Data Collection Principles
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Theia Axiom - v2025
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The following guidelines describe data collection best practices, but are not exhaustive. You may obtain high quality markerless motion capture data under different conditions from those described below.
Camera system setups differ from location to location, and may be subject to challenging data collection environment constraints. General recommendations for setting up your camera system include:
Cameras as close as possible to the capture volume, while ensuring the entire capture volume remains within view for all cameras.
Cameras 4-8 feet (1-2.5 m) above the ground.
Avoid partial views of subjects, such as lower body or upper body only.
Avoid unusual camera views, especially those positioned very high or very low, or extremely tilted.
Aim for a symmetrical camera setup that surrounds the entire capture volume, such as a circle, oval, or rectangle.
The camera settings you choose will depend on the movements being collected. Selection of appropriate camera settings is crucial for collecting clear, crisp video images. The most important camera settings to consider include:
Frame rate: fast movements require high frame rates, to capture the movement smoothly. Check out this for discussion and recommendations.
Shutter speed / Exposure: should be set to ensure the subject and their body segments are not blurry during the movement. Faster shutter speeds or shorter exposures will capture images with less movement blur, but may reduce the image brightness.
If you are collecting high-speed movements, you may need to consider introducing additional light into your capture volume in order to capture videos that are adequately bright. In general, faster movements require higher frame rates, faster shutter speeds / shorter exposures, and more light. Check out this blog post for more details on .
Theia3D provides 3D pose estimates that are robust to changes in attire. General recommendations for subject attire include:
Body-fitting clothing. Each limb should be discernible from the rest of the body.
Clothing should provide rich visual features, such as visible creasing, shadows, or other textures.
Lighting is often more important than attire color, as it impacts the visual richness of the attire. Under adequate lighting conditions black attire is acceptable, but lighter colors generally provide more visual features, especially in low-light environments.