Abstract
Line triangulation already displays important features of a ‘perfect’ single-shot principle but lacks high data density. Hence, current line triangulation sensors, like Flying Triangulation, are far away from being ‘perfect’. The reason is the profound ambiguity problem. The majority of measurement principles (see Chap. 3) buys correlation information by sacrificing feature and data resolution or/and temporal resolution.
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Notes
- 1.
To memorize: The big advantage of single-shot principles is that the exposure time for a 3D height map is uncoupled from the camera frame rate. Assuming flash exposure with sufficient light, the exposure time for a 3D height map can be principally very short, even if the time for a single camera frame is much larger.
- 2.
Of course, only from a hardware-based point of view the information is ‘for free’. From the information-theoretical point it is not, as a second camera picture is acquired.
- 3.
Note, that this is the reason why the back-projection-approach is not related to active stereo approaches.
- 4.
Cameras with equal hardware (chip and optics) as well as perfectly overlapping fields assumed.
- 5.
Figures related to the simulation were provided by Christian Faber, now at University of Applied Sciences, Landshut, Germany.
- 6.
This is quite trivial, since the surface point \((x_i,y_i,z_i)\) is the ‘origin’ of the gray value \(I(x_i,y_i,z_i)\).
- 7.
Each projected line has a certain width and each back projection is evaluated in a certain search region (see Sect. 5.1.1) to compensate for noise and calibration errors, which means that outliers can also be located slightly beneath a ray of sight to be considered as correct points.
- 8.
Within the limits of the sampling theorem.
- 9.
At least for the telecentric case, which is used for the theoretical considerations. For non-telecentric setups, there is a small perspective effect, which is negligible in most cases. It can be avoided by the application of a beam splitter.
- 10.
Note: a free-viewpoint 3D movie is not related to cinema ‘3D movies’, which should be better considered as ‘2.5D movies’. Such movies only simulate a 3D impression by offering the audience two slightly different pictures, which represent the different pictures in each eye. No real 3D data are present. The 3D evaluation is performed in the human brain. Moreover, the viewpoint of each scene is always fixed and cannot be chosen freely.
- 11.
To be precise, the triangulation angle, enclosed by the second camera and the projection should not be zero. Unfortunately this is approximately the case in the Flying Triangulation face scanner, where the signal-back-projection-approach has only a reduced effect. See [1, 6] for more in information.
- 12.
As long as the back projections of ‘correct points’ are landing inside the Gauß-correlation area of the corresponding line, no additional neighborhood information is exploited.
- 13.
Nevertheless, a switchable projector is included in the prototype setup to test different numbers of projected lines. It can be replaced by a chrome on glass slide projector for a ‘final version’ of the single-shot 3D movie camera.
References
F. Willomitzer, FlyFace – 3D-Gesichtsvermessung mittels “Flying Triangulation”. Diploma Thesis, University Erlangen-Nuremberg (2010)
O. Arold, Flying Triangulation’ - handgeführte optische 3D Messung in Echtzeit. Dissertation, University Erlangen-Nuremberg (2013)
F. Willomitzer, S. Ettl, C. Faber, G. Häusler, Single-shot three-dimensional sensing with improved data density. Appl. Opt. 54(3), 408–417 (2015)
F. Willomitzer, S. Ettl, C. Faber, G. Häusler, Detection and correction of line indexing ambiguities in Flying Triangulation. in Proceedings of the 114th DGaO Conference, A12 (2013)
F. Willomitzer, S. Ettl, C. Faber, G. Häusler, Flying Triangulation - Towards the 3D Movie Camera. in Fringe 2013 (Springer, Heidelberg, 2013), pp. 895–898
M. Kuch, Neue Indizierungsmethoden für die Multilinientriangulation. Master Thesis, University Erlangen-Nuremberg (2014)
G. Häusler, F. Willomitzer, P. Dienstbier, C. Faber, Tomographic Triangulation. in Proceedings of the 114th DGaO Conference, A16 (abstract only) (2013)
F. Willomitzer, G. Häusler, Single-shot 3D motion picture camera with a dense point cloud. Opt. Exp. 25(19), 23451–23464 (2017)
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Willomitzer, F. (2019). Solving the Problem with an Additional Source of Information . In: Single-Shot 3D Sensing Close to Physical Limits and Information Limits. Springer Theses. Springer, Cham. https://doi.org/10.1007/978-3-030-10904-2_5
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