Collecting Bat Tracking Data

While our Data Collection Principles remain applicable when collecting bat tracking data, there are some additional considerations to make prior to recording data for bat tracking:

Camera Setup

Ensure cameras capture the entire swing volume and full bat arc from multiple angles, focusing on visibility of the hands and both ends of the bat. When setting up a camera system for bat tracking it is important to consider the following points for both left- and right-handed athletes, and it is beneficial to have someone stand within the capture volume in both positions during setup.

• In some cases, the hands and base of the bat can be obscured by the head and torso of the athlete in the pre-swing 'ready' position. Slightly elevated cameras and/or cameras that are more aligned with the pitching direction (both in front of and behind the athlete) can improve this visibility.

• The tip of the bat can travel in a large radius arc around the athlete. Ensure that the tip of the bat will remain within the camera views throughout the swing, for a wide range of athlete sizes and positions relative to the strike zone.

• Given the speed of the movement, batting typically requires the use of high frame rates and reduced image resolution. As such, it is important to position the cameras as close to the athlete as possible to capture them with sufficient resolution.

Lighting

Maintain bright and even illumination to minimize motion blur and improve athlete and bat visibility.

Attire and Equipment

Wherever possible, avoid attire and equipment (gloves, bat) that provides limited contrast against each other and the background. Before collecting data, confirm that the hands and both ends of the bat remain visible to multiple cameras throughout the swing. Using attire and equipment that provide strong contrast can improve the visibility of the segments and improve bat tracking performance.

The most important elements to consider include:

• Background

• Athlete attire

• Gloves

• Bat

Camera Settings

Batting can be a very fast movement with high velocities and accelerations, therefore it is important that the cameras are configured to record videos that capture the movement smoothly and clearly.

Adjust the frame rate and exposure or shutter speed accordingly, to ensure the athlete's body segments and the bat move smoothly between subsequent video frames, and there is minimal motion blur.

Netting

For markerless motion capture applications such as batting that require protective netting, it is important to consider its impacts on the video data quality. Consider the following when setting up or adapting a capture volume for bat tracking:

• Knotless, minimal thickness twine is recommended to reduce the visual impacts of netting on the video data and athlete visibility. See the example comparing netting styles.

• Wherever possible, use such netting for the entire protective boundary; otherwise, patch sections of existing netting in front of each camera's field of view.

Examples of protective netting, including 1.2 mm knotless twine (left, preferred) and standard gauge knotted twine (right).