Interactive Polygon Drawer for Video Frames

This Python script allows users to interactively draw multiple polygons on video frames using the mouse and view the results in real-time. It is useful for applications like annotating regions of interest (ROIs) in videos for computer vision tasks.

Features

• Load a video file for annotation.
• Use the mouse to add points to form polygons.
• Real-time drawing of polygons on the video frames.
• Create and manage multiple polygons using intuitive controls.
• Pause and resume video playback using the Space key (drawing allowed only while paused).
• Undo the last point added to the current polygon with the U key.
• Save the current polygon and start a new one using the N key.
• Quit the application using the Q key.
• Display all collected polygon points at the end of the session.
• Save the polygons as a JSON file for further use.

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Getting Started

Prerequisites

• Python 3.x
• OpenCV library (cv2)
• NumPy library (numpy)

You can install the required libraries using pip:

pip install opencv-python-headless numpy

Installation

1. Clone this repository or download the script.
2. Replace video_path with the path to your video file.

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Usage

1. Run the script:

   python3 Createzones.py

2. Annotate:
   • Use Left Mouse Click to add points for the current polygon while the video is paused.
   • Press N to save the current polygon and start a new one.
   • Press U to undo the last point added to the current polygon.
   • All polygons will be displayed on the video frames when the video is resumed.
3. Controls:
   • Press Q to quit.
   • Press Space to toggle between pause and resume (drawing is only allowed when paused).
4. Save Polygons:
   • After finishing annotation, the polygons are automatically saved to a JSON file.
   • The JSON file contains all the polygon data, which can be used for future processing.

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Code Overview

Key Components

• Mouse Callback: Adds points to the current polygon when the left mouse button is clicked, but only when the video is paused.
• Pause/Resume: The Space key is used to pause and resume video playback. While paused, users can draw polygons.
• Multiple Polygon Management: Save the current polygon and begin a new one using the N key.
• Undo Functionality: Use the U key to undo the last point added to the current polygon while paused.
• Video Playback: Displays video frames in a resizable window.
• Polygon Drawing: Dynamically renders each polygon as points are added, but only when the video is paused.
• JSON Saving: The polygon data is saved to a polygons.json file at the end of the session.

Example Output

The console prints the polygon points in the format:

Point Added: (X: 100, Y: 200)
Polygon Completed:
X: 100, Y: 200
X: 150, Y: 250
...

JSON File Format

The polygons are saved as a JSON file in the following format:

[
    [[100, 200], [150, 250], [200, 200], ...],
    [[300, 400], [350, 450], [400, 400], ...],
    ...
]

Each polygon is represented as an array of points, and all polygons are stored in a list.

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Future Enhancements

• Add functionality to save the polygon data to a file.
• Support for drawing closed polygons by default.
• Add support for exporting the video with annotated polygons.

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License

This project is licensed under the MIT License.

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Enjoy annotating your videos with multiple regions of interest! 🎥