Automatic measurement of the hand dimensions using consumer 3D cameras

Abstract

<p class="Abstract">This article describes the metrological characterisation of two prototypes that use the point clouds acquired by consumer 3D cameras for the measurement of the human hand geometrical parameters. The initial part of the work is focused on the general description of algorithms that allow for the derivation of dimensional parameters of the hand. Algorithms were tested on data acquired using Microsoft Kinect v2 and Intel RealSense D400 series sensors. The accuracy of the proposed measurement methods has been evaluated in different tests aiming to identify bias errors deriving from point-cloud inaccuracy and at the identification of the effect of the hand pressure and the wrist flexion/extension. Results evidenced an accuracy better than 1 mm in the identification of the hand’s linear dimension and better than 20 cm<sup>3 </sup>for hand volume measurements. The relative uncertainty of linear dimensions, areas, and volumes was in the range of 1-10 %. Measurements performed with the Intel RealSense D400 were, on average, more repeatable than those performed with Microsoft Kinect. The uncertainty values limit the use of these devices to applications where the requested accuracy is larger than 5 % (volume measurements), 3 % (area measurements), and 1 mm (hands’ linear dimensions and thickness).</p>

3D shape measurement techniques for human body reconstruction

“…This technique is based on the time of flight [29] measurements, that is the time taken by an object, a particle or a wave to travel a certain distance. More specifically, LiDAR emits a pulse or modulated light signal and measures the time difference in the returning wavefront [25], [30]; this allows estimating distance from signal propagation speed. c) Structured Light scanner (SL): this technology is based on the projection of a known light pattern (grid) on the object and, according to the deformation of this projected grid on the curved surface of the object, reconstructs its geometry.…”