<html><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; ">Hi Bryn,<div> in vmtk I keep the threshold fixed to -10 * collidingFrontsNegativeEpsilon, but if you come up with a smarter threshold, just let me know.</div><div>Keep in mind that colliding fronts was created to initialize level sets or deformable models. It's handy because it selectively initializes branches without side branches, but it may not be very accurate in catching the location of the boundary of the vessel (this very much depends on the image quality - if the signal in the vessel is high, it can do a pretty good job).</div><div><br></div><div>Last, you might be interested in knowing that if you add</div><div><br></div><div>fastMarchingFilter1->SetTargetReachedModeToOneTarget();</div><div><br></div><div>and</div><div><br></div><div>fastMarchingFilter2->SetTargetReachedModeToOneTarget();</div><div><br></div><div>in itkCollidingFrontsImageFilter.txx the filter will run sensibly faster.</div><div><br></div><div>It's in my todo list to add this as an extra option to the filter in ITK.</div><div><br></div><div>Best regards</div><div><br></div><div>Luca</div><div><br></div><div><br></div><div><br></div><div><br><div><div>On Feb 13, 2009, at 4:18 PM, Bryn Lloyd wrote:</div><br class="Apple-interchange-newline"><blockquote type="cite"><div>Hi Luca and Dan,<br><br><br>Is there any heuristic, which can help to choose a threshold on the output of the CollidingFrontsImageFilter?<br><br>I have following pipeline:<br><br>MRA image -> reader -> sigmoid -> colliding fronts -> threshold -> writer.<br><br>Unfortunately, the (subjective) optimal iso-level/threshold seems to vary quite a bit from case to case.<br><br><br>Thanks<br>Bryn<br><br></div></blockquote></div><br><div> <span class="Apple-style-span" style="border-collapse: separate; color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-align: auto; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0; "><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><span class="Apple-style-span" style="border-collapse: separate; color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; "><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><span class="Apple-style-span" style="border-collapse: separate; color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; "><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><div><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><div>--</div><div>Luca Antiga, PhD</div><div>Head, Medical Imaging Unit,<br>Biomedical Engineering Department,<br>Mario Negri Institute.<br>mail: Villa Camozzi, 24020, Ranica (BG), Italy<br>phone: +39 035 4535-381<br>email: <a href="mailto:antiga@marionegri.it">antiga@marionegri.it</a><br>web: <a href="http://villacamozzi.marionegri.it/~luca">http://villacamozzi.marionegri.it/~luca</a></div></div></div></div></div></div></span></div></span></div></span> </div><br></div></body></html>