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<font face="Helvetica, Arial, sans-serif"><small>Hi Vijay,<br>
<br>
The result of the <font face="Courier New, Courier, monospace">FastMarchingImageFilter<font
face="Helvetica, Arial, sans-serif"> </font></font>is heavily
dependent on the speed image (which is provided as the filter input):
if the speed image does not contain the features you require, the
results will not be meaningful. Further, because the contour is
controlled by position only (ie. the front expands outwards according
to the speed image values - not curvature or advection), you must
ensure that the important edges of your speed image are close to 1.0 to
ensure the front does not 'leak' into unwanted regions too early.<br>
<br>
I highly recommend that you read the section on Fast Marching
segmentation in the Insight Software Guide (
<a class="moz-txt-link-freetext"
href="http://www.itk.org/ItkSoftwareGuide.pdf">http://www.itk.org/ItkSoftwareGuide.pdf</a>
, around section 9.3.1) and
also (if you can lay your hands on it) the book by Sethian mentioned in
the <font face="Courier New, Courier, monospace">Algorithms/itkFastMarchingImageFilter.h</font>
header file/documentation. After doing this reading, it is probably
worthwhile to comment out most of your Fast Marching code (leaving only
the speed image computation part) and write out the speed image to disk
to ensure it captures the edges/features you are interested in. Also,
be mindful of your image viewer when viewing the output of the Fast
Marching method. In most image viewers, the output will typically look
binary (black and white only) because the parts of the image the front
did not reach will be assigned a large value (in the order of
3.402823e38) whereas the parts the front did reach will be assigned the
time-crossing value (eg. 0-1000) -- 1000 compared to </small></font><font
face="Helvetica, Arial, sans-serif"><small>3.402823e38 is very small
and will appear black. You may want to threshold the output between [0
.. StoppingValue] to strip away these very large portions of the output.</small></font><br>
<font face="Helvetica, Arial, sans-serif"><small><br>
In regards to supplying your image to the ITK community: it is probably
best to upload the image to some web-based file share system and paste
the link into an email to the insight-users list.<br>
<br>
HTH<br>
<br>
Cheers, Dan</small></font><br>
<br>
<small><font face="Helvetica, Arial, sans-serif">vijay kumar wrote:</font></small>
<blockquote cite="mid170416.62136.qm@web57906.mail.re3.yahoo.com"
type="cite">
<div><small><font face="Helvetica, Arial, sans-serif">Hi,</font></small></div>
<div><small><font face="Helvetica, Arial, sans-serif">I modified
FastMarchingImageFilter.cxx that is found in Examples\Segmentation to
work on a 3D analyze format image. After compilation, I executed it
from the command line:</font></small></div>
<div><small><font face="Helvetica, Arial, sans-serif"> </font></small></div>
<font size="2">
<div><font face="Helvetica, Arial, sans-serif">FM_Filter3D.exe
mri4itk.hdr mri4itkResult.hdr </font></div>
<font face="Helvetica, Arial, sans-serif" size="2"> </font>
<div><font face="Helvetica, Arial, sans-serif" size="2">1.25 -8.0
75.0 10 15 </font></div>
<font face="Helvetica, Arial, sans-serif" size="2"> </font>
<div><font face="Helvetica, Arial, sans-serif" size="2">108 125 1 110
125 5 112 124 10 113 124 15 113 123 20 107 130 25 94 136 32</font></div>
<font face="Helvetica, Arial, sans-serif" size="2"> </font>
<div><font face="Helvetica, Arial, sans-serif" size="2"> </font></div>
<font face="Helvetica, Arial, sans-serif" size="2"> </font>
<div><font face="Helvetica, Arial, sans-serif" size="2">The second
line has values for sigma, alpha, beta, threshold and stopping time</font></div>
<font face="Helvetica, Arial, sans-serif" size="2"> </font>
<div><font face="Helvetica, Arial, sans-serif" size="2">The third
line contains indices (x,y,z) for a set of 7 points. All three lines
were concatenated into one when running the program. The segmentation
results don't look good. The binary image contains a large white spot
in each slice. I am trying to segment the right artery which appears as
a white spot on the right side in the input image. The text of my
program is given below. I tried to attach the image (mri4itk.hdr,
mri4itk.img) to this email, but the email bounced. The size is
approximately 3 MB. Can I send the images somehow? </font></div>
<font face="Helvetica, Arial, sans-serif" size="2"> </font>
<div><font face="Helvetica, Arial, sans-serif" size="2"> </font></div>
<font face="Helvetica, Arial, sans-serif" size="2"> </font>
<div><font face="Helvetica, Arial, sans-serif" size="2">Thanks,</font></div>
<font face="Helvetica, Arial, sans-serif" size="2"> </font>
<div><font face="Helvetica, Arial, sans-serif" size="2">Vijay</font></div>
</font></blockquote>
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