[Insight-developers] Comments please: Prototype DTI fiber tracking in ITK

[Torsten Rohlfing]

Hi Karthik --

Thanks for your feedback.

Karthik Krishnan wrote:

>>
>> The tracking filter inherits from itk::SpatialObjectSource (also 
>> included in aforementioned archive) and generates an 
>> itk::GroupSpatialObject as its output. The group object contains all 
>> fibers as its children, where each fiber is represented by an 
>> itk::DTITubeSpatialObject object.
>>
> I like the idea of having a SpatialObjectSource. For consistency, I 
> think the SpaitialObjectReader should also derive from this. With the 
> current layout, of the class hierarchy, it doesn't really fit in that 
> well. Julien will have more to say on that.

To tell you the truth, I was quite surprised that there was no 
SpatialObjectSource already.

>> I also include a first, simple test in itkFiberTrackingTest.cxx, 
>> which basically constructs a 5x5x5 tensor volume with a single 
>> straight "fiber" in z-direction in the center of the volume. Note 
>> that since the tensors are all exactly vertical, you'll basically get 
>> five identical fibers as output. I am not saying it's particularly 
>> creative test case.
>
>
> If you are ok with it, we could commit this to ITK.

Fundamentally, I am okay with it. However, I am not entirely happy with 
the iterator design yet. At the very least I would like create a traits 
class for the code that takes a tensor and computes the next line 
segment direction. This way, we could easily plug different such 
algorithms into the fiber iterator. For example, a Monte Carlo-type 
tracking would then simply be realized by pluging in a different such 
traits class.

This is a matter of a few hours of thinking and re-arranging things on 
my part, so if you don't mind, I'd suggest you give me another day and 
then I'll post an updated version that is more elegantly designed.

-- 
Torsten Rohlfing, PhD          SRI International, Neuroscience Program
 Research Scientist             333 Ravenswood Ave, Menlo Park, CA 94025
  Phone: ++1 (650) 859-3379      Fax: ++1 (650) 859-2743
   torsten at synapse.sri.com        http://www.stanford.edu/~rohlfing/

     "Though this be madness, yet there is a method in't"