public TinNode Current {get;}

{
  // search all nodes that intersect the data extent
  using (ArcGIS.Core.Data.Analyst3D.TinNodeCursor nodeCursorsearch = tinDataset.SearchNodes(null))
  {
    while (nodeCursor.MoveNext())
    {
      using (ArcGIS.Core.Data.Analyst3D.TinNode nodeCurrent = nodeCursor.Current)
      {
        // do something with the node
      }
    }
  }

  // search within an extent
  ArcGIS.Core.Data.Analyst3D.TinNodeFilter nodeFilter = new ArcGIS.Core.Data.Analyst3D.TinNodeFilter();
  nodeFilter.FilterEnvelope = envelope; //or use any other appropriate envelope
  using (ArcGIS.Core.Data.Analyst3D.TinNodeCursor nodeCursorSearch = tinDataset.SearchNodes(nodeFilter))
  {
    while (nodeCursor.MoveNext())
    {
      using (ArcGIS.Core.Data.Analyst3D.TinNode nodeCurrent = nodeCursor.Current)
      {
        // do something with the node
      }
    }
  }

  // search all "inside" nodes
  nodeFilter = new ArcGIS.Core.Data.Analyst3D.TinNodeFilter();
  nodeFilter.FilterType = ArcGIS.Core.Data.Analyst3D.TinFilterType.InsideDataArea;
  using (ArcGIS.Core.Data.Analyst3D.TinNodeCursor nodeCursorSearch = tinDataset.SearchNodes(nodeFilter))
  {
    while (nodeCursor.MoveNext())
    {
      using (ArcGIS.Core.Data.Analyst3D.TinNode nodeCurrent = nodeCursor.Current)
      {
        // do something with the node
      }
    }
  }

  // search for super nodes only
  nodeFilter = new ArcGIS.Core.Data.Analyst3D.TinNodeFilter();
  nodeFilter.FilterEnvelope = tinDataset.GetSuperNodeExtent();
  nodeFilter.SuperNode = true;
  using (ArcGIS.Core.Data.Analyst3D.TinNodeCursor nodeCursorSearch = tinDataset.SearchNodes(nodeFilter))
  {
    while (nodeCursor.MoveNext())
    {
      using (ArcGIS.Core.Data.Analyst3D.TinNode nodeCurrent = nodeCursor.Current)
      {
        // do something with the node
      }
    }
  }
}