Abstract: An apparatus, method, and system for measuring a golf club swing motion, especially a golf putting stroke, from the overhead view and enabling to provide in-situ athletic training and instruction along with analysis of the putting stroke by using augmented reality superimposed on the image of the actual golf club. The system comprises a portable apparatus, mobile device application interface, image processing algorithms and network servers. The portable apparatus includes a mini-camera and communication modules for capturing the video image of a putting stroke and transmitting the image via wireless, Wi-Fi, Hotspot, or Bluetooth to a designated electronic display device such as a tablet, mobile phone, or laptop. The portable apparatus is fixed to a fastening clip which fits easily onto a golf cap to provide the overhead view of the putting stroke and record the image from an actual golf course.