Representing Virtual Transparent Objects on Optical See-Through Head-Mounted Displays Based on Human Vision

In this study, we propose two methods for representing virtual transparent objects convincingly on an optical see-through head-mounted display without the use of an attenuation function or shielding environmental light. The first method represents the shadows and caustics of virtual transparent objects as illusionary images. Using this illusion-based approach, shadows can be represented without blocking the luminance produced by the real environment, and caustics are represented by adding the luminance of the environment to the produced shadow. In the second method, the visual effects that occur in each individual image of a transparent object are represented as surface, refraction, and reflection images by considering human binocular movement. The visual effects produced by this method reflect the disparities among the vergence and defocus of accommodation associated with the respective images. When reproducing the disparity, each parallax image is calculated in real time using a polygon-based method, whereas when reproducing the defocus, image processing is applied to blur each image and consider the user’s gaze image. To validate these approaches, we conducted experiments to evaluate the realism of the virtual transparent objects produced by each method. The results revealed that both methods produced virtual transparent objects with improved realism.