Volumetric description of dip solder joints from range data

Dip solder joints exhibit a variety of complex shapes, making inspection by traditional representation methods difficult. Traditional approaches use various features of 2D images to represent joint shape; however, correct 3-D representation is essential when analyzing joint shape for visual inspection. We present a method of using generalized cylinders (GCs) to obtain a 3-D representation of a solder joint from the joint´s range image. This method is based on symmetry detection. B-spline contour representation allows analytical detection of a symmetry axis that is used as a basis for the GC axis. In addition, we present a B-spline fitting method that uses an initial line fitting procedure. The contour of the cross section is expressed as an ellipse using an ellipse-specified conic fitting method. Correct representations for over 53 test sample range images were obtained