Using astigmatism in wide angle HMDs to improve rendering

Lenses in modern consumer HMDs introduce distortions like astigmatism: only the center area of the displayed content can be perceived sharp while with increasing distance from the center the image gets out of focus. We show with three new approaches that this undesired side effect can be used in a positive way to save calculations in blurry areas. For example, using sampling maps to lower the detail in areas where the image is blurred through astigmatism, increases performance by a factor of 2 to 3. Further, we introduce a new calibration of user-specific viewing parameters that increase the performance by about 20-75%.