Image tiling for a high-resolution helmet-mounted display

Abstract

Head-mounted or helmet-mounted displays (HMDs) have long proven invaluable for many military applications. Integrated with head position, orientation, and/or eye-tracking sensors, HMDs can be powerful tools for training. For such training applications as flight simulation, HMDs need to be lightweight and compact with good center-of-gravity characteristics, and must display realistic full-color imagery with eye-limited resolution and large field-of-view (FOV) so that the pilot sees a truly realistic out-the-window scene. Under bright illumination, the resolution of the eye is ~300 r (1 arc-min), setting the minimum HMD resolution. There are several methods of achieving this resolution, including increasing the number of individual pixels on a CRT or LCD display, thereby increasing the size, weight, and complexity of the HMD; dithering the image to provide an apparent resolution increase at the cost of reduced frame rate; and tiling normal resolution subimages into a single, larger high-resolution image. Physical Optics Corporation (POC) is developing a 5120 4096 pixel HMD covering 1500 1200 mr with resolution of 300 r by tiling 20 subimages, each of which has a resolution of 1024 1024 pixels, in a 5 4 array. We present theory and results of our preliminary development of this HMD, resulting in a 4k 1k image tiled from 16 subimages, each with resolution 512 512, in an 8 2 array.

A practical definition of eye-limited display system resolution

“…This assumption is pervasive enough that many make the assertion in discussions, proposals, and training courses with no further explanation or citation. Others who use the term this way provide the explanation that 1 arcmin is the stroke and gap width for the symbols on the common Snellen acuity charts for 20/20 vision and conclude that a display resolution of one arcmin is required [1][2][3][4][5][6][7][8][9][10] .…”