3D computer graphics 3D computer graphics, or “3D graphics,” sometimes called CGI, 3D-CGI or three-dimensional computer graphics are graphics that use a three-dimensional representation of geometric data (often Cartesian) that is stored in the computer for th ...

and

computer vision Computer vision is an interdisciplinary scientific field that deals with how computers can gain high-level understanding from digital images or videos. From the perspective of engineering, it seeks to understand and automate tasks that the human ...

, a depth map is an

image An image is a visual representation of something. It can be two-dimensional, three-dimensional, or somehow otherwise feed into the visual system to convey information. An image can be an artifact, such as a photograph or other two-dimensio ...

or image channel that contains information relating to the distance of the surfaces of scene objects from a viewpoint. The term is related (and may be analogous) to ''depth buffer'', ''Z-buffer'', '' Z-buffering'', and ''Z-depth''. tp://ftp.futurenet.co.uk/pub/arts/Glossary.pdf Computer Arts / 3D World Glossary Document retrieved 26 January 2011. The "Z" in these latter terms relates to a convention that the central axis of view of a

camera A camera is an optical instrument that can capture an image. Most cameras can capture 2D images, with some more advanced models being able to capture 3D images. At a basic level, most cameras consist of sealed boxes (the camera body), with ...

is in the direction of the camera's Z axis, and not to the absolute Z axis of a scene.

Examples

File:Cubic Structure.jpg, Cubic Structure File:Cubic Frame Stucture and Floor Depth Map.jpg, Depth Map: Nearer is darker File:Cubic Structure and Floor Depth Map with Front and Back Delimitation.jpg, Depth Map: Nearer the Focal Plane is darker Two different depth maps can be seen here, together with the original model from which they are derived. The first depth map shows luminance in proportion to the distance from the camera. Nearer surfaces are darker; further surfaces are lighter. The second depth map shows luminance in relation to the distances from a nominal focal plane. Surfaces closer to the

focal plane In Gaussian optics, the cardinal points consist of three pairs of points located on the optical axis of a rotationally symmetric, focal, optical system. These are the '' focal points'', the principal points, and the nodal points. For ''ideal'' ...

are darker; surfaces further from the focal plane are lighter, (both closer to and also further away from the viewpoint).

Uses

Cubic Structure with Shallow Depth of Field

Depth maps have a number of uses, including: * Simulating the effect of uniformly dense semi- transparent media within a scene - such as fog, smoke or large volumes of water. * Simulating shallow depths of field - where some parts of a scene appear to be out of focus. Depth maps can be used to selectively blur an image to varying degrees. A shallow depth of field can be a characteristic of

macro photography Macro photography (or photomacrography or macrography, and sometimes macrophotography) is extreme close-up photography, usually of very small subjects and living organisms like insects, in which the size of the subject in the photograph is grea ...

and so the technique may form a part of the process of

miniature faking Miniature faking, also known as diorama effect or diorama illusion, is a process in which a photograph of a life-size location or object is made to look like a photograph of a miniature scale model. Blurring parts of the photo simulates the shal ...

. * Z-buffering and z-culling, techniques which can be used to make the rendering of 3D scenes more efficient. They can be used to identify objects hidden from view and which may therefore be ignored for some rendering purposes. This is particularly important in real time applications such as computer games, where a fast succession of completed renders must be available in time to be displayed at a regular and fixed rate. * Shadow mapping - part of one process used to create shadows cast by illumination in 3D computer graphics. In this use, the depth maps are calculated from the perspective of the lights, not the viewer. * To provide the distance information needed to create and generate autostereograms and in other related applications intended to create the illusion of 3D viewing through

stereoscopy Stereoscopy (also called stereoscopics, or stereo imaging) is a technique for creating or enhancing the illusion of depth in an image by means of stereopsis for binocular vision. The word ''stereoscopy'' derives . Any stereoscopic image i ...

. * Subsurface scattering - can be used as part of a process for adding realism by simulating the semi-transparent properties of translucent materials such as human skin. * In

single-view or multi-view images depth maps, or other types of images, are used to model 3D shapes or reconstruct them. Depth maps can be generated by

3D scanner 3D scanning is the process of analyzing a real-world object or environment to collect data on its shape and possibly its appearance (e.g. color). The collected data can then be used to construct digital 3D models. A 3D scanner can be based on m ...

s or reconstructed from multiple images. * In

Machine vision Machine vision (MV) is the technology and methods used to provide imaging-based automatic inspection and analysis for such applications as automatic inspection, process control, and robot guidance, usually in industry. Machine vision refers to ...

and computer vision, to allow 3D images to be processed by 2D image tools. Synthesizing 3D Shapes via Modeling Multi-View Depth Maps and Silhouettes With Deep Generative Networks

Synthesizing 3D Shapes via Modeling Multi-View Depth Maps and Silhouettes With Deep Generative Networks

* Making depth image datasets.{{Cite journal, last1=Mousavi, first1=Seyed Muhammad Hossein, last2=Mirinezhad, first2=S. Younes, date=January 2021, title=Iranian kinect face database (IKFDB): a color-depth based face database collected by kinect v.2 sensor, journal=SN Applied Sciences, volume=3, issue=1, doi=10.1007/s42452-020-03999-y, issn=2523-3963, doi-access=free

Limitations

* Single channel depth maps record the first surface seen, and so cannot display information about those surfaces seen or refracted through transparent objects, or reflected in mirrors. This can limit their use in accurately simulating depth of field or fog effects. * Single channel depth maps cannot convey multiple distances where they occur within the view of a single pixel. This may occur where more than one object occupies the location of that pixel. This could be the case - for example - with models featuring hair, fur or grass. More generally, edges of objects may be ambiguously described where they partially cover a pixel. * Depending on the intended use of a depth map, it may be useful or necessary to encode the map at higher bit depths. For example, an 8 bit depth map can only represent a range of up to 256 different distances. * Depending on how they are generated, depth maps may represent the perpendicular distance between an object and the plane of the scene camera. For example, a scene camera pointing directly at - and perpendicular to - a flat surface may record a uniform distance for the whole surface. In this case, geometrically, the actual distances from the camera to the areas of the plane surface seen in the corners of the image are greater than the distances to the central area. For many applications, however, this discrepancy is not a significant issue.

Examples

Uses

Limitations

References

See also