Table 2 Procedures and their representative methods

Background observation

Pre-observation

[13, 25, 26, 49–51]

Active self-observation

[12, 16, 17]

Real-time observation

[6, 14, 27, 29–33, 40, 41, 46]

Combination

[19, 27, 45]

Scene tracking

Fixed viewpoint

[6, 52]

Constrained viewpoint

[16, 17]

Free viewpoint

[9, 10, 13, 14, 21–23, 25, 26, 35, 36, 38, 41, 43, 49, 107]

Region of interest detection

Overlay without detection

[41]

Manual detection

[6, 29, 33, 34, 37, 40, 48]

(Semi-)Automatic detection

[9, 10, 13, 14, 16, 17, 21–23, 25, 26, 31, 38, 39, 46, 47, 49, 59]

Hidden view generation

Homography

[13, 19, 35, 36, 42]

3D reconstruction

[6, 14, 29, 31, 40, 43]

Image-based rendering

[25, 26, 30, 49, 66, 67, 107]

Inpainting

[9, 10, 21–23]

Composition

Seamless blending

[13, 25, 26, 31, 38, 49]

Semi-transparent representation

[33, 34, 45–48, 71–77]

AR overlay

[4, 20, 25, 49, 78]