A user-guidance system that utilizes augmented-reality (AR) components and human-posture-detection techniques is presented. The user-guidance system can help users to use smart devices to conduct 3D body scans more efficiently and accurately. AR components are computer generated for the on-screen guidance to guide a camera operator to position the camera in a particular location in relation to a target object with a particular tilt orientation in relation to the target object to capture an image that includes a region of the target object for 3D reconstruction of the target object. Human-posture-detection techniques are used to detect a human user's real-time posture and provide real-time on-screen guidance feedback and instructions to the human user to adopt an intended best posture for 3D reconstruction of the human user.
