Marc Rioux

Bio: Marc Rioux is an academic researcher from National Research Council. The author has contributed to research in topics: Laser scanning & Image processing. The author has an hindex of 34, co-authored 120 publications receiving 5144 citations.

Laser ranging: a critical review of usual techniques for distance measurement

Abstract: We review some usual laser range finding techniques for in- dustrial applications. After outlining the basic principles of triangulation and time of flight (pulsed, phase-shift and frequency modulated continu- ous wave (FMCW)), we discuss their respective fundamental limitations. Selected examples of traditional and new applications are also briefly presented. © 2001 Society of Photo-Optical Instrumentation Engineers.

Laser range finder based on synchronized scanners

Abstract: A new geometrical arrangement is proposed to improve performances of optical triangulation Two scanners in synchronization allow a linear position sensor to be used for surface topography measurement Besides a large increase in speed of measurement (approximately megahertz), the new geometry allows considerable reduction of the optical head size compared with usual geometries, so the shadow effects are reduced proportionally It also provides a means to obtain a very large field of view without compromising on resolution Geometrical analysis and experimental results are presented

Description of shape information for 2-D and 3-D objects

Abstract: The description of the spatial characteristics of two- and three-dimensional objects, in the framework of MPEG-7, is considered. The shape of an object is one of its fundamental properties, and this paper describes an efficient way to represent the coarse shape, scale and composition properties of an object. This representation is invariant to resolution, translation and rotation, and may be used for both two-dimensional (2-D) and three-dimensional (3-D) objects. This coarse shape descriptor will be included in the eXperimentation Model (XM) of MPEG-7. Applications of such a description to search object databases, in particular the CAESAR anthropometric database are discussed.

Three-dimensional registration using range and intensity information

Abstract: The determination of relative pose between two range images, also called registration, is a ubiquitous problem in computer vision, for geometric model building as well as dimensional inspection. The method presented in this paper takes advantage of the ability of many active optical range sensors to record intensity or even color in addition to the range information. This information is used to improve the registration procedure by constraining potential matches between pairs of points based on a similarity measure derived from the intensity information. One difficulty in using the intensity information is its dependence on the measuring conditions such as distance and orientation. The intensity or color information must first be converted into a viewpoint-independent feature. This can be achieved by inverting an illumination model, by differential feature measurements or by simple clustering. Following that step, a robust iterative closest point method is then used to perform the pose determination. Using the intensity can help to speed up convergence or, in cases of remaining degrees of freedom (e.g. on images of a sphere), to additionally constrain the match. The paper will describe the algorithmic framework and provide examples using range-and-color images.

Ring pattern of a lens-axicon doublet illuminated by a Gaussian beam

Abstract: An axicon and a lens are combined to form an optical system producing a ring-shaped pattern. The purpose of this paper is to show that when a lens-axicon combination is illuminated by a Gaussian beam, the transverse distribution of the focal ring is also a Gaussian distribution. The typical width of this distribution was found to be, in the case of the lens-axicon combination, 1.65 times greater than the typical width of the Gaussian beam obtained by focusing the same beam using the lens alone. This focusing system is well suited for the drilling of good quality large diameter holes using a high power laser beam.

Efficient variants of the ICP algorithm

Abstract: The ICP (Iterative Closest Point) algorithm is widely used for geometric alignment of three-dimensional models when an initial estimate of the relative pose is known. Many variants of ICP have been proposed, affecting all phases of the algorithm from the selection and matching of points to the minimization strategy. We enumerate and classify many of these variants, and evaluate their effect on the speed with which the correct alignment is reached. In order to improve convergence for nearly-flat meshes with small features, such as inscribed surfaces, we introduce a new variant based on uniform sampling of the space of normals. We conclude by proposing a combination of ICP variants optimized for high speed. We demonstrate an implementation that is able to align two range images in a few tens of milliseconds, assuming a good initial guess. This capability has potential application to real-time 3D model acquisition and model-based tracking.

Robot vision

Abstract: A scheme is developed for classifying the types of motion perceived by a humanlike robot. It is assumed that the robot receives visual images of the scene using a perspective system model. Equations, theorems, concepts, clues, etc., relating the objects, their positions, and their motion to their images on the focal plane are presented. >

The digital Michelangelo project: 3D scanning of large statues

Abstract: We describe a hardware and software system for digitizing the shape and color of large fragile objects under non-laboratory conditions Our system employs laser triangulation rangefinders, laser time-of-flight rangefinders, digital still cameras, and a suite of software for acquiring, aligning, merging, and viewing scanned data As a demonstration of this system, we digitized 10 statues by Michelangelo, including the well-known figure of David, two building interiors, and all 1,163 extant fragments of the Forma Urbis Romae, a giant marble map of ancient Rome Our largest single dataset is of the David - 2 billion polygons and 7,000 color images In this paper, we discuss the challenges we faced in building this system, the solutions we employed, and the lessons we learned We focus in particular on the unusual design of our laser triangulation scanner and on the algorithms and software we developed for handling very large scanned models

Lambertian reflectance and linear subspaces

Abstract: We prove that the set of all Lambertian reflectance functions (the mapping from surface normals to intensities) obtained with arbitrary distant light sources lies close to a 9D linear subspace. This implies that, in general, the set of images of a convex Lambertian object obtained under a wide variety of lighting conditions can be approximated accurately by a low-dimensional linear subspace, explaining prior empirical results. We also provide a simple analytic characterization of this linear space. We obtain these results by representing lighting using spherical harmonics and describing the effects of Lambertian materials as the analog of a convolution. These results allow us to construct algorithms for object recognition based on linear methods as well as algorithms that use convex optimization to enforce nonnegative lighting functions. We also show a simple way to enforce nonnegative lighting when the images of an object lie near a 4D linear space. We apply these algorithms to perform face recognition by finding the 3D model that best matches a 2D query image.