[vtkusers] Distinctive indexes on a vtkPolyData

[Li, Wen]

Hi Hila,

I understand better about your problem now.

You want to group your vertices on a surface according to some distance?
Can you search of a seed vertex(point) with extreme coordinates along one axis (x, or y, or z).
And then use the Euclidean distance to classify vertices?

Maybe the problem you are facing is more complicated than this.

Hope it helps though,
Wen

On May 1, 2012, at 7:49 AM, Hila Hiler wrote:


Hi Wen,
many thanks for your answer.

I've read about kDTree and wondered if the OcTree is better (I have a 3D image).
please detail (if you know) why KdTree is better than OcTree or the opposite ...

regarding my first q:
-------------------------
my data structure:
vtkPolyData <=> vtkFloatArray <=> Scalars

I'm searching for a method that divides the poly to regions (how do I insert the number of the required regions) and returns the indexes (vtkIdType) + its corresponding scalar (float) in each region.

How I can get this?

Best and thanks in advance.
Hila



On Sun, Apr 29, 2012 at 10:32 PM, Li, Wen <wen-li at uiowa.edu<mailto:wen-li at uiowa.edu>> wrote:
Hila,

Is vtkKdTreePointLocator::FindPointsWithinRadius going to help you?

You can exclude points within a specific radius and the rest points on the surface are beyond that value.

You are right about the point ids. neighboring points could have very different point Ids.

Good Luck,
Wen

On Apr 29, 2012, at 2:21 PM, Hila Hiler wrote:

Hi All,

I'd like to get some distant points on a surface (in this case, a head).
How do I know what the distance value should be?

Actually, in my program I use this type: vtkIdType and with a loop move on a vtkPolyData.
I tried to guess a number (5000), presented the points on the surface but realized that even that those points look very close, their indexes are faraway from each other- so I guess that I don't have a clue about it :-)


so, any idea how I should find indexes/points which are faraway from each other on a surface ?


Thanks in advance.

Hila
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