[Insight-users] Radius of Gaussian?

[Neuner Markus]

Sorry for this bad sentence i accidently pressed send.

A radius with 512 does not make sense because a z-score of 1 includes 
all values within +/-  the Standarddeviation.


Neuner Markus wrote:
>
> Since your maximum is 1 and your radius is 512 this does not make 
> sense because all z-scores all smaller than 1 and inside the spatial 
> object.
>
> motes motes wrote:
>> How should the radius of the gaussian be understood? I have done this:
>>
>>     const unsigned int gaussianDim = 1;
>>     typedef itk::GaussianSpatialObject<gaussianDim>        GaussianType;
>>     typedef itk::Point<double, gaussianDim>                
>> GaussianPoint;
>>
>>     const static int gaussian_radius = 512;
>>     const static int gaussian_max = 1;
>>     GaussianType::Pointer m_Gaussian = GaussianType::New();
>>     m_Gaussian->SetMaximum(1);
>>     m_Gaussian->SetRadius(512);
>>
>>     GaussianPoint pos;
>>     for (int i=0; i<100; i++) {
>>       pos[0] = -300 + i*5;
>>
>>       double weight = 0.0;
>>       m_Gaussian->ValueAt(pos, weight);
>>       std::cout << "pos = " << pos << std::endl;
>>       std::cout << "weight = " << weight << std::endl;
>>     }
>>
>> But I only get non-zero values in the range [-35, 35]:
>>
>> pos = [-35]
>> weight = 9.87711e-267
>> pos = [-30]
>> weight = 3.69388e-196
>> pos = [-25]
>> weight = 1.91856e-136
>> pos = [-20]
>> weight = 1.3839e-087
>> pos = [-15]
>> weight = 1.38634e-049
>> pos = [-10]
>> weight = 1.92875e-022
>> pos = [-5]
>> weight = 3.72665e-006
>> pos = [0]
>> weight = 1
>> pos = [5]
>> weight = 3.72665e-006
>> pos = [10]
>> weight = 1.92875e-022
>> pos = [15]
>> weight = 1.38634e-049
>> pos = [20]
>> weight = 1.3839e-087
>> pos = [25]
>> weight = 1.91856e-136
>> pos = [30]
>> weight = 3.69388e-196
>> pos = [35]
>> weight = 9.87711e-267
>> pos = [40]
>>
>>
>> When the radius is 512 I thought that the bell curve would have
>> support in the interval: [-512, 512] but it seems that the radius in
>> the gaussian expresses something else.
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