In the real world, a camera is a device that takes physical or digital photos. In the virtual world, it is used to aim at virtual objects and or move through a virtual scene.
Physical Camera
A camera is a device that records images that can be stored directly, transmitted to another location, or both. These images may be still photographs or moving images such as videos or movies.
A digital camera is a kind of camera that takes video or still photographs by recording images on an electronic image sensor. Most cameras sold today are digital, and are incorporated into many devices ranging from PDAs and mobile phones to vehicles.
An Internet protocol camera, or IP camera, is a type of digital video camera commonly employed for surveillance, and which unlike analog closed circuit television (CCTV) cameras can send and receive data via computer network and the Internet.
A webcam is similar to an IP camera, but is normally connected directly to a computer via fast physical connection (USB, FireWire, etc).
Virtual Cameras
Much as real-life cameras provide a view of a scene in the real world, a virtual camera system provides a view of scene in virtual worlds. In 3D video games, a virtual camera system aims at controlling a camera or a set of cameras to display a view of a 3D virtual world. These virtual camera systems are often used in video games, where their purpose is to show the action at the best possible angle; more generally, they are used in 3D virtual worlds when a third person view is required.
Cameras in Computer Vision
An important application for cameras in the context of programming is in the field of computer vision. In particular, development of algorithms and code for the purpose of recognition, motion analysis, scene reconstruction, image restoration and so forth. The camera parameters, calibration and references to other cameras are significant factors in these algorithms.
