# Camera System Requirements This section describes the basic camera system requirements for recording data to be used with Theia3D. See [Data Collection](/apollo-v2024/theia3d-documentation/data-collection.md) for additional recommendations and principles to follow when recording video data for Theia3D. ## Number of Cameras Theia3D requires a minimum of six cameras for tracking; however, we recommend a minimum of eight cameras for most capture volumes. The number of cameras required will increase with movement complexity, capture volume size, capture volume complexity, and the number of people to be tracked. The field of view and joint visibility requirements outlined below are the best guides when determining the number of cameras required for a specific capture volume. ## Synchronization and Video Duration The cameras must capture synchronous videos with identical start times and durations to be used with Theia3D. ## Field of View Person identification and tracking perform best when the people of interest are fully visible and cover a large percentage of the fields of view of the cameras. In most applications a height of 500 pixels is adequate - this requirement may increase based on camera setup, focus, and image quality. It is important that the people of interest are in focus and clearly visible. ## Joint Visibility Ideal tracking conditions are achieved when all joints are visible in all cameras; however, this is rarely attainable due to occlusions from other limbs, people, and the environment. At a minimum, each joint must be visible in at least three cameras. When setting up the cameras it is important to position and orient the cameras in a way that minimizes occlusions while simultaneously providing views of the subject(s) from varying angles to improve joint depth and position calculations. For example, a purely sagittal view results in several occlusions and poor tracking from that view but provides useful information for identify the depth of joints tracked in a more frontal view. ## Subject Clothing Theia3D does not require people to wear specific clothing to be tracked. However, loose or baggy clothing may result in lower quality tracking. As a general rule, if you can easily identify joints in the camera images, then Theia3D can infer the joint positions as well. --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://docs.theiamarkerless.com/apollo-v2024/theia3d-documentation/camera-system-requirements.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.