Combined 3D, multispectral, and fluorescence imaging through design of an integrated structural light scanner |
Kristian Ryder Thomsen
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| Abstract | The goal of the thesis is to design a system for measuring 3D simultaneously with spectral image recording in the VideometerLab4 instrument, develop analysis algorithms to exploit the combined 3D and spectral information, and to demonstrate that this can be utilized efficiently in 1-3 applications. The possible approaches for designing such an integrated 3D measurement system are discussed and evaluated and an in-depth analysis made of selected types of structured light solutions and time-of-flight technology. A variant of phase shifting profilometry based on Fourier analysis is selected as the most suitable method given the system specifications. The problem of phase unwrapping is also studied and a dual-wavelength solution selected. Algorithms for triangulation of points in 3D space are discussed and a computationally effective algorithm is derived. The extended acquisition time for additional 3D measurements are just 0.6 seconds. The accuracy of the systems 3D reconstructions are analysed and the height error found to be normally distributed around zero with a standard deviation of just 34.7 micrometers. The lateral uncertainty is 25.9 micrometers. An accurate and robust stereo calibration is explained and performed with sub-pixel accuracy for both the camera and the projector. Lastly two specific applications of combined 3D and spectral data are introduced and evaluated. First a novel algorithm is presented for classification of grains orientation into the categories of either dorsal or ventral and it is shown to be statistically significantly outperforming the 2D alternative. Segmentation of granular products, such as rice, grains or seeds, are also studied and a modification to the existing 2D approach presented that are expected to increase the number of correctly segmented grains by 1.5%. |
| Type | Master's thesis [Industrial collaboration] |
| Year | 2016 |
| Publisher | Technical University of Denmark, Department of Applied Mathematics and Computer Science |
| Address | Richard Petersens Plads, Building 324, DK-2800 Kgs. Lyngby, Denmark, compute@compute.dtu.dk |
| Series | DTU Compute M.Sc.-2016 |
| Note | DTU supervisors: Jens Michael Carstensen, jmca@dtu.dk (DTU Compute) and Anders Bjorholm Dahl, abda@dtu.dk (DTU Compute). Industrial cooperator: Videometer A/S |
| Electronic version(s) | [pdf] |
| Publication link | http://www.compute.dtu.dk/English.aspx |
| BibTeX data | [bibtex] |
| IMM Group(s) | Image Analysis & Computer Graphics |