[Insight-users] ImagePCAShapeModelEstimator

[Zachary Pincus]

> Please read the ITK Software Guide
>
>    http://www.itk.org/ItkSoftwareGuide.pdf
>
> in particular section 9.3.7, in pdf-page 587 where you
> will find explained in detail how to use the class:
>
>         itk::ImagePCAShapeModelEstimator


Actually, the documentation is not particularly detailed on how to  
use the ImagePCAShapeModelEstimator class -- to my mind, this has  
been a fairly long-standing bugaboo in the software guide. It merely  
states that the ImagePCAShapeModelEstimator class can be used to  
generate a shape model. The example then proceeds to read in a pre- 
computed model from the command line and nowhere illustrates how to  
compute such a model.

Nor is the doxygen particularly informative as to the precise nature  
of the inputs to and outputs from the shape model estimator. I'd be  
happy to write a paragraph for the guide, and/or fix the doxygen if  
anyone wants. (I also think that the computation of the shape model  
may be sped up significantly in some cases by use of the SVD instead  
of an eigen-decomposition. I'm exploring this possibility too...)

For reference, you need to pass the ImagePCAShapeModelEstimator a set  
of signed distance function images. So if you have a set of black-and- 
white "mask" images representing a population of shapes, you need to  
convert those to signed distance maps with either the  
ApproximateSignedDistanceMapImageFilter class or the  
SignedDanielssonDistanceMapImageFilter class. Then feed these signed  
distance maps as the inputs to the ImagePCAShapeModelEstimator class.

Zach Pincus

Program in Biomedical Informatics and Department of Biochemistry
Stanford University School of Medicine


On Sep 8, 2005, at 4:28 PM, Luis Ibanez wrote:

>
> Hi Quan,
>
> Please read the ITK Software Guide
>
>    http://www.itk.org/ItkSoftwareGuide.pdf
>
> in particular section 9.3.7, in pdf-page 587 where you
> will find explained in detail how to use the class:
>
>         itk::ImagePCAShapeModelEstimator
>
>
> The source code of the associated example can be found at
>
>
>     Insight/Examples/Segmentation/
> GeodesicActiveContourShapePriorLevelSetImageFilter.cxx
>
>
>
>
>    Regards,
>
>
>       Luis
>
>
>
>
> ----------------
> Quan Chen wrote:
>
>> Just want to confirm my understanding.  The input (training image)  
>> to the ImagePCAShapeModelEstimator should be the level set image,  
>> right?  So if we have contours, we should create levelset image by  
>> ourselve with the zero set the contour itself before feeding to  
>> the PCA estimator.  
>> --------------------------------------------------------------------- 
>> ---
>> _______________________________________________
>> 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
>