I'm bad at seeing serves in or out - problem is from the returners POV the 3d tennis ball overlaps the 2d white line and space between.
It's impossible to see the distance between the service T and ball when it's close as it's blocked by the ball.
You can try to "train" your eye to better judge out balls. Set a tennis ball ever slightly behind the line - go to return position and study how much overlap there is of ball to line. Any ball that bounces with this much overlap of the line or more is out.
Also have a partner randomly put a ball on or near the line and try to guess if it's in or out and you will hopefully be able to judge better.
Still tough when you only get a split second view and get the ball flying at high speeds.
It's impossible to see the distance between the service T and ball when it's close as it's blocked by the ball.
You can try to "train" your eye to better judge out balls. Set a tennis ball ever slightly behind the line - go to return position and study how much overlap there is of ball to line. Any ball that bounces with this much overlap of the line or more is out.
Also have a partner randomly put a ball on or near the line and try to guess if it's in or out and you will hopefully be able to judge better.
Still tough when you only get a split second view and get the ball flying at high speeds.
