How to get the nodes on the absolute boundary of a TIN with ArcObjects

Question

I am trying to get only the nodes on the absolute boundary of a Tin. But GetNeighbor or LeftTriangle methods return edges whose nodes have NaN Z and very weird X-Y coordinates, so the row is inserted in the feature class without a feature.

Is there any other method or am I doing anything wrong? Thanks, Mar

Dim i As Integer For i = 1 To pTinAdvC1.TriangleCount

Set pTinTriangleC1 = pTinAdvC1.GetTriangle(i)

    Dim j As Integer
    For j = 0 To 2

        If pTinTriangleC1.Edge(j).GetNeighbor Is Nothing Then

        Dim pTinEdge As ITinEdge
        Set pTinEdge = pTinTriangleC1.Edge(j)

        Dim pBorderP As IPoint
        Set pBorderP = New Point
        Set pZAwarePoint = pBorderP
        pZAwarePoint.ZAware = True

        pTinEdge.FromNode.QueryAsPoint pBorderP

        Set pPointLayer = pScene.Layer(2)
        Set pPointFC = pPointLayer.FeatureClass
        Set pFeat = pPointFC.CreateFeature
        On Error Resume Next
        Set pFeat.Shape = pBorderP
        pFeat.Store

        End If

    Next

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