The measurement of geometric objects such as circles, ellipses, rectangles or lines is an important task and a frequently asked question. A convenient solution to deal with this task is the metrology model. By means of the metrology model, it is possible to measure the exact shape parameters of the geometric objects that should be inspected. This method provides robust results even for adverse conditions, when measuring noisy, disturbed or low contrast edges.
The metrology model is a widely used tool, which is available since HALCON 11. However, in HALCON 12 the metrology model has been extended by several new operators, which simplify the use of the metrology model such as align_metrology_model.
The operator align_metrology_model rotates and translates the whole metrology model in order to align the model with the object in the current image. An alignment ensures that the position and orientation of the metrology model is adapted to the objects to be measured. The combination of align_metrology_model with other methods such as shape-based matching leads to an easy way to measure geometric objects in different aligned parts.
The visualization of the metrology model has also been simplified in HALCON 12. The new operator get_metrology_object_model_contour returns the contours of the metrology objects and the operator get_metrology_object_result_contour returns the contours of the approximated geometric forms. The operator get_metrology_object_result now allows to get the edge points that were used during the fitting of the geometric forms.
Last but not least, it is now possible to add any kind of geometric forms (circle, ellipse, rectangle, line) to a metrology model by means of the operator add_metrology_object_generic. A quick overview about the discussed operators can be obtained in the standard example measure_stamping_part.hdev.