Design and quality metrics of point patterns for coded structured light illumination with diffractive optical elements in optical 3D sensors

Abstract

Structured light has become a widespread technique for the development of camera-based 3D sensors. The structured illumination provides texture to homogeneous objects and thus allows for the reliable determination of the disparity of each object point in a stereo-camera setting. Even a monocular 3D sensor is possible if the light projector has a fixed relative position to the camera and if the structured light is coded, i.e. the position within the whole light pattern can be reconstructed uniquely from a small local window of the pattern, the uniqueness window. Coded patterns with such a uniqueness property are called Perfect SubMaps (PSM).In our paper we focus on the design and evaluation of the subset of symmetric isolated binary toroidal PSMs (SIBTPSM) for structured light patterns, because of their beneficial properties with respect to the signal-to-noise ratio and the use with laser light sources and DOEs. We define several figures of merit that are relevant for the practical use of PSMs in a 3D sensor: the PSM size, the size of the uniqueness window, the Hamming distance, the density, and the homogeneity. We have created SIBTPSMs using our own dedicated algorithms and have designed and fabricated DOEs that produce these patterns with large fan angles of 61• × 47• when used with near-infrared diode lasers (λ = 830nm). We analyze the influence of these characteristics on the 3D measurement process by theory, simulations, and experiments. The patterns of publicly available DOEs based on SIBTPSMs are used for comparison and reference.Our results show that the PSM width, the uniqueness window size, the minimum and average Hamming distances, and the uniformity have strong impact on either speed or quality of the 3D reconstruction, whereas the point density and the PSM height are of minor importance.

Polka Lines: Learning Structured Illumination and Reconstruction for Active Stereo

“…However, this heuristic design is blind to scene statistics, noise level, and the reconstruction method. Existing methods have attempted to improve depth estimation by employing hand-crafted DOE designs [11,49,34] that rely on golden-eye experts and heuristic metrics on the illumination pattern, not directly correspond to system depth accuracy. We depart from these heuristic designs and instead directly optimize the illumination pattern with the final depth reconstruction accuracy as a loss via end-to-end optimization.…”

P2.05 - Entwurf einer universellen tastenlosen optischen Fernbedienung

“…Zur Sicherstellung einer Reichweite von mehreren Metern verwendet das hier beschriebene System aus Kostenund Aufwandsgründen eine NIR-Laserdiode (Wellenlänge 905 nm) in Kombination mit einer Kollimator-Linse und einem Diffraktiven Optischen Element (DOE). Mit dem DOE wird aus dem geeignet aufgeweiteten Laserstrahl mittels einer als Beugungsgitter wirkenden mikrostrukturierten Oberfläche eine Punktmatrix von bis zu mehreren Tausend Punkten erzeugt [12,13]. Neben der festzulegenden Laser-Wellenlänge sind die Größe und die statistische Anordnung der Beugungspunkte wesentliche Designparameter des DOE.…”

One-Shot M-Array Pattern Based on Coded Structured Light for Three-Dimensional Object Reconstruction

“…e use of colors reduced the size of the windows. Vandenhouten et al [13] focused on the design and evaluation of a subset of symmetric isolated binary toroidal perfect submaps for structured light patterns, and several valuable images related to the practical application of perfect submaps in a 3D sensor were defined. A 20 × 20 M-array and window property of 3 × 3 was designed by Pagès et al [14], based on an alphabet of three symbols.…”