<DIV>Hi Tony,</DIV> <DIV>I construct a phantom that is visible both in MRI images and optical images.This is used together with a biting fixation device to achieve a reproducible position relative to the Skull.It contain at least 3 points identifiable in MRI images(maximum 8 point),e.g.containing a lipid with characteristic MRI signal,as well as a structure easily recognized in the optical image,e.g a simple geometrical pattern in Black and White.</DIV> <DIV>I decide to let the user identify the required points for loading to iterativeclosestpoint2.CXX (combine with ItkRigid3DperspectiveTransform.h)input,but I don't know how can I gwt the coordinate of the required points.I read the tutorial on combining VTK+ITK(So I can display image) but I don't know what shall I add to the program to first ask the user to identify the points and then give me the coordinates on the selected points.</DIV> <DIV>Thanks for your help,</DIV> <DIV>Alireza<BR></DIV><p> 
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