Another way to think about resolution, however, is relative to the field of view the pixels are spread across. The total number of pixels matters, of course, but the density of the pixels matters as well, and it’s here that VR faces some unique issues. Let’s run some numbers on that.

My very first game ran on a monitor that I’d estimate to have a horizontal field of view of maybe 15 degrees at a normal viewing distance. At 160×72, that’s about 11 pixels per horizontal degree.

A 30” monitor at 2560×1600 has about a 50-degree field of view at a normal viewing distance. That’s roughly 50 pixels per horizontal degree, and approximately the same is true of a 20” monitor at 1600×1200.

The first consumer VR head-mounted displays should have fields of view that are no less than a 90 degrees, and I’d hope for more, because field of view is key to a truly immersive experience. At 960×1080 resolution, that yields slightly less than 11 pixels per horizontal degree – the same horizontal pixel density as the CP/M machine I wrote my first game for in 1980, and barely one-fifth of the horizontal pixel density we routinely use now.