[Rtk-users] question about rtkDraw*ImageFilter

[Mathieu Dupont]

Hello Simon, 

I started to implement what I suggested : 

https://github.com/wrzof/RTK/blob/rewrite_DrawImageFilter/code/rtkDrawImageFilter.h
and 
https://github.com/wrzof/RTK/blob/rewrite_DrawImageFilter/code/rtkDrawCylinderImageFilter.h

rtk::DrawCylinderImageFilter derives from rtk::DrawImageFilter and specializes 
it (by defaulting the template parameter TSpatialObject with 
DrawCylinderSpatialObject). 

By default, DrawCylinderImageFilter uses Add2 for filling output image (to be 
backward compatible (all tests pass)). I created Discard (I did not find 
equivalent in itk) functor in order to do what I wanted in my first email.  

I just implemented DrawCylinderImageFilter, the others will follow. 

What do you think about it ?

Le vendredi 30 octobre 2015, 11:56:50 Mathieu Dupont a écrit :
> Hi,
> 
> In case of your first solution, you can not chain several
> Draw*ImageFilters. For example, if you want to create small cylinders in
> a big cylinder.
> 
> Your second solution is better.
> 
> One another solution can be a thing like itk:SpatialObject but more
> simpler. An rtk::SpatialObject which one function (isInside(point)). We
> create a rtkDrawImageFilter class and implement ThreadedGenerateData
> like this :
> 
> DrawImageFilter<InImage, OutImage, rtkSpatialObject,
> rtkFillFunctor>::ThreadedGenerateData(const OutputImageRegionType&
> outputRegionForThread,                 ThreadIdType itkNotUsed(threadId)
> {
> ...
> 
>   while( !itOut.IsAtEnd() )
>      {
>      this->GetInput()->TransformIndexToPhysicalPoint(itOut.GetIndex(),
> point);
> 
>     if(m_rtkSpatialObject.isInside(point)
>       itOut.Set(m_rtkFillFunctor(density, itIn.Get());
> ...
> }
> 
> 
> DrawConeImageFilter class can be a child of this new DrawImageFilter
> (with new methods like setAngle, SetRadius which will adjust the
> rtkConeSpatialObject)
> 
> This solution suppress duplicated code in
> Draw*ImageFilter::ThreadedGenerateData and makes easier implementation
> of another type of filling.
> 
> On 28/10/2015 20:52, Simon Rit wrote:
> > Hi Mathieu,
> > Thanks for pointing this out. I agree that it might not be the best
> > solution, yet one could argue that you could simply create a constant
> > image with 0 to do what you'd like from the current implementation. My
> > main problem is that I just tried to do what you suggest and some tests
> > then fail... which shows the obvious, it's not a backward compatible
> > change. I see two solutions:
> > - keep it as is and you use ConstantImageFilter + we remove useless add
> > filters,
> > - a more complex but maybe more elegant solution: add a third template
> > parameter for the operation that would allow the user to do what he'd
> > like in a functor. That's what's done with filters that derive from
> > itk::UnaryImageFilter
> > <http://www.itk.org/Doxygen/html/classitk_1_1UnaryFunctorImageFilter.html>
> > .
> > The default would be itk::Add2 but we could find or implement another
> > one that simply discards the pixel value.
> > What do you think?
> > Simon
> > 
> > PS: looking in the code, I just found that rtk::DrawConeImageFilter is
> > not consistent with the others, it was always setting to 0 outside...
> > that's been fixed!
> > 
> > On Wed, Oct 28, 2015 at 4:47 PM, Mathieu Dupont <mdupont at cppm.in2p3.fr
> > 
> > <mailto:mdupont at cppm.in2p3.fr>> wrote:
> >     Hello everyone,
> >     
> >     I have a question/suggestion about the set of rtkDraw*ImageFilter.
> >     This filter are written as additive filters: for example, in
> >     rtkDrawEllipsoidImageFilter.txx, we can find
> >     
> >     for(..)
> >     
> >       itOut.Set( ellipsoid.density + itIn.Get() )
> >     
> >     instead of
> >     
> >     for(..)
> >     itOut.Set( ellipsoid.density )
> >     
> >     
> >     I think it can be more flexible the second option, because we can
> >     always associate Draw*ImageFilter and itkAddImageFilter to get an
> >     additive filter.
> >     
> >     Moreover, the  rtkDrawGeometricPhantomImageFilter class already uses
> >     itkAddImageFilter in order to have additive filters (which is
> >     redundant in current situation).
> >     
> >     What do you think ?
> >     
> >     
> >     
> >     
> >     
> >     Regards
> >     
> >     
> >     
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