[Insight-users] PolylineParametricPath

[Thomas Boettger]

Hi Luis,

I simply wanted to iterate over the all indices and call Evaluate(). The 
loop shouldn't crash if there is no point in the path, but it does when 
I use EndOfInput() of cause.

I read the documentation and saw the class was suggested for contour 
representation. So I play around and don't see the benefit of this 
datastructure. I am not interested in some image values following the 
path, maybe in future. For now I simply want to traverse the path, to 
get the values and then draw it into a widget. One could use a point 
list. Furthermore there is no direct bounding box computation. And I am 
not sure how to access the vertex list. Do I have to use PathIterator 
and does a path only make sense together with an image?

Thanks,
Thomas

Luis Ibanez wrote:
> 
> Hi Thomas,
> 
> The method PolylineParametricPath::EndOfInput()
> is defined in the file
> 
>   Insight/Code/Commong/itkPolyLineParametricPath.txx
> 
> in lines 107-110 and it is simply returning
> 
>          m_VertexList->Size() - 1;
> 
> Unfortunately this value will be different from
> zero for a newly created path.
> 
> This method is used for avoiding to visit the
> first point twice in a closed path.
> 
> Given that the Vertex container m_VertexList is
> actually a VectorContainer that derives from the
> std::vector, we could redefine this method in
> terms of the std::vector    ::end()
> and use iterators in order to visit all the points.
> 
> 
> This is actually a bit confusing in the API, since
> EndOfInput() is not used as a vertex counter but
> rather as a discretized measure of the parameterization
> of the path.
> 
> Could you please describe the use that you were
> intending to make of this method ?
> 
> Is is likely that another method will actual
> provide the functionality that you need.
> 
> 
> Please let us know,
> 
> 
> Thanks
> 
> 
>   Luis
> 
> 
> ===================================================
> Thomas Boettger wrote:
> 
>> Hi all,
>>
>> I tried to use the class PolylineParametricPath.
>>
>> After instantiating a new PolylineParametricPath the EndOfInput() 
>> method returns a value different from zero. Is this correct? Because 
>> there is no point in the path and I thought the EndOfInput would 
>> return the same index as StartOfInput().
>>
>> Cheers,
>> Thomas
>>
>>
>>
> 
> 
> 
> 


-- 
Dipl.-Inform. Thomas Boettger
Deutsches Krebsforschungszentrum         (German Cancer Research Center)
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