Depth map is a hotspot in computer vision research field. With the development and promotion of 3D display equipment

depth map extraction methods have attracted considerable attention. This study reviews the development trend of depth map extraction and summarizes the existing methods. Classifications are adopted on the basis of depth cues and human-computer interaction degree. The existing methods are grouped into three categories

namely

monocular

binocular

and multiple depth cue-based types. These methods are then classified into three schemes based on different human-computer interactions

namely

manual

semi-automatic

and automatic. This study focuses on the basic principles of these methods and emphasizes their advantages and limitations. A detailed analysis is also performed based on the application and development of machine learning methods for depth extraction. Future developments in depth extraction

including the adoption of new methods and the introduction of new depth cues

are discussed.