[Insight-users] Levelsets-v4 curvature term drives circles to squares (2-D) (+other issues)

[Arnaud Gelas]

Hi Vaaksiainen,

As Bill mentioned, to get the best performance make sure to build your 
program in Release. It can make a huge difference.

Now speaking about the performance of the v4 framework, it is not 
multi-threaded for all level set representations as it was for the 
previous implementation; and some there is still some work to be done on 
that matter. Also for some of the sparse cases, there are still some 
optimizations to be made in the code.

I will try to look at some of these issues during the holidays...

---

Meanwhile, could you make a minimal example with one image to reproduce 
this behavior, please?

Thanks,
Arnaud


On 12/17/2012 04:45 PM, Bill Lorensen wrote:
> Make sure you build your program Release and not Debug.
>
> On Mon, Dec 17, 2012 at 10:02 AM, Vaaksiainen <vaaksiainen at gmail.com> wrote:
>> Update to this question and some credit to authors :) now that I've
>> tried it, Chan-Vese levelset works nicely, and although a single
>> iteration is slowish, the convergence is very fast from the initial
>> circle initialization (~comparable with v3 snake in total time). I
>> remark, that default value of Heaviside epsilon is kinda high, so
>> changing that was my first solution. The original question with plain
>> curvature or geodesic active contour remains open still.
>>
>> I try not to profile spammer, so I also attach here my thanks to
>> Arnaud regarding my previous question
>> (LevelSetEquationTermContainer->SetInput() ? ).
>>
>> Best,
>>
>> -Vaaksiainen
>>
>> 2012/12/17 Vaaksiainen <vaaksiainen at gmail.com>:
>>> Hi,
>>>
>>> I'm learning Levelsets-v4 hard. Currently, after not getting the
>>> convergence appreciated, I tried the following:
>>>
>>> I set up LevelSetEvolution following the
>>> itkSingleLevelSetDenseImage2DTest -example, but I use only propagation
>>> or curvature terms one at a time. I set the feature images unitary,
>>> and initialize the levelset as small circles (equi-spaced).
>>>
>>> Problem: curvature term drives circles towards squares (really
>>> sharp-edged NxN pixel squares eventually), while obviously should not.
>>> Somewhat similar happens with the propagation term alone, where I find
>>> speed along coordinate axes to be dominative.
>>>
>>> What I might be doing wrong here?
>>>
>>> Another question, is it possible to obtain (approximately) similar
>>> behaviour using GeodesicActiveContourLevelSetImageFilter and
>>> Levelsets-v4 framework with propagation, curvature and advection
>>> terms. I tried, but obvious reasons (mentioned above) already
>>> cancelled this study. Also: number of iterations per time unit seems
>>> to be drastically lower (hundred folds) with the new framework.
>>>
>>> -V
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