<div dir="ltr">On an even simpler note ... I have two black and white boundary images, the second of which is simply translated by (30, 15) pixels. Using the Translation Transform (ImageRegistration1 example) I would expect to get a very close match. Instead the images are still misaligned quite a bit. The results show a translation of (-2, -5) which I believe is in spatial measurements correct? My images have unit spacing so I would have expected (30, 15) no? <div>
<br></div><div>Again, any help is appreciated.</div><div>Maureen<br><br><div class="gmail_quote">On Fri, Jul 25, 2008 at 12:37 PM, Maureen Haining <<a href="mailto:mfhaining@gmail.com">mfhaining@gmail.com</a>> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;"><div dir="ltr">Hello Users,<div><br></div><div>I have two images that are essentially aligned that I am using to experiment with the Similarity Transform with Regular Step Gradient Descent Optimizer (I am using example 7). The fixed image is a traced black and white boundary image of moving image. I am having trouble understanding the results.</div>
<div><br></div><div><p style="margin:0.0px 0.0px 0.0px 0.0px;font:11.0px Monaco">Result = </p>
<p style="margin:0.0px 0.0px 0.0px 0.0px;font:11.0px Monaco"> Scale = 4.15432</p>
<p style="margin:0.0px 0.0px 0.0px 0.0px;font:11.0px Monaco"> Angle (radians) 0.00397598</p>
<p style="margin:0.0px 0.0px 0.0px 0.0px;font:11.0px Monaco"> Angle (degrees) 0.227807</p>
<p style="margin:0.0px 0.0px 0.0px 0.0px;font:11.0px Monaco"> Center X = 374.818</p>
<p style="margin:0.0px 0.0px 0.0px 0.0px;font:11.0px Monaco"> Center Y = 361.912</p>
<p style="margin:0.0px 0.0px 0.0px 0.0px;font:11.0px Monaco"> Translation X = -0.171362</p>
<p style="margin:0.0px 0.0px 0.0px 0.0px;font:11.0px Monaco"> Translation Y = -0.684359</p>
<p style="margin:0.0px 0.0px 0.0px 0.0px;font:11.0px Monaco"> Iterations = 500</p>
<p style="margin:0.0px 0.0px 0.0px 0.0px;font:11.0px Monaco"> Metric value = 1337.12</p><p style="margin:0.0px 0.0px 0.0px 0.0px;font:11.0px Monaco"><br></p><p style="margin:0.0px 0.0px 0.0px 0.0px;font:11.0px Monaco">
I am surprised to see a scaling factor introduced. I have set the optimizerScales to 1 (scale) and 1 (angle). And indeed the moving image is scaled down by about a factor of 4. Can anyone shed any light on this for me? </p>
<p style="margin:0.0px 0.0px 0.0px 0.0px;font:11.0px Monaco"><br></p><p style="margin:0.0px 0.0px 0.0px 0.0px;font:11.0px Monaco">Also, can anyone recommend a good reference book that is an introduction to registration techniques and would explain from an application viewpoint the pros and cons of particular transformations. I have Terry Yoo's book but I would like something more introductory. I have also read the itk software guide but would like to find another reference. </p>
<p style="margin:0.0px 0.0px 0.0px 0.0px;font:11.0px Monaco"><br></p><p style="margin:0.0px 0.0px 0.0px 0.0px;font:11.0px Monaco">Thanks for any help you can give. </p><p style="margin:0.0px 0.0px 0.0px 0.0px;font:11.0px Monaco">
Maureen</p></div></div>
</blockquote></div><br></div></div>