[Insight-users] fast marching algorithm very time consuming?

[Michal Plotkowiak]

In message <46C06E15.7050200 at kitware.com> Luis Ibanez <luis.ibanez at kitware.com> 
writes:
> 

as far as I see, the fact that I increased the treshold value allowed me to 
store the result in the final output. Previously I was reading results from the 
intermediate output 4. But still to get a complite segmentation i need to set 
my values to around 2000 (this value is also suggested by my output map). 
Again, it takes very long to get any results.

michal

> Hi Michael,
> 
> FastMarching should take only seconds in that size of data set.
> 
> You are requesting a stopping time of 2000 and thresholding at 100,
> that means that all the times from 101 to 2000 are going to waste.
> 
> If you are going to threshold at 100, you can just set the stopping
> time to a value slightly above the threshold. For example, you could
> stop at 110.
> 
> The heuristic for choosing the stopping time relates to the size of
> the object that you want to segment and to the average value of the
> speed image in the region that goes from the seed points to the
> boundaries of the object that you want to segment.
> 
> 
> 
> BTW: What is the profile of your computer ?
>       OS, Processor, Memory ?
> 
> 
> 
>     Regards,
> 
> 
>        Luis
> 
> 
> 
> -------------------------
> Michal Plotkowiak wrote:
> > Hi,
> > 
> > I'm segmenting 3D data of a heart using FastMarchingImageFilter program. 
The 
> > data size is 256x256x362. Every 5th slice I generate seed points 
(approximately 
> > 300 on a slice). My threshold time is 100 and stoping time 2000. When I ran 
the 
> > simulation only for 6 slices I get good results but after about an hour. 
When I 
> > tried to run the sumulation for all the slices (362) two days wasn't 
enough...
> > 
> > Has anyone some experience with FastMarching algorithm? The time needed for 
the 
> > simulation seems to be far too long. Should I somehow change my approach to 
the 
> > problem?
> > 
> > many thanks
> > michal
> > 
> > 
> 

-- 
Michal Plotkowiak
Doctoral Researcher
Oxford University LSI DTC