Interactive Blood Flow Velocity Simulation

Web App Overview

This interactive simulation demonstrates the principles of estimating two-dimensional blood flow velocity from video, inspired by the research presented by the Multimedia Computing Research Laboratory (MCRLab) at uOttawa. The original research shows how subtle, invisible color changes in human skin, caused by blood circulation, can be amplified and analyzed to reveal physiological information like heart rate and blood flow patterns.

This simulation creates a synthetic "skin patch" where you can observe these principles in action. You can control the heart rate, magnify the color changes, and switch between different visualization modes to understand the process from raw signal to a final velocity field map.

How to Use

• Play/Pause: Start or stop the simulation.
• Reset: Return all parameters to their default state.
• Play Demo: Watch an automated demonstration that cycles through all features and visualization modes.
• Heart Rate Slider: Adjust the beats per minute (BPM) of the synthetic heart pulse.
• Visualization Mode:
  • Magnified Video: Simulates the Eulerian Video Magnification technique. The subtle color pulse is amplified, making the "heartbeat" visible.
  • Amplitude Map: Shows the strength of the pulse signal at each point. Brighter areas indicate a stronger signal (more blood vessels).
  • Phase Map: Visualizes the timing of the pulse. The color (hue) represents the phase, showing how the pulse wave travels across the area.
  • Velocity Field: The final output. Arrows show the computed direction and magnitude of the blood flow based on the phase differences between adjacent points.
• Magnification Slider: Controls the amplification factor for the "Magnified Video" mode. Higher values make the color change more pronounced.
• Artifacts Toggle: Simulates noise and artifacts that can occur in real-world recordings (e.g., "halo" artifacts from motion, random noise). Toggling this on helps visualize the challenges in the process. The velocity field calculation includes steps to mitigate these artifacts.
• Sound Toggle: Enables sonification. The average pulse intensity is converted into an audible "thump," allowing you to hear the simulated heart rate. Sound is off by default.

The simulation is fully responsive and can be controlled with a mouse, keyboard (use Tab and Enter/Space), or touch gestures.

Future Directions

While this simulation provides a solid foundation for understanding the core concepts, future enhancements could include:

• User-Uploaded Video: Allowing users to upload their own short video clips for analysis, moving from synthetic data to real-world application.
• More Complex Flow Patterns: Introducing more intricate synthetic data models, such as bifurcating vessels or turbulent flow areas.
• Quantitative Data Overlay: Displaying real-time numerical data, such as the calculated average velocity or BPM, directly on the canvas.
• Advanced Artifact Simulation: Adding more types of noise, like lighting changes or compression artifacts, and implementing more sophisticated filtering techniques.