This Privacy Policy describes how the 3D Seg/Joint Angles iOS application ("the App", "we", "our") handles information in connection with your use of the App. We are committed to protecting your privacy and being transparent about our practices.
By using the App, you acknowledge that you have read and understood this Privacy Policy. If you do not agree with this policy, please discontinue use of the App.
3D Seg/Joint Angles is a biomechanics measurement tool designed to compute and display three-dimensional Cardan/Euler angles of body segments and joints using your iPhone's built-in inertial measurement unit (IMU). It is intended for use in clinical, research, rehabilitation, and educational settings. The App is not a medical device and is not intended to diagnose, treat, cure, or prevent any medical condition.
The App does not collect, transmit, or store any of the following:
The App requests access to your device's motion hardware, which includes:
These sensors are accessed through Apple's CoreMotion framework (CMMotionManager) solely to compute three-dimensional rotation matrices and Cardan/Euler angles in real time. The App uses sensor fusion (combining accelerometer, gyroscope, and magnetometer data) to derive device orientation relative to a user-defined reference position.
You will be prompted by iOS for permission to access motion and fitness activity data before the App can function. You may revoke this permission at any time via Settings → Privacy & Security → Motion & Fitness. Revoking permission will prevent the App from computing angles.
The App includes an optional recording feature that temporarily stores time-stamped angle measurements (X, Y, Z axes in degrees) in device memory during an active recording session. This data:
You may choose to export recorded data as a Comma-Separated Values (CSV) file using iOS's standard Share Sheet. The CSV file contains only time and angle columns - no personal or identifying information. Once you share the file, it is handled entirely by the destination app or service you select (e.g., Mail, Files, AirDrop, cloud storage). The developer has no access to exported files. You are solely responsible for how exported data is stored, shared, or used after leaving the App.
The App does not require an internet connection to function and makes no network requests whatsoever. It does not connect to any backend server, API, or external service. There is no user account creation, login, authentication, or cloud synchronization of any kind.
The App does not integrate any third-party SDKs, libraries, analytics platforms, advertising networks, or crash-reporting services. The only frameworks used are Apple's own first-party system frameworks:
These frameworks are governed exclusively by Apple's privacy practices and terms of service.
The App is distributed through Apple's App Store and is subject to Apple's standard platform privacy practices. Apple may collect certain aggregated, non-identifiable data related to App Store downloads and usage in accordance with Apple's Privacy Policy. The developer has no access to individually identifiable data through Apple's developer tools.
The App is not directed to children under the age of 13 (or 16 in certain jurisdictions). We do not knowingly collect any personal information from children. Because the App collects no personal information from any user regardless of age, it presents no heightened privacy risk to minors. If you have concerns about a child's use of this App, please contact us at daiboyi@gmail.com.
Because the App does not collect, store, or transmit any personal data, the risk of a data breach or unauthorized access through the App is negligible. All computation occurs locally on your device, which is protected by iOS's built-in security architecture, including hardware-level encryption, app sandboxing, and process isolation.
If you export angle data via the Share Sheet, the security of that file depends on the destination platform or service you choose. We recommend using secure, password-protected channels if the data is clinically sensitive.
The App retains no data beyond the current session. Recorded angle values are held in RAM only while the App is running and are immediately discarded when the App is terminated or a new session begins. No log files, databases, caches, or documents are created by the App on your device's permanent storage.
Because no personal data is collected, there is no personal data to access, correct, delete, or export on our end. However, you retain full control over your own device and any CSV files you have exported. Depending on your jurisdiction, you may have rights under applicable privacy laws. If you have questions, contact us at daiboyi@gmail.com and we will respond within a reasonable timeframe.
Although the App does not collect personal data, it is designed to be consistent with the principles of major privacy frameworks:
3D Seg/Joint Angles is intended for research, educational, and general biomechanics purposes only. It is not a certified medical device and has not been evaluated by the FDA, CE, or any other regulatory body. Measurements provided by the App should not be used as the sole basis for clinical diagnosis or treatment decisions. Users in clinical settings are responsible for ensuring appropriate use and compliance with applicable regulations.
We may update this Privacy Policy from time to time to reflect changes in the App or applicable law. Changes will be posted at this URL with an updated "Last Updated" date. We encourage you to review this page periodically. Continued use of the App after changes are posted constitutes your acceptance of the updated policy. Material changes will also be noted in the App Store version release notes.
If you have any questions, concerns, or requests regarding this Privacy Policy or the App's data practices, please contact:
Boyi Dai
Email: daiboyi@gmail.com
We aim to respond to all privacy-related inquiries within 7 business days.