<html><body><div style="color:#000; background-color:#fff; font-family:times new roman, new york, times, serif;font-size:12pt"><div><span>Hi Dan,</span></div><div><span><br></span></div><div><span>In order to provide you more information I did a small modification to the SpeedFunctionToPathFilter. I have added an image writer so that I can save what you call the current arrival function. At the same time, I compare the result with a well-known toolbox in matlab that performs the fast marching (btw, this is my final purpose; using itk instead of matlab). What I found is that the arrival functions differ significantly (might the problem be on the Fastmarching itself?). Moreover, I do obtain a path in matlab, no matter the end point.</span></div><div><br><span></span></div><div><span>To illustrate you the situation I provide you screenshots of the matlab results (example_D_one_.jpg and example_path_one.jpg files) and the arrival function with itk
(example_D_two.jpg), since no path is obtained. For this example, I have used an image of mine. I was using your Synthetic-04-Speed to evaluate the filter, but I can't not read zraw in matlab, so that is why I send you this other example. However, I will try to solve the zraw problem so that I can run </span><span>the matlab code in Synthetic-04-Speed.</span></div><div><span><br></span></div><div><span>Regarding your saying about the path, perhaps on an image as </span><span>Synthetic-04-Speed there should be no path when a point is badly placed (due to the completely dark background) but, in the image as the one I am using I think it should get something (as in matlab). I am not an expert but I believe that one of the advantage/disadvantage of minimal paths approaches is the fact that it will always find a path given two points. But, as I said before, according to the results I am sending you, I believe the problem seems to come from the arrival
function and not from the path search. What do you think?</span></div><div><br><span></span></div><div> Since my firewall does not allow me to attach files to emails, you can obtain the screenshots here: http://www.creatis.insa-lyon.fr/~zuluaga/fm_issues/<br><span></span></div><div><span>regards,</span></div><div><br><span></span></div><div><span>Maria</span></div><div><br><span></span></div><div><span>ps. If you want I can also send you the image of my examples, while I solve the zraw problem. It is very small (184x184x23). I could place it on my server.<br></span></div><div> let me know if that sounds ok.<br><span></span></div><div><span><br></span></div><div><br><span></span></div><div><span><br></span></div><div><br></div><div><br><span></span></div><div><span></span></div><div><br></div><div style="font-family: times new roman, new york, times, serif; font-size: 12pt;"><div style="font-family: times new roman, new york, times, serif;
font-size: 12pt;"><font size="2" face="Arial"><hr size="1"><b><span style="font-weight:bold;">De:</span></b> Dan Mueller <dan.muel@gmail.com><br><b><span style="font-weight: bold;">Para:</span></b> Maria Alejandra Zuluaga Valencia <mariazulv@yahoo.es><br><b><span style="font-weight: bold;">CC:</span></b> "insight-users@itk.org" <insight-users@itk.org><br><b><span style="font-weight: bold;">Enviado:</span></b> miércoles 6 de julio de 2011 14:43<br><b><span style="font-weight: bold;">Asunto:</span></b> Re: [Insight-users] Problem with Fast marching minimal path extraction<br></font><br>Hi Maria,<br><br>Can you please provide some more information?<br><br>Which synthetic image are you using? Where are you placing the seed point?<br><br>I would not expect that every seed point will work -- the seed point<br>needs to be in a region which is reachable by the Fast Marching<br>expanding front. For example, placing the seed point in a region
with<br>low speed (near 0.0) will not work.<br><br>Attached are a few examples using different seed points.<br><br>Regards, Dan<br><br>On 5 July 2011 17:23, Maria Alejandra Zuluaga Valencia<br><<a ymailto="mailto:mariazulv@yahoo.es" href="mailto:mariazulv@yahoo.es">mariazulv@yahoo.es</a>> wrote:<br>> Hi,<br>> I am trying to use the minimal path extraction algorithm reported in:<br>> <a href="http://hdl.handle.net/1926/1332" target="_blank">http://hdl.handle.net/1926/1332</a><br>> After some minor compilation errors I managed to make it work. However, I<br>> found the behavior is a bit weird. As an example:<br>> if I test with one of the Synthetic images provided and the path points<br>> given, everything works fine. But, as soon as I change one of the path end<br>> points it stops working. By stop working I mean that the extracted path<br>> contains no points. I've tried with several examples and it is always the<br>>
case.<br>><br>> As far as I know, no matter how bad I place my end point, I should get a<br>> minimal path connecting the end and start points. Has any one had the same<br>> kind of problem? did you managed to fix it?<br>> thanks,<br>> Maria<br><br><br></div></div></div></body></html>