Lights, Camera, Motion Capture!

Optimize video capture for biomechanical analysis.

Written by
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Naimar Ramirez-Batlle
Published on
December 11, 2024

You don't need expensive equipment to start using the Factorial Biomechanics analysis platform. A simple smartphone, tablet, or action camera can capture high-quality video for analysis. To optimize your process, we have prepared guidelines to effectively capture and analyze human movement using readily available technology.

Here’s the TL;DR: To ensure optimal results, prioritize camera stability, adequate lighting, and appropriate camera distance and angle. Consider the type of movement being analyzed when selecting the frame rate and resolution. Higher frame rates are ideal for fast movements, while lower frame rates are sufficient for slower ones. Additionally, using a remote control, reviewing and editing footage, and storing it securely will enhance the overall process.

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Photo by Alan Quirván

GOOD TO KNOW

You don’t need any special hardware to use Factorial Biomechanics.

You can load video taken by just about any camera ⎯ however, we recommend you keep the below guidelines in mind.

These guidelines can be applied to all videography, but we’re focusing on entry-level tech you probably already have: a smartphone, tablet or laptop webcam, or an action camera, like the GoPro.

What about your camera model?

The camera you already have will do, at least for now ⎯ as you improve, you can upgrade or expand your set-up.

The camera, no matter how expensive, is not going to make a great video for motion analysis by itself. In the guidelines we’ll cover topics that will help you capture better videos, like stability, lighting, image resolution, frames per second selection, distance from the subject, and camera position and orientation.

VIDEO CAPTURE GUIDELINES

Lets dive in!

Camera stability

  • Tripod or stable surface: A tripod is essential for minimizing camera shake, ensuring smooth and steady footage. If a tripod isn't available, consider using a stable surface like a table or a sturdy stand.
  • Steady hand grip: While a steady hand grip can be sufficient for short clips, using a tripod or other stabilizing device is recommended for longer recordings and more precise analysis.

Lighting

  • Bright and diffused light: Adequate lighting is crucial for capturing detailed video. Avoid backlighting and ensure the subject is well-lit.

    • Please note: “Office lighting” is usually OK, but some fluorescent lights as well as some LEDs might show flickering in video that is not visible to the naked eye. This is most common when recording at high FPS (we’ll get into FPS in a bit).

  • Additional light source: Consider using an additional light source, such as an LED floodlight, to improve visibility in low-light conditions, especially when capturing indoor or nighttime footage.

    • Please note: A battery operated LED flood light, set up below the camera, and pointed at the subject can add an incredible amount of detail to the video, and enhance your analysis. You can get a good quality one starting around $20, at a big box or hardware store.

Camera distance and angle

  • Optimal distance: Aim for a distance of around 4 meters (13ft) between the camera and the subject to capture sufficient detail. However, the best distance for you depends on the space you’re working with, your equipment, and the motions to be measured.
    • Portrait orientation: Best for static or limited movement, such as weightlifting, balance exercises, or upper body movements.
    • Landscape orientation: Ideal for capturing linear motion, like walking, running, jumping, or any movement that involves a significant horizontal displacement.
  • Choosing a lens: If you have a smartphone with multiple lenses, go with the narrowest that will fit your space and motion.
    • Telephoto lens: For capturing fine details, a telephoto lens can be beneficial. However, it may require more light and distance from the subject.
    • Wide-angle lens: While wide-angle lenses can capture a wider field of view and require less light, they can introduce distortion at the edges of the frame.

Framing

  • Plain background: A plain background can help to isolate the subject and simplify the analysis process.
  • Reference markers: Consider using reference markers, such as a yardstick or lines on the floor, to aid in measurements and calculations.

Frame rate

Most smartphones allow you to choose from 30, 60, 120, and 240 frames per second. Default is usually 30fps, and 60fps is sometimes described as high speed. “Slow motion” allows you to choose from 120fps and 240fps, sometimes shown as 1/4x and 1/8x, which is the rate at which the action is slowed. Slow motion video tends to be encoded at 30fps, slowing the action down instead of packing more action into less time, so you should take note of the frame rate chosen if measuring speed of motion.

  • Higher frame rate: A higher frame rate (e.g., 120fps or 240 fps) allows for more detailed analysis of movement, especially for rapid or complex movements, but requires about double the amount of light you would use for regular video.
  • 30fps will work perfectly for many tests, including RoM, FMS and Senior Fitness.
  • 60fps can be better for gait analysis, and spasticity.
  • 120-240fps will be necessary for running, throwing and swinging actions.

Resolution

Each camera/phone model will allow a different combination of fps and resolution (the amount of pixels in each still of the video). GoPro Hero 11 for example will allow 240fps at full hd 1080p and 2.7K but only 60fps at UHD 4k and super high res 5.3k.

  • Sufficient resolution: Choose a resolution that captures the necessary level of detail for your analysis. A higher resolution may be required for precise measurements, particularly when analyzing small-scale movements.
  • Balance frame rate and resolution: Consider the trade-off between frame rate and resolution. A higher frame rate may require a lower resolution to maintain video quality, especially in low-light conditions.

Additional tips

  • Use a remote control: A remote control allows you to start and stop recording without disturbing the subject.
  • Review and edit your footage: Review your footage to identify any issues with lighting, framing, or motion blur. Use video editing software to trim, crop, and enhance your videos. If you recorded a long session, trim or crop your video into smaller movement sequences for easy analysis.
  • Store your footage: Store your video footage in a safe and organized manner. Use a reliable storage solution, such as an external hard drive or cloud storage, to prevent data loss.

By following these guidelines, you can capture high-quality video footage that will provide valuable insights into human movement. Remember to experiment with different camera setups and settings to find the optimal configuration for your specific needs.

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Naimar Ramirez-Batlle

Naimar is a co-founder, CMO and Head of Marketing and Customer Success at Factorial Biomechanics.