[Insight-users] calculate normal

rashedk rashed.vtk at googlemail.com
Thu Feb 21 14:50:51 EST 2008


Hi, 

In the documentation of ComputeNormal of SimplexMesh it says: 

CovariantVectorType itk::SimplexMesh< TPixelType, VDimension, TMeshTraits
>::ComputeNormal  	(  	unsigned long   	 idx  	 )   	 const

compute the normal vector in the specified mesh point 

I need to pass in the index of the mesh point as a parameter. Which function
returns the index of a mesh point on a simplex mesh?? 

Thanks, 
Rashed



Alex. GOUAILLARD-2 wrote:
> 
> Hi rashed,
> 
> The meshtraits is a list of type definition to finely tune your structure
> depending on your usage. You can read more in the itk software guide:
> Chapter 4.3.4 "Customizing the Mesh", page 70.
> 
> A meshtrait is provided by default, so you can basically ignore that for
> your first experiments and use the itk:SimplexMesh as if it was templated
> only over the PixelType and the Dimension. (Note, the Dimension also has a
> default value, so theoretically, you only need to define a PixelType)
> 
> 
> //----------------- original code
> 
> // NOTE see the default values for Vdimension and TMeshTraits
> template < typename TPixelType,
>            unsigned int VDimension = 3,
>            typename TMeshTraits = DefaultStaticMeshTraits< TPixelType,
>                                                            VDimension,
>                                                            VDimension,
>                                                            TPixelType,
>                                                            TPixelType,
>                                                            TPixelType >
>           >
> class SimplexMesh : public Mesh<TPixelType, VDimension, TMeshTraits>
> 
> 
> //-----------------
> 
> 
> Possible usages:
> 
> // simplest
> Typedef itk::SimplexMesh< float >      MyFirstSimplexMeshType;
> 
> // same thing with second template parameter explicitly set
> Typedef itk::SimplexMesh< float, 3 >   MySecondSimplexMeshType;
> 
> // full options - stay away from that unless you **really** know what you
> do
> Typedef float PointAndCellDataType;
> typedef float                Coord;
> const unsigned int  SDimension = 3; // space dimension
> Const unsigned int  TDimension = 2; // max topological dim. Surface => 2
> 
> typedef itk:: DefaultStaticMeshTraits<
>       PointAndCellDataType,
>       SDimension,  
>       TDimension, 
>       Coord,
>       Coord,
>       PointAndCellDataType           >    MeshTraitsType;
>  
> typedef SimplexMesh< PointAndCellDataType, SDimension, MeshTraitsType >
>                                           MeshType;
> 
> 
> On 2/20/08 10:18 AM, "rashedk" <rashed.vtk at googlemail.com> wrote:
> 
>> 
>> Thanks! 
>> 
>> What is TMeshTraits in itk::SimplexMesh< TPixelType, VDimension,
>> TMeshTraits
>>> ??
>> 
>> What should I pass for TMeshTraits?
>> 
>> 
>> 
>> 
>> Leila Baghdadi-2 wrote:
>>> 
>>> check InsightApplication/DeformableModel...
>>> 
>>> I think that code needs work but I am sure I have the part where it
>>> converts the mesh to pass to vtk.
>>> 
>>> HTH
>>> 
>>> Leila
>>> 
>>> On Wed, 2008-20-02 at 09:21 -0800, rashedk wrote:
>>>> 
>>>> Thanks, but now I am stuck trying to display a simplex mesh in VTK. How
>>>> do I
>>>> visualize this mesh? Is there also a way to iterate through every point
>>>> on
>>>> the mesh?  
>>>> 
>>>> Rashed. 
>>>> 
>>>> 
>>>> Leila Baghdadi-2 wrote:
>>>>> 
>>>>> Yep that's right and another note,
>>>>> 
>>>>> you "must" create a triangle mesh in order to create a simplex mesh!
>>>>> 
>>>>> If you are unsure about how it is done, check the paper
>>>>> simplex mesh
>>>>> by herve delingette of INRIA france
>>>>> 
>>>>> good luck
>>>>> 
>>>>> Leila
>>>>> 
>>>>> On Wed, 2008-20-02 at 12:47 +0100, Iván Macía wrote:
>>>>>> Hi Rashed,
>>>>>> 
>>>>>> You can do what you mention with VTK or directly in ITK use
>>>>>> itk::BinaryMask3DMeshSource, which is the equivalent of Marching
>>>>>> Cubes
>>>> in
>>>>>> ITK. As the name implies, you need a binary mask (segmentation) as
>>>> input.
>>>>>> 
>>>>>> HTH
>>>>>> 
>>>>>> Ivan
>>>>>> 
>>>>>> -----Mensaje original-----
>>>>>> De: insight-users-bounces+imacia=vicomtech.org at itk.org
>>>>>> [mailto:insight-users-bounces+imacia=vicomtech.org at itk.org] En nombre
>>>> de
>>>>>> rashedk
>>>>>> Enviado el: miércoles, 20 de febrero de 2008 12:06
>>>>>> Para: insight-users at itk.org
>>>>>> Asunto: Re: [Insight-users] calculate normal
>>>>>> 
>>>>>> 
>>>>>> Hi, 
>>>>>> 
>>>>>> How do I convert my 3D image data to a simplex mesh in order to
>>>> compute
>>>>>> the
>>>>>> normals? Checking the class documentation for itk::SimplexMesh
>>>>>> reveals
>>>>>> that
>>>>>> one has to generate a triangle mesh and then use the
>>>>>> itkTriangleMeshToSimplexMeshFilter. But then how do I convert my 3D
>>>> image
>>>>>> data to a triangle mesh?? Do I use vtkContour to produce polyData and
>>>>>> then
>>>>>> convert it to itkMesh using appropriate filters?
>>>>>> 
>>>>>> Any help will be appreciated,
>>>>>> 
>>>>>> Thanks
>>>>>> Rashed 
>>>>>> 
>>>>>> 
>>>>>> 
>>>>>> Luis Ibanez wrote:
>>>>>>> 
>>>>>>> Hi Tony,
>>>>>>> 
>>>>>>> 
>>>>>>> Well.... if you only have a point, then there is no normal to
>>>> compute.
>>>>>>> 
>>>>>>> You probably are thinking of a point from a surface, where a point
>>>>>>> belongs to several faces and have other points as neighbors.
>>>>>>> 
>>>>>>> 
>>>>>>> In that case you may want to look at the itk::SimplexMesh
>>>>>>> http://www.itk.org/Insight/Doxygen/html/classitk_1_1SimplexMesh.html
>>>>>>> 
>>>>>>> and its "ComputeNormal" method:
>>>>>>> 
>>>>>> 
>>>> http://www.itk.org/Insight/Doxygen/html/classitk_1_1SimplexMesh.html#itk_1_1
>>>>>> SimplexMesha5
>>>>>>> 
>>>>>>> 
>>>>>>>     Regards,
>>>>>>> 
>>>>>>> 
>>>>>>>        Luis
>>>>>>> 
>>>>>>> 
>>>>>>> -------------------
>>>>>>> tony hakki wrote:
>>>>>>>> Is it possible to calculate normal of a point in ITK? If yes, Could
>>>>>> you 
>>>>>>>> tell which class should be used?
>>>>>>>> thank you
>>>>>>>>  
>>>>>>>> 
>>>>>>> _______________________________________________
>>>>>>> Insight-users mailing list
>>>>>>> Insight-users at itk.org
>>>>>>> http://www.itk.org/mailman/listinfo/insight-users
>>>>>>> 
>>>>>>> 
>>>>>> 
>>>>> 
>>>>> _______________________________________________
>>>>> Insight-users mailing list
>>>>> Insight-users at itk.org
>>>>> http://www.itk.org/mailman/listinfo/insight-users
>>>>> 
>>>>> 
>>>> 
>>> 
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>>> 
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> 
> 
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