pandaxbacon / hawkeye

A perception system for ball tracking in cricket and tennis.

HawkeyeNet

Motivation

A perception system for ball tracking in cricket and tennis. Watch these short videos to understand what a hawkeye does in tennis and cricket.

The above systems cost millions of dollars, and are only available to professional sports players at the world's top stadiums. The goal of this work is to bring a (less powerful) version of this system to everyday recreational players via a smartphone camera.

Technical Details

The model consists of a recurrent neural network augmented with a YOLO-like network. The YOLO-like network is pre-trained by framing ball tracking as a regression problem. The recurrent units enable us to take advantage of spatio-temporal properties of ball tracking in sports.

The training is performed by using a fixed set of base images and generating stochastic ball trajectory sequences (similar to data augmentation). The thus generated (image, label) frames are used for training.

The system can track cricket and tennis balls using a smartphone camera (much lower resolution than professional sports cameras used for Hawkeye systems in stadiums), from a distance, in the presence of motion blur, varied backgrounds and occlusion, while being able to run on a mobile device.

This model has been ported to Tensorflow Eager, which gives us a better Pythonic expression of the model (define-by-run as opposed to define-and-run) and makes it easier to debug in many cases.

Instructions to run locally

1. Collect a dataset with images that contain backgrounds representative of your use case (I trained it on a variety of backgrounds. I will be releasing the dataset I used soon).
2. pip install tf-nightly (we need nightly builds for TF Eager unless you have >=1.5)
3. python main.py --pretrain-cnn to pretrain they YOLO like network. python main.py to train the whole system.

Future work

1. Train across multiple sports to see if we can get a better overall model.

2. I will be working on building a UI and deploying this to an Android app to take it out to the field and use it in my cricket matches. Once I've fine-tuned it, the goal is to publish this and make it accessible in the App Store.