3D reconstruction is a method by which an object is re-created within a virtual, three-dimensional (3D) space using a computer. This can be done in a number of different ways, but usually involves the use of input data such as two-dimensional (2D) photographs or the scanning of the actual object. Once this 3D reconstruction is created, then it can be manipulated or utilized in a number of different ways, including for medical uses, law enforcement reconstructions, and even the creation of 3D graphics for film or television.
The creation of a 3D reconstruction usually involves digital image professionals, rather than 3D computer modelers, as the images are not usually created as much as they are assembled. There are two basic approaches to this type of reconstruction that can be used, based on how those involved gather the input data for the reconstruction. Active reconstruction involves some form of interference between the object being reconstructed and a sensor, such as scanning an object or taking photographs of it. Passive 3D reconstruction, on the other hand, uses sensors that receive data without interfering with the object at all, such as devices used to receive light from distant stars.
This input data can then be used to create a 3D reconstruction of the original object or objects. A scan of a person’s body, for example, can be used to create a 3D model of that person in a computer system. Passive scans from distant stars could similarly be used to create a 3D model of a far away galaxy or to create an animated sequence showing the movement of different stars in virtual space.
Medical uses of 3D reconstruction are quite extensive, especially when used with magnetic resonance imaging (MRI) equipment that allows medical professionals to see a 3D model of a brain without performing surgery. These reconstructions are also used for a number of different reasons in law enforcement. A 2D photograph can be used to create a 3D model of a person to more accurately depict what he or she may look like, and even a skull can be used to perform such reconstructions.
3D computer graphics for film and television can also utilize this type of 3D reconstruction to create more realistic images. A scan of an actor, for example, can be used to create a highly realistic 3D model of that actor, which is then used to create a digital stuntman who can perform stunts that might be impossible for a person to do. Reconstructions are often used to create realistic 3D models of environments or objects, such as cars, to create images for commercials that are more perfect than reality.