[vtkusers] converting a tree stored in vtkGraph into vtkTree (or creating a loop walk through a tree)

[Dr. Roman Grothausmann]

Dear Jeff,


Many thanks for Your reply. I had come across vtkTreeBFSIterator but since that 
only takes an already existent tree as input, I deemed this not to be the right 
method for my task.
Now I wonder what the difference is between vtkTreeBFSIterator and 
vtkBoostBreadthFirstSearchTree?
Perhaps it would be sensible to mention each other method in their docs. I had 
searched for BFS, therefore it did not hit BreadthFirstSearch:-(

Thanks again for Your help
Roman

On 24/01/13 15:55, Jeff Baumes wrote:
> If you have a vtkGraph, you can convert it to a vtkTree with
> vtkBoostBreadthFirstSearchTree. Then you can probably use the tree iterators do
> make the path you desire.
>
> Jeff
>
>
> On Fri, Jan 18, 2013 at 2:49 PM, Dr. Roman Grothausmann
> <grothausmann.roman at mh-hannover.de <mailto:grothausmann.roman at mh-hannover.de>>
> wrote:
>
>     Dear mailing list members,
>
>
>     Now that I have managed to convert vtkPolyData (which represents a tree, the
>     root node position is known) to a vtkGraph (thanks to David Doria's
>     vtkPolyDataToGraph: https://github.com/daviddoria/__VTK-GraphConversions
>     <https://github.com/daviddoria/VTK-GraphConversions>)
>     I'm now facing the problem how to convert the tree that is contained in the
>     vtkGraph into a vtkTree?
>     In the docs it is said that a tree can only be created via
>     vtkMutableDirectedGraph, so guess I need to traverse the vtkGraph in a way
>     that the traversal yields a tree and during traversal a
>     vtkMutableDirectedGraph needs to be created.
>     But how to traverse the graph? In the docs it says that vtkTreeDFSIterator
>     would iterate through a graph but it inherits vtkTreeIterator and only has a
>     method setTree (no setGraph).
>     Is there any other way to tell a PC that a graph is actually a tree if it is
>     told where the root node is?
>
>     My final goal is to create a vtkPolyData that represents the path walked by
>     e.g. a person that starts walking along the tree from the root, visiting
>     every node along a branch till it reaches its end, then goes back to the
>     next branching node (i.e. parent node with more than one child) and then
>     goes an like that until it comes back to the root. The person should then
>     have visited each node at least twice except end-nodes. If the start and the
>     end point of the path are connected the result would be a directed loop.
>     The result could be created very easily by duplicating the initial
>     vtkPolyData and joining the two at each end-node, only the joints needed at
>     the branching-nodes give trouble.
>
>     Any help or hints is very much appreciated
>     Roman
>
>
>     --
>     Dr. Roman Grothausmann
>
>     Tomographie und Digitale Bildverarbeitung
>     Tomography and Digital Image Analysis
>
>     Institut für Funktionelle und Angewandte Anatomie, OE 4120
>     Medizinische Hochschule Hannover
>     Carl-Neuberg-Str. 1
>     D-30625 Hannover
>
>     Tel. +49 511 532-9574 <tel:%2B49%20511%20532-9574>
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-- 
Dr. Roman Grothausmann

Tomographie und Digitale Bildverarbeitung
Tomography and Digital Image Analysis

Institut für Funktionelle und Angewandte Anatomie, OE 4120
Medizinische Hochschule Hannover
Carl-Neuberg-Str. 1
D-30625 Hannover

Tel. +49 511 532-9574