In recent years, virtual reality (VR) technology has taken the world by storm. All it takes is a headset, and suddenly, you might find yourself at the bottom of the ocean, the farthest reaches of space, or travelling the globe as if you were actually there. While VR’s success has been the result of a series of impressive technological innovations, it also depends on how effectively our eyes can process virtual images and convince our brains we’re having a real experience. This is no small task, and in fact, VR incorporates several visual concepts in order to create compelling virtual worlds in front of us.

The principle that underlies VR is that of stereoscopic vision, which allows humans to perceive depth and distance. Thanks to stereoscopic vision, each of our eyes sees similar but different images than our other eye—this phenomenon is known as retinal disparity—and the brain processes these images by matching the images while accounting for the slight differences, which creates visual depth. VR headsets replicate stereoscopic vision by displaying two sets of images at different angles, which causes the brain to interpret the images as an open world and not a flat screen.

VR further creates the illusion of depth (and thus visual authenticity) through the use of parallax effects, which cause objects that are farther from you to appear smaller and move slower, image shading, and other techniques.

Effective VR headsets and software must also consider field of view (FOV). Humans have an FOV of about 180 degrees while looking straight ahead and about 270 degrees when the eyes move, so headsets must come close to replicating this visual range or users will be able to see the real world intrude into their virtual experience.

Another key element of vision and VR is latency, or the time between an action or motion and a response to it. For example, if you move while wearing your headset, the latency would be the time that it took the device to detect that motion and display new images accordingly. Latency can be affected by a number of factors, such as the processor used in the headset, and poor latency can cause the user to think that their world is moving either too fast or too slow.