<div dir="ltr">Hi zhq,<div><br></div><div>This is explained in the ITK Software Guide</div><div><a href="http://www.itk.org/ItkSoftwareGuide.pdf">http://www.itk.org/ItkSoftwareGuide.pdf</a><br></div><div><br></div><div>in page 538.</div>
<div><br></div><div>The Value set in this function is a value in time.</div><div><br></div><div>More precisely, it is the time at which the front will start propagating from</div><div>that node point.</div><div><br></div>
<div>The context is that the output of the FastMarching filter is a time crossing map.</div><div><br></div><div>A map that tells you at what time, the front, reached every pixel.</div><div><br></div><div>The value that you set in node.SetValue() is the time at which you want to start</div>
<div>the front propagation from that pixel.</div><div><br></div><div>A typical use of this value is to be able to segment an image of a "Snowman"</div><div>where the bottom of the snowman is a large sphere, the thorax is a medium</div>
<div>sphere and the head is a small sphere.</div><div><br></div><div>You generate this shape by placing FastMarching nodes at the center of each </div><div>one of those spheres and then setting the time for the bottom to be earlier than </div>
<div>the time for the thorax, and leaving the time of the head for later.</div><div><br></div><div>In this way, the front at the bottom will have more time to propagate and to </div><div>fill up a larger region.</div><div>
<br></div><div>A bit of experimentation with at least two nodes, and different starting times</div><div>on each node will give you some familiarity with the effect of this parameter.</div><div><br></div><div> Hope this helps.</div>
<div><br></div><div> Luis</div><div><br></div></div><div class="gmail_extra"><br><br><div class="gmail_quote">On Sun, Dec 15, 2013 at 10:26 PM, zhq <span dir="ltr"><<a href="mailto:15891495523@126.com" target="_blank">15891495523@126.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div style="line-height:1.7;font-size:14px;font-family:arial">Hi ,Luis<div> I have another question about fast marching filter .</div>
<div> In the code , a sentence makes me confused . The sentence is node.SetValue( 0 ) . What dose the sentence means ? What role does the value play ?</div><div> Thanks !</div><div><div class="im">zhq <br><br>
<br><br><br><div></div><div></div><br>At 2013-12-13 21:57:26,"Luis Ibanez" <<a href="mailto:luis.ibanez@kitware.com" target="_blank">luis.ibanez@kitware.com</a>> wrote:<br> </div><div><div class="h5"><blockquote style="PADDING-LEFT:1ex;MARGIN:0px 0px 0px 0.8ex;BORDER-LEFT:#ccc 1px solid">
<div dir="ltr">Hi Zhq,<div><br></div><div>When running the FastMarching example, it is critical to do the following:</div><div><br></div><div><br></div><div>1) Place the seed points in the locations of the anatomy,</div><div>
that you want to segment.</div><div><br></div><div> Did you adjusted the location of the seed points to your image ?</div><div><br></div><div><br></div><div>2) Adjust the values of Alpha and Beta in the Sigmoid filter to the range</div>
<div> of intensities of the image produced by the Gradient magnitude filter.</div><div><br></div><div> Have you adjusted these values ?</div><div><br></div><div> It is useful to save the output image of the GradientMagnitude filter</div>
<div> and inspect it directly with an image viewer.</div><div><br></div><div> Instructions on this are available in the software guide.</div><div><br></div><div><br></div><div>3) Once you have inspected the gradient magnitude output, </div>
<div> proceed to adjust the Alpha and Beta in the sigmoid until you</div><div> get almost a black and white image as output.</div><div><br></div><div> For this, it also helps to save the image in a file and to inspect</div>
<div> it with an image viewer.</div><div><br></div><div>4) Finally, the "stoppingTime" parameter in the fastMarching filter</div><div> is also a critical parameter to define when the filter stops propagating</div>
<div> the front.</div><div><br></div><div><br></div><div>Please review these check points above, and if you continue having</div><div>difficulties, please post your input image in a public web site, so that</div><div>
we could inspect it and give it a try.</div><div><br></div><div><br></div><div> Thanks</div><div><br></div><div> Luis</div><div><br></div><div><br></div></div><div class="gmail_extra"><br><br><div class="gmail_quote">
On Thu, Dec 12, 2013 at 9:34 PM, zhq <span dir="ltr"><<a href="mailto:15891495523@126.com" target="_blank">15891495523@126.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div style="line-height:1.7;font-size:14px;font-family:arial">Dear all :<div> I run the code ,FastMarchingImageFilter.cxx , which included in InsightToolkit\Examples\Segmentation , a problem appears :</div><div> When the code runs to the sentence , fastMarching->Update() , </div>
<div> <img src="cid:1bab7104$1$142f970f544$Coremail$15891495523$126.com" style="line-height:1.7"></div><div> <span style="color:rgb(67,67,67);font-family:Arial,sans-serif;line-height:24px">This process occupies 25% of the CPU, and the code stop in this sentence .</span></div>
<div><span style="color:rgb(67,67,67);font-family:Arial,sans-serif;line-height:24px"> What the problem could be ?</span></div><div><span style="color:rgb(67,67,67);font-family:Arial,sans-serif;line-height:24px"> Thanks in advance !</span></div>
<div><span style="color:rgb(67,67,67);font-family:Arial,sans-serif;line-height:24px">zhq</span></div></div><br><br><span title="neteasefooter"><span><div><div style="border-top:#cccccc 1px solid;padding:10px 5px;font-size:12px;color:#666;line-height:22px">
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