Perceptual Translucency in 3D Printing Using Surface Texture.

We propose a method of reproducing perceptual translucency in three-dimensional printing. In contrast to most conventional methods, which reproduce the physical properties of translucency, we focus on the perceptual aspects of translucency. Humans are known to rely on simple cues to perceive translucency, and we develop a method of reproducing these cues using the gradation of surface textures. Textures are designed to reproduce the intensity distribution of the shading and thus provide a cue for the perception of translucency. In creating textures, we adopt computer graphics to develop an image-based optimization method. We validate the effectiveness of the method through subjective evaluation experiments using three-dimensionally printed objects. The results of the validation suggest that the proposed method using texture may increase perceptual translucency under specific conditions. As a method for translucent 3D printing, our method has the limitation that it depends on the observation conditions; however, it provides knowledge to the field of perception that the human visual system can be cheated by only surface textures.

A Circumference-Measurement Method Using a Model of a Leg and a 3D Camera.

The circumference of a limb is an important parameter in the follow-up of an edema. Recently, several methods of measuring the circumference on a limb using 3D cameras have been proposed. However, the 3D cameras used are expensive and difficult to implement in general medical facilities. In this study, we propose a circumference-measurement method using a Structure Sensor. First, the leg is photographed and unnecessary background objects are removed from the obtained point cloud. Next, a cross-sectional view is obtained by slicing the point cloud at the specified leg height. Finally, the circumference measurement at a specified leg height is performed by calculating the circumference using the acquired cross-sectional view. Using this method, the leg circumferences of two healthy subjects were measured at two points. For comparison, circumferences were also measured with a measuring tape. The difference between the values estimated using our method and the measured values was generally less than 0.5 cm.