How good does the VR visual display need to be?

Three crucial factors for the display are:

1. Spatial resolution: How many pixels per square area are needed?
2. Intensity resolution and range: How many intensity values can be produced, and what are the minimum and maximum intensity values?
3. Temporal resolution: How fast do displays need to change their pixels?

The spatial resolution factor will be addressed in the next paragraph. The second factor could also be called color resolution and range because the intensity values of each red, green, or blue subpixel produce points in the space of colors; see Section 6.3. Recall the range of intensities from Figure 5.4 that trigger photoreceptors. Photoreceptors can span seven orders of magnitude of light intensity. However, displays have only 256 intensity levels per color to cover this range. Entering scotopic vision mode does not even seem possible using current display technology because of the high intensity resolution needed at extremely low light levels. Temporal resolution is extremely important, but is deferred until Section 6.2, in the context of motion perception.

Figure 5.22: (a) Due to pixels, we obtain a bad case of the jaggies (more formally known as aliasing) instead of sharp, straight lines. (Figure from Wikipedia user Jmf145.) (b) In the screen-door effect, a black grid is visible around the pixels.