Colorful 3-D Imaging Using an Infrared Dammann Grating

3-D profilometry is one of the most important branches of measurement science and technology. In this paper, a new colorful 3-D imaging method using near-infrared (NIR) laser (850 nm) dot array generated by a Dammann grating is proposed. Two NIR cameras mounted with narrowband passed filters are adopted to capture laser patterns on objects. A color camera mounted with an infrared cutoff filter is adopted to capture color information. A simplified multiviews' matching method for dot array, which is the key of this 3-D imaging system, is proposed. A new geometric constraint named ray constraint is applied to multiview matching with the help of precalibration of laser dot array. Point clouds with color information are obtained according to triangulation. We used the experimental apparatus to scan a colorful plane with colorful attachments on it, and its colorful point clouds (about 56 000 sample points) were obtained. Experiments demonstrate that this apparatus achieves a depth accuracy of 0.21 mm at the measuring distance of 300 mm. This new colorful 3-D imaging has advantages of low cost, low power consumption, flexible structure, and portability, which should be highly interesting for practical applications.