<html><body><div style="color:#000; background-color:#fff; font-family:times new roman, new york, times, serif;font-size:12pt"><div id="yiv1540406547"><div><div style="color: rgb(0, 0, 0); background-color: rgb(255, 255, 255); font-size: 12pt; font-family: 'times new roman', 'new york', times, serif; "><div id="yiv1540406547yui_3_2_0_16_131908874370148">Thanks Vivien!</div><div id="yiv1540406547yui_3_2_0_16_131908874370148">That's right, the 'deformation' in this case is actually the translation of the lower ball, and I think that both algorithms caught this since the there is no much vectors around the upper ball. </div><div id="yiv1540406547yui_3_2_0_16_131908874370148">I actually also tried Demons and BSpline with another phantom, and the motion is closer to a local deformation,</div><div id="yiv1540406547yui_3_2_0_16_131908874370148"><span class="Apple-style-span" style="font-family: monospace; white-space: pre; "><i>Demons:</i></span></div><div
id="yiv1540406547yui_3_2_0_16_131908874370148"><span class="Apple-style-span" style="font-family: monospace; white-space: pre; "><i>http://dl.dropbox.com/u/1906263/squash_demons.gif</i></span></div><div id="yiv1540406547yui_3_2_0_16_131908874370148"><span class="Apple-style-span" style="font-family: monospace; white-space: pre; "><i>B-Spline:</i></span></div><div id="yiv1540406547yui_3_2_0_16_131908874370148"><span class="Apple-style-span" style="font-family: monospace; white-space: pre; "><i>http://dl.dropbox.com/u/1906263/squash_bspline.gif</i></span></div><div id="yiv1540406547yui_3_2_0_16_131908874370148"><br></div><div id="yiv1540406547yui_3_2_0_16_131908874370148">While when I look at them now, I start to feel that maybe BSpline got the motion right, will try to assess the accuracy.</div><div id="yiv1540406547yui_3_2_0_16_131908874370148">For Demons, it's not completely unacceptable for the single ball (<span class="Apple-style-span"
style="font-family: monospace; white-space: pre; "><i>http://dl.dropbox.com/u/1906263/squash_demons.gif</i></span>); but for the translation motion, it just couldn't work it out (<span class="Apple-style-span" style="font-family: monospace; white-space: pre; "><i>http://dl.dropbox.com/u/1906263/golf_demons.gif</i></span>). Is it because of the nature of Demons that prevents it from working for translation?</div><div id="yiv1540406547yui_3_2_0_16_131908874370148"><br></div><div id="yiv1540406547yui_3_2_0_16_131908874370148">Thanks a lot for your help!</div><div style="font-size: 12pt; font-family: 'times new roman', 'new york', times, serif; " id="yiv1540406547yui_3_2_0_16_131908874370154" class="yiv1540406547yui_3_2_0_16_131908874370152"><div style="font-size: 12pt; font-family: 'times new roman', 'new york', times, serif; " class="yiv1540406547yui_3_2_0_16_131908874370157" id="yiv1540406547yui_3_2_0_16_131908874370180">
<div id="yiv1540406547"><span class="yiv1540406547Apple-style-span" style="background-color: rgb(255, 255, 255); font-size: 16px; "><pre>On 10/16/2011 07:36 PM, Ryan Guan wrote:
><i> Dear ITK Users,
</i>
Hi Ryan,
><i> I am new to DIR world and I need to work out the best DVFs for my
</i>><i> 'deformed' phantom images.
</i>><i> I tried Demons and B-Spline as in DeformableRegistration2 and
</i>><i> DeformableRegistration7, but neither of them seem to be very good. The
</i>><i> results can be downloaded from my dropbox:
</i>><i> Demons:
</i>><i> http://dl.dropbox.com/u/1906263/golf_demons.gif
</i>><i> B-Spline:
</i>><i> http://dl.dropbox.com/u/1906263/golf_bspline.gif
</i>><i>
</i>><i> The B-Spline ones look more reasonable but still with quite obvious
</i>><i> errors at the region where there is no deformation. I guess there might
</i>><i> be something to do before deformable registration could be helpful or
</i>><i> there might be better algorithms for this case? Your suggestions will be
</i>><i> appreciated VERY MUCH!
</i>
In your image you have a background which is not moving. It is in
contradiction with the image registration that tries to find a smooth
vector field on the whole image. In your case your transformation is
locally a translation so you should try to find a translation on a
masked image that isolate your object from your background.
><i> Another question regarding visualizing vector fields in Paraview: it
</i>><i> seems that Paraview display PNG (images) and VTK (vector field, after
</i>><i> 'scalars_X*iHat+scalars_Y*jHat' and glyph) in different Y orientations.
</i>><i> I haven't figured out how to correctly overlay them, but just tried to
</i>><i> flip and shift the vector field in Paraview, so the vector field in the
</i>><i> above results might not be quite aligned with the images. Will also
</i>><i> appreciate if you can help to let me know the best&correct way to
</i>><i> visualize the vector fields!
</i>
I don't know how Paraview work but for vertor field visualisation I use
VV (http://www.creatis.insa-lyon.fr/rio/vv)
><i> Thanks a lot for any inputs!
</i>><i>
</i>><i> Ryan
</i>
--
Vivien Delmon
PhD student at CREATIS, Lyon
Supported by ANRT and ELEKTA
http://www.creatis.insa-lyon.fr/rio</pre></span>
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