The two cameras photograph the same target from two points at a certain distance. The overlapping images are called stereo images. A necessary condition for a stereo image pair is that the image overlapping degree is greater than 53%.
Two remote sensing images will be arranged side by side. If the left eye looks at the image on the left and the right eye looks at the image on the right, it will produce the stereoscopic visual effect of the target object, which is called stereoscopic observation. The human eye can observe the objective world with a stereoscopy. The principle is that when an eye is observing an object, there is a physiological parallax between the images produced by the object on the retina of both eyes.
Likewise, for a pair of images of the same object from different angles, there is an image parallax similar to the physiological parallax, which is called the Left and Right Parallax.
When both eyes observe this image, the image with the Left and Right Parallax is reflected on the retina of the eyes, which forms the physiological Parallax,
This produces the same stereoscopic visual effect as when observing objects. It is usually said that under such conditions, the three-dimensional image is observed, and the three-dimensional feeling is taken as a man-made three-dimensional observation.
This is the basic principle of three-dimensional observation using aerial images.