Effect of Surface Shape on the Readability of Projected Characters and Its Readability Improvement by Moving Characters in Projection-Based Annotations

Abstract

Through two psychophysical studies, we investigate the effect of the shape of a projection surface on the readability of projected characters from a PC projector. The first study was designed based on a paired comparison test. As a result, we found that the depth amplitude was correlated to the readability of projected characters. The legibility was significantly decreased when the frequency was 2 cycles per a character width. In a previous work, we found the readability of a projected character was improved when it was moving. In this paper, we investigate the effect of the speed and distance of the movement on the readability of projected characters. Through the second study, we found the readability was improved when the speed was more than 2/3 of character's width and when the distance was more than a wavelength of the surface. The results of this research would be useful in automatic view management of projection based annotations.