how do i compensate for photographic viewpoint and distortion hi to all out there we have this problem and i m not certain i m solving it in the correct way i was wondering if anyone can shed light on this or point me in the right place to look we have an x ray imaging camera and a metallic tube with a cylindrical hole passing through it at a right angle to the tube s axis image x ray source screen metallic tube we know source screen centre distance radius of the tube radius of the hole we do some calculations based on the image of the hole on the screen however the calculations are mathematically highly complex and must assume that the object s hole projects an image resembling an ellipse if the tube is not parallel to the screen in the centre of the screen however it is unlikely that the object is placed so conveniently firstly we must transform the major and minor axis of the ellipse i cannot know what the angle between the tube and screen is do i have to assume that they are parallel to do the transformation how do i do this transformation secondly there is a distortion of the image due to the screen being planar the source screen distance increases as we move away from the centre of the screen how can i compensate the ellipse s axis for this image distortion so please can anyone give us a few pointers here how do we transform the image so it appears as it would if it were in the centre of the screen and how do i deal with distortion due to the shape of the screen we d appreciate any help either posted or emailed thanks in advance simon simon marshall dept of computer science university of hull hull hu rx uk football isn t about life and death it s more important than that bill email s marshall cs hull ac uk phone fax shankley
