Simultaneous Direct and Augmented View Distortion Calibration of Optical See-Through Head-Mounted Displays

In Augmented Reality (AR) with an Optical See-Through Head-Mounted Display (OST-HMD), the spatial calibration between a user's eye and the display screen is a crucial issue in realizing seamless AR experiences. A successful calibration hinges upon proper modeling of the display system which is conceptually broken down into an eye part and an HMD part. This paper breaks the HMD part down even further to investigate optical aberration issues. The display optics causes two different optical aberrations that degrade the calibration quality: the distortion of incoming light from the physical world, and that of light from the image source of the HMD. While methods exist for correcting either of the two distortions independently, there is, to our knowledge, no method which corrects for both simultaneously. This paper proposes a calibration method that corrects both of the two distortions simultaneously for an arbitrary eye position given an OST-HMD system. We expand a light-field (LF) correction approach [8] originally designed for the former distortion. Our method is camera-based and has an offline learning and an online correction step. We verify our method in exemplary calibrations of two different OST-HMDs: a professional and a consumer OST-HMD. The results show that our method significantly improves the calibration quality compared to a conventional method with the accuracy comparable to 20/50 visual acuity. The results also indicate that only by correcting both the distortions simultaneously can improve the quality.