It depends on the optimizer you are using. Optimizers that require the gradient, such as the GradientDescentOptimzier, FRPR etc will call GetValueAndDerivative.<br><br>The simplex optimizers, OnePlusOne, SPSA will invoke just GetValue.<br>
<br><br><div class="gmail_quote">On Thu, May 13, 2010 at 7:49 AM, pinpress <span dir="ltr"><<a href="mailto:sb_ji@yahoo.com">sb_ji@yahoo.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
<br>
Hi all,<br>
<br>
I am trying to modify the above class to implement a new image metric for<br>
image registration. There are two functions in the class:<br>
<br>
GetValue()<br>
<br>
and<br>
<br>
GetValueAndDerivative()<br>
<br>
When I connect the metric filter with other filters (e.g., interpolator,<br>
optimizer, transformer filters), and run the registration, I observed that<br>
it's always the function "GetValueAndDerivative()" is called, but not the<br>
"GetValue()". Since I am hoping to keep my implementation as simple as<br>
possible, I'd like to just modify the "GetValue()" function. So I wonder how<br>
I can force to use "GetValue()" function to return the similarity metric<br>
instead.<br>
<br>
I suspect it's just a flag or something like that to control, but I just<br>
wasn't able to figure out. Can someone help?<br>
--<br>
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