
   
   Set pDoc = ThisDocument
   Set pFlayerGDB = pDoc.FocusMap.Layer(0)
   Set pFCursor = pFlayerGDB.FeatureClass.Search(Nothing, False)
   Set pFeature = pFCursor.NextFeature
   
   If pFlayerGDB.FeatureClass.ShapeType <> esriGeometryPolygon _
         Then Exit Sub
   
   Set pFlayerShape = pDoc.FocusMap.Layer(1)
   Set pFlayerShapeFC = pFlayerShape.FeatureClass
   
   'Get the angle in radians
   dPi = Atn(1) * 4
   
   Set pGeometry = pFeature.ShapeCopy
   Set pSPRef = pGeometry.SpatialReference
   pSPRef.GetFalseOriginAndUnits dXfalse, dyFalse, dXyUnit
   
   dMaxSeg = (1 / dXyUnit) * 100000
   While Not pFeature Is Nothing
     Set pCurve = pFeature.Shape
     Set pPolycurve = pCurve
     Set pSegCol = pPolycurve
     pSegCol.HasNonLinearSegments bNonLinear
       If bNonLinear Then
         pPolycurve.DensifyByAngle dMaxSeg, dPi / 180
       End If
     storeFeature pPolycurve, pFlayerShapeFC
     Set pFeature = pFCursor.NextFeature
   Wend
   End Sub
   
   Private Sub storeFeature(pGeo As IGeometry, pFClass As _
        IFeatureClass)
      On Error GoTo errHand
         Dim pNewFCursor As IFeatureCursor
         Dim pFeatureBuffer As IFeatureBuffer
         
         Set pNewFCursor = pFClass.Insert(True)
         Set pFeatureBuffer = pFClass.CreateFeatureBuffer
         Set pFeatureBuffer.Shape = pGeo
         pNewFCursor.InsertFeature pFeatureBuffer
         pNewFCursor.Flush
      Exit Sub
   errHand:
      Debug.Print Err.Description
   End Sub

   
   
5. Close the Visual Basic Editor.
6. Add the polygon geodatabase feature class containing the true curves to ArcMap.
7. Add an empty polygon or polyline shapefile to ArcMap. The features in the geodatabase feature class will be converted and loaded into the shapefile feature class.
8. Make sure the geodatabase feature class is the first layer listed in the Table of Contents and that the shapefile is second.
9. Run the code.
   
   
   A. Click Tools > Macros > Macros to display the Macros dialog box.
   B. Select a macro and click Run.