Introduction to stereoscopy

Stereoscopy is a technique used to create the perception of depth when viewing stereoscopic images. Our two eyes enable us to experience a three-dimensional world, caused by the small perspective differences between the left and right eyes. These are interpreted by the brain as “depth”. The perception of depth is called stereopsis. With stereoscopy it is possible to simulate this process.

The most popular way to create stereoscopic images is with a camera. With a conventional camera, stereoscopic images are made by taking one photo, slightly shifting the position of the camera and then taking a second photo. The distance between both positions is called the stereo baseline. The result is two nearly identical photos with only a slight difference in perspective caused by the two different camera positions, similar to the different positions of our eyes. These two pictures form a stereo pair. A stereo camera has two lenses, which are mounted at some distance from each other. With a stereo camera, the two photos can be made simultaneously, without having to move the camera position. The main advantage compared with conventional cameras is that stereo cameras prevent motion between the two photo captures.

A developed stereo photo is called a stereoview. There are several ways to view a stereoview in 3-D. The most commonly used method is by using a stereoscopic viewer, better known as a stereoscope. The stereoview is placed in the stereoscope, and both images of the stereoview can be viewed through the two lenses: the left image with the left eye and the right image with the right eye. This process allows the viewer to see the image in 3D.