golftracker 0.0.4

Use open cv to detect critical elements in a golf swing.

Introduction

This package detects the various elements in a golf swing. It does this by tracking various points in the swing and writing the coordinates into a json file for later processing.

No single algorithm can generate all the trackers in a frame. Hence multiple algorithms are run, which creates multiple json files per frame. These are then merged to create a single composite json file per frame.

The various algorithm used are

• Google Media Pipe Pose Detection This detects 33 pose landmarks. These are written into json files with filename <frame_fname>_mp.json

• Use the script golfeditor in this package to mark the position of the ball and the club head initially. Then run the cv2 tracking algorithms to track the movements of these across multiple frames. The trackers tracked by this are

  1. Club Grip: This is where the hands are holding the club shaft.
  2. Club Heel: This is shown in this diagram
  3. Club Toe : Shown here
  4. Position of the golf ball.

Detailed src documentation of this package is on ReadTheDocs

Installation

This is a standard python package and follows the typical flow for installing python packages.

python -m venv env_test_tracker

// Activate the virtual env
// On Windows run  env_test_tracker/Scripts/activate
// On Linux bash source env_test_tracker/Scripts/activate.sh

pip install golftracker

To run the example below you would also need another utility package thatI use for video file manipulations.

pip install spvidoeutils

Development

The source repository is in GitHub. The development flow is similar to other python projects.

• Clone the project.
• Create a virtual env and install all the dependencies
• Install the package locally in dev mode.

Distribution

This is a pure python code package and so a wheel distribution is sufficient. My typical steps are below.

• Bump the version in setup.py
• Build the distribution

python setup.py bdist_wheel

• Upload the distribution

twine upload dist/*

Example

I downloaded a video of michelle wei swing side view and used the following flow to create the tracker.

The shortened copy of the video is also on my shared drive as https://drive.google.com/file/d/16TaL8PSaK46wbXr7mVsDZLbpOieLC3Nm/view?usp=sharing

Let's save/rename it as test1.mp4 for the steps below.

Step1: Split the video into frames

From the package spvideoutils, run the script video_split to create a subdir test1 that will have all the frames.

video_split test1.mp4

Step2: Run Google media script to create json

Run the command below to create the json file for the trackers by google pose detection.

pose_detection test1

Step3: Run golf detection tracker.

For this the first step is to use the script golfeditor to manually select the club grip, club heel and club toe of the first frame.

Use the following keywords to select the corresponding tracker. Press 's' to save to json

Key	Description
b	ball selected
g	club grip
h	club heel
t	club toe
s	save to json

golfeditor test1

This step allows the user to create the json file by hand.

Trackers

The following points are tracked on each frame as points with co ordindates (x,y). They are written into a json file for further analysis.

• Ball Position This is the point at which the ball is placed. It is assumed that the target is directly towards it.

• Club Shaft Position The start of the club is where the hands grasp the shaft and the end is where the club head is

Json Output

A sample json output is shown below for a frame with width=1024 and height=900. The coordinates assume that left top is the origin.

The ball is placed at (100, 200). The hand holding the shaft is at (10, 20) and the club head is at (30, 40)

{
    "frame" : [1024, 900]
	  "ball": [1, 2],
	  "shaft": [10, 20, 30, 40]
}