TechDisc
A golf disc with built-in sensors that measures speed, spin, nose, hyzer and launch angles and wobble. Works with a net indoors, and comes with a companion app and a flight simulator.
techdisc.comUser guide
Flight Plate Monitor
Measure the speed, spin, launch angle, nose angle, hyzer angle and wobble of your disc golf throws with a phone lying on the ground. This page has the pattern to print and the how-to videos.
1. Print the pattern
The printed calibration pattern goes on the underside of your disc. In the app, tap Info and then the disc icon to open the PDF, or download it here.
Download the pattern (PDF)Print at actual size (100 %). Untick “Fit to page” and any other scaling option in the print dialogue. Then check the print with a ruler: neighbouring shapes are 40 mm apart, centre to centre, and the outermost shapes 80 mm apart. A scaled print makes the speed readings wrong.
Cut the pattern out and stick it flat on the underside of the disc, as close to the centre as you can. The app measures where the spin centre is relative to the pattern, so small offsets do not matter.
2. Calibrate the camera
Calibration measures your phone camera's focal length and lens distortion. It is done once per phone, with the printed pattern and the Flight Plate Control app on a second phone guiding you through the poses.
English
Suomeksi
3. Measure your throws
Lay the phone on the ground with the camera facing up and press Start. Throw over the phone so that the disc passes about 1 to 1.7 m above it, travelling along the longer direction of the view (top to bottom or bottom to top on the screen, not sideways). The app detects each throw by itself and reads out the results. Open Throws to look at saved throws in detail.
You need an Android phone that supports 120 fps high-speed video at 1280 × 720.
English
Suomeksi
Established launch monitors
Flight Plate Monitor grew out of my interest in the measurement problem, and it was inspired by these commercial products. It is not meant to replace them. If you want a mature, supported product, look at these first:
RipReader
A phone app for iOS and Android that tracks throw speed, spin and distance without any extra hardware, with slow-motion video and GPS distance.
ripreaderapp.comHow it works
The measurement method, from the retrained disc detector to the rolling-shutter physics fit, is described on the projects page.