Method for Parametric Evaluation of 3-D Surface Imaging Systems for Applications With Moving Objects

Medical applications in which patient movements are tracked with 3-D surface imaging systems are becoming increasingly popular. The 3-D imaging systems used for such applications must be able to cope with controlled and uncontrolled motions of the human body. The key factors for producing a high-quality 3-D representation of the moving human body are the spatial resolution, accuracy, and precision of the 3-D imaging system. To our knowledge, no international standard yet exists to assess these parameters. In this article, we propose a phantom model, a method, and parameters for the assessment of spatial resolution, accuracy, and precision to evaluate systems for the 3-D imaging of moving objects. The proposed phantom model is an extension of the standard 1951 USAF resolution test chart to 3-D and consists of two parallel staircases with varying step heights. The phantom model is actuated with an industrial robot. The application of our method to the Photoneo MotionCam-3-D showed that their multishot structured-light mode has a higher accuracy for static and slowly moving objects (accuracy of 0.1 mm) than their single-shot structured-light mode (accuracy of 0.5 mm). However, the single-shot mode can capture fast-moving objects without much loss of accuracy and precision. This provides practical quantifications for the Photoneo MotionCam-3-D. Furthermore, this confirms that the proposed phantom model, method, and parameters can be used as part of a standard to assess the spatial resolution, accuracy, and precision of systems for the 3-D imaging of moving objects.