Design of a polarized head-mounted projection display using ferroelectric liquid-crystal-on-silicon microdisplays

2013 IEEE Virtual Reality (VR)

2013

One of the problems in using head-mounted displays (HMDs) is that the virtual images shown through the HMDs are usually distorted due to their optical distortions. In order to correctly compensate the optical distortions through a predistortion technique, accurate values of the distortion parameters are required. Although several distortion calibration methods have been developed in prior work, these methods suffer a few critical limitations. In this paper, we proposed a method for robustly estimating the optical distortion parameters of both immersive and (optical) see-through HMDs, without the limitations of existing methods. The proposed method is based on photogrammetry and considers not only the radial distortion but also the tangential distortion. Its effectiveness was evaluated through an experiment conducted with two different types of HMDs, an optical seethrough head-mounted projection display and a commercially available non-see-through HMD. According to the experimental results, the proposed method showed significantly lower reprojection error than a previous method proposed by Owen et al. In addition, when both the radial and tangential distortions were considered, the proposed method was significantly more effective than when only the radial distortion was considered.

Section: Methodsmentioning

confidence: 99%

A robust camera-based method for optical distortion calibration of head-mounted displays

Lee

2013 IEEE Virtual Reality (VR)

2013

“…Consider an HMPD system [33] developed in our lab and used in this experiment (see Fig. 3 for its configuration).…”

Section: Ray-shift Phenomenonmentioning

confidence: 99%

Effects of Optical Combiner and IPD Change for Convergence on Near-Field Depth Perception in an Optical See-Through HMD

Lee

IEEE Trans. Visual. Comput. Graphics

2016

Self Cite

Many error sources have been explored in regards to the depth perception problem in augmented reality environments using optical see-through head-mounted displays (OST-HMDs). Nonetheless, two error sources are commonly neglected: the ray-shift phenomenon and the change in interpupillary distance (IPD). The first source of error arises from the difference in refraction for virtual and see-through optical paths caused by an optical combiner, which is required of OST-HMDs. The second occurs from the change in the viewer's IPD due to eye convergence. In this paper, we analyze the effects of these two error sources on near-field depth perception and propose methods to compensate for these two types of errors. Furthermore, we investigate their effectiveness through an experiment comparing the conditions with and without our error compensation methods applied. In our experiment, participants estimated the egocentric depth of a virtual and a physical object located at seven different near-field distances (40∼200 cm) using a perceptual matching task. Although the experimental results showed different patterns depending on the target distance, the results demonstrated that the near-field depth perception error can be effectively reduced to a very small level (at most 1 percent error) by compensating for the two mentioned error sources.

“…An in-house developed binocular HMPD prototype was employed in this study [6]. The prototype employed a pair of Ferroelectric Liquid Crystal on Silicon (FLCoS) microdisplays as the image source, providing a FOV of 55º in an angular resolution of 2.1 minutes of arc and a pixel resolution of 1280x1024 pixels.…”

Section: Experimental Setup and System Calibrationmentioning

confidence: 99%

“…Designing a wide field-of-view (FOV), compact and non-intrusive optical see-through HMDs, however, has been challenging. To address the challenge, head-mounted projection display (HMPD) technology has recently been explored extensively as an alternative approach to conventional OST-HMD designs [2][3][4][5][6][7]. Figure 1 shows a monocular schematic design of an HMPD, where the light from an image source is projected by a projection lens and is reflected by a beamsplitter towards a retroreflective screen.…”

Section: Introductionmentioning

confidence: 99%

Effects of a retroreflective screen on depth perception in a head-mounted projection display

Zhang

2010 IEEE International Symposium on Mixed and Augmented Reality

2010

Self Cite

The perceived depth accuracy is a fundamental performance metrics for an augmented reality display system. Many factors may affect the perceived depth of a head-mounted display (HMD), such as display resolution, interpupillary distance (IPD), conflicting depth cues, stereoacuity, and head tracking error. Besides these typical limiting factors to an HMD-type system, the perceived depth through a head-mounted projection display (HMPD) may be further affected by the usage of a retroreflective screen. In this paper, we will evaluate the perceived depth accuracy of an HMPD system using a perceptual depth matching method. The main factor to be investigated in our study is the position of a retroreflective screen relative to the projection image plane, with the projection image plane placed at different distances to the user. Overall, it is found that the ratio of the judged distance to real distance and the standard deviation of the judged distance increase linearly with the reference object distance. A transition effect from depth underestimation to overestimation has been observed at the reference object distance of around 1.4m. The position of a retroreflective screen only has a significant effect on the depth judgment error around this switching point. The paper also analyzes various effects brought by a retroreflective screen on the depth judgment. The depth cue and the image luminance reduction brought by a retroreflective screen could be the main factors that affect the depth judgment accuracy.