High-speed pattern projection for three-dimensional shape measurement using laser speckles

Abstract

We propose a high-speed projection system that is able to project statistical speckle patterns at a rate of 500Hz. Its purpose is to generate structured light for a real-time photogrammetry stereo vision setup. As conventional digital light projector (DLP) projection setups are limited in their maximum projection rate to 250Hz for gray-value patterns, stripe projection systems are usually applied for real-time three-dimensional (3D) measurements. However, these techniques can only be used on steady surfaces as phase unwrapping has to be done. In contrast, the proposed setup is able to measure the shape of multiple spatially separated objects at once. We compare the speckle setup with a system using a DLP projector and with other fast 3D shape measurement setups, like the widely used stripe projection methods, qualitatively and quantitatively.

Superfast multifrequency phase-shifting technique with optimal pulse width modulation

“…At current stage, we believe our measurement accuracy is not as high as other high-speed 3D shape measurement techniques such as the one described in Ref. [13]. Figure 3(a) shows the image after averaging three fringe patterns with the shortest wavelength.…”

Enhancement of Stereo Imagery by Artificial Texture Projection Generated Using a Lidar

“…Speckle is easily generated using either an optical fibre or a ground glass diffuser which allows for cheap and compact systems (Schaffer et al, 2010). Figure 3 shows an example of such a pattern.…”

A multi-view stereo based 3D hand-held scanning system using visual-inertial navigation and structured light

“…The contact measurement lacks due to its characteristic of touching object, slow performance and high cost of employing mechanically calibrated passive arms [1,5].The non-contact measurement is further divided into two kinds of optical techniques for 3D reconstruction i.e., active and passive techniques [2]. Passive technique constitutes the scene imaged by digital cameras from two or more viewpoints and poses correspondence problem due to the absence of strong texture on the surface of 3D object [3].To cope with this problem, active technique based on structured light was employed to create artificial texture on the surface of 3D objects [4]. 3D sensing systems based on structured light may be categorized into two types, camera-projector system and stereo camera with non-calibrated projector [5,6].The comparison of passive stereo, camera projector system and stereo camera with non-calibrated projector was described in [6].Structured light techniques can also be classified into sequential (multiple-shot) or single shot techniques and single shot technique is commonly employed for the moving 3D object with stringent constraint on the acquisition time [7].…”