How to start new tracking?
Why app fails to recognize court or recognition is not stable?
Why automatic ball recognition failed?
Why speed is displayed in orange?
How to perform manual tracking?
Why marking server or bounce point positions doesn't work?

How to start new tracking?

Click "Start new Tracking" panel on a home screen to perform new tennis serve speed mesure. Position your camera and adjust it's field of view according to the image below. Application should capture the court position and start indicating it on preview by drawing green lines alone the court & net boundaries. If it's the case then you're ready for serve tracking, otherwise read Why app fails to recognize court or recognition is not stable?



Once a consistent court position tracking is detected by app the camera preview caption will change to "Touch screen to begin...". Once you touch the screen the video will start recording and tennis serve must be executed within allocated time period (video recording time limit is indicated on caption and configurable in settings). The video recording will end if you tap the screen again or it reaches time limit. To abort current tracking (serve fault for example) click "back" button. Once recording finished the actual processing will start and will last around 2-4 seconds. It's done on the video instead of the camera preview because most devices do not provide consistent frame rate during camera preview, only on video.


Why app fails to recognize court or recognition is not stable?

"Tennis Serve Tracker" is recognizing court position almost 100%. Actually, testing it in multiple conditions and locations we never had it failed - at the end without stable court recognition you can't do any tracking! Try to follow simple steps below in order to resolve this problem:

  • Make sure to position camera as explained and shown above;
  • Try to move camera slowly when searching for a court and do not shake it;
  • App is using "auto focus" camera feature if available. Make sure it's focused on the court;
  • Try to move to another court if possible;
  • If it's still not working make court picture and send it to us to investigate.

Why automatic ball recognition failed?

In outdoor conditions with natural light ball recognition success is over 90%. There are multiple factors that can prevent successful ball recognition, but if you try to eliminate most common your success rate will be higher:

  • poor light conditions (indoor or artificial light is not sufficient);
  • keep recognition video short and do not move camera off or around a recognized court during recording;
  • use relatively new balls with distinct standard "optic yellow" color;
  • travelling service ball path background contains a lot of yelow color noise, for example multiple balls lying in the service box or yellow wall behind the server;
  • poor mobile camera hardware;
  • rule of thumb - if you can barely see the ball on the video frame it's practically impossible to do it in the app!

Why speed is displayed in orange?

If speed is displayed in orange it means server position adjustment for automatic tracking or ball positions for manual tracking are required to finalize recogniton. For automatic adjust sever position using "server" player control - long touch the button to start drag-n-drop operation and drop it on a server. App player will pre-roll the video to the correct frame when service had started. For a manual mark 2 ball positions - when racket hits the ball and when ball hits the court. When done click "calculate" to perform final speed calculation.


How to perform manual tracking?

When automatic recogniton failed (read Why automatic ball recognition failed?), app will allow you to perform manual recogniton. All you have to do is to mark 2 ball positions - when racket hits the ball and ball hits the court. When finished click "calculate" button to calculate speed. Use pan and zoom player functionality for better precision.



Why marking server or ball positions doesn't work?

Depending of the deuce or ad serve you're trying to mark server or ball positions outside of allowed boundaries. For example, marking server position on a deuce court side will not work for an ad serve; or marking bounce point way outside the service box boundaries.


"Tennis Serve Tracker" app has several screens and settings that are explained in details below, but here's a brief overview. First of all it's a "Start new Tracking" screen that performs recognition. There is a custom video player that allows you to review your tennis serve in frame by frame stepping mode with panning & zooming features. You can navigate and manage your previous serve speed mesurements using a "History" screen and a context dependent "Quick Tips" will provide additional help and information within an app.