Measuring surface profile of golf clubs, calibrating image capture device and apparatus for preparing a measurement specimen by taking a cast of a surface

摘要

There is described a method and apparatus for testing a surface of a golf club to determine conformance or otherwise with at least one of the requirements of the Rules of Golf. The apparatus comprises a moulding dam (7) for producing a moulded sample / cast (20) having a surface corresponding to the surface to be measured, and a cutting apparatus (23) for cutting a specimen or "slice" from the moulded sample / cast. An image of a profile of the specimen / slice is captured and dimensions of features of the surface profile of the golf club determined from the captured image. The specification also discloses apparatus and a method for calibrating an image capture device in order to produce a dimensionally accurate trace of a profile of a surface from a captured pixellated image of the profile. The method of calibration involves capturing a pixellated image of a calibration grid, detecting pixel co-ordinates of predetermined points on the image, determining distance between selected pairs of points, determining local scale factors for a number of points on the captured image by comparing pixel distances associated with those points with known dimensions of the calibration grid; predicting scale factors for pixels of the captured image on the basis of the predetermined scale factors and applying the predicted scale factors to pixels of the image to convert pixel co-ordinate data to dimensional co-ordinate data. The step of predicting scale factors may comprise generating an nth degree polynomial equation to relate local scale factors to pixel co-ordinates and finding polynomial coefficients which best fit the measured scale factor values and their associated pixel co-ordinate data. The polynomial is then applied at each pixel location to determine a scale factor for that location.