We present the Frequency Shift Method, a new structured light technique allowing 3D shape acquisition in the presence of strong interreflections. The intensity signal of each camera pixel is represented by one or several peaks in the Fourier domain. If there is no interreflection, only a single peak appears, otherwise several peaks are present. Each peak represents a projector pixel participating in the illumination of the surface point imaged at the camera pixel. In the baseline version of the proposed approach, the number of patterns required is proportional to the number of projector pixels. We also propose a modification that significantly reduces the required number of patterns by subdividing and encoding the projector into multiple virtual low-resolution projectors. A method based on dynamic programming is used to separate direct and indirect illuminations. Our experimental results illustrate the effectiveness of our method compared to existing ones.

Phase-shift profilometry (PSP) is a technique for acquiring non-contact three-dimensional measurements using a projector and a camera. The technique can be used to measure 3D surfaces with high accuracy. However, it can be sensitive to motion because phase images are sequentially captured. We propose a new technique that uses residual phase errors to minimize the influence of motion on the recovered phases (and 3D points). The method minimizes residual phase error with respect to apparent phase offset variations caused by motion. Furthermore, a total variation scheme is used to minimize spatial variations of apparent phase offset variations. We demonstrate the method with different moving objects, and we also study the effect of the magnitude of the motion on the accuracy of the recovered phases. Visual artefacts as well as accuracy loss associated with motion are found to be significantly decreased.

This paper proposes a hybrid software-hardware high-resolution projection system for 3D imaging based on fringe projection. The proposed solution combines the advantages of a digital projection with those of an analogue one. It is programmable and allows a high projection rate by avoiding mechanical displacements in the projection system. Moreover, it does not suffer from the limitations of digital systems such as the presence of inter-pixel gaps and limited resolution. The proposed projection system is relatively inexpensive to build since it is composed of a simple arrangement off-the-shelf components. The system is a combination of a low-resolution digital device such as a DMD, LCoS or LCD, some optical components and software to generate the fringe patterns. A prototype of a 3D scanner based on the proposed projection system is used to asses the fitness of the proposed technology.

This paper proposes a novel and efficient representation of the point-spread function (PSF) well suited for structured light systems used in digital profilometry. For this particular application the PSF is spatially variant over the working volume and the current parametric as well as non-parametric representations are insufficient. We validate our method using a standard data set and imagery acquired using an off-the-shelf multimedia projector and an industrial camera.

This paper describes an environment to automatically or semi-automatically compute the precise mapping between a set of 2D images and a triangulated 3D model built from high-resolution 3D range data. This environment is part of our Atelier3D framework for the modeling, visualization and analysis of large sensor-based datasets. This work was done to initially support three cultural heritage application projects: the modeling of the Grotta dei Cervi in Italy, of the Erechtheion in Athens, Greece, and of Leonardo's Mona Lisa. The proposed method combines image-based registration, feature matching, robust estimation techniques and advanced multi-resolution rendering with a powerful user interface.

This paper presents a new technique for fast, view-dependent, real-time visualization of large multiresolution geometric models with color or texture information. This method uses geomorphing to smoothly interpolate between geometric patches composing a hierarchical level-of-detail structure, and to maintain seamless continuity between neighboring patches of the model. It combines the advantages of view-dependent rendering with numerous additional features: the high performance rendering associated with static preoptimized geometry, the capability to display at both low and high resolution with minimal artefacts, and a low CPU usage since all the geomorphing is done on the GPU. Furthermore, the hierarchical subdivision of the model into a tree structure can be accomplished according to any spatial or topological criteria. This property is particularly useful in dealing with models with high resolution textures derived from digital photographs. Results are presented for both highly tesselated models (372 million triangles), and for models which also contain large quantities of texture (200 million triangles + 20 GB of compressed texture). The method also incorporates asynchronous out-of-core model management. Performances obtained on commodity hardware are in the range of 50 million geomorphed triangles/second for a benchmark model such as Stanford's St. Matthew dataset.

We present a new method for the stereoscopic display of complex virtual environments using a foveated arrangement of four images. The system runs on four rendering nodes and four projectors, for the fovea and periphery in each eye view. The use of high-resolution insets in a foveated configuration is well known. However, its extension to projector-based stereoscopic displays raises a specific issue: the visible boundary between fovea and periphery present in each eye creates a stereoscopic cue that may conflict with the perceived depth of the underlying scene. A previous solution to this problem displaces the boundary in the images to ensure that it is always positioned over stereoscopically corresponding scene locations. The new method proposed here addresses the same problem, but by relaxing the stereo matching criteria and reformulating the problem as one of spatial partitioning, all computations are performed locally on each node, and require a small and fixed amount of post-rendering processing, independent of scene complexity. We discuss this solution and present an OpenGL implementation; we also discuss acceleration techniques using culling and fragments, and illustrate the use of the method on a complex 3D textured model of a Byzantine crypt built using laser range imaging and digital photography.

The image of an opaque object is created by observing the reflection of the light incident on its surface. The dichromatic reflection model describes the surface reflection as the sum of two components, diffuse and specular terms. The specular reflection component is usually strong in its intensity and polarized significantly compared to the diffuse components. On the other hand, the intensity of the diffuse component is weak and it tends to be unpolarized except near occluding contours. Thus, the observation of an object through a rotating polarizer approximately yields images containing constant diffuse component and specular component of different intensity. In this paper, we show that diffuse and specular components of surface reflection can be separated as two independent components when we apply Independent Component Analysis to the images observed through a polarizer of different orientations. We give a separation simulation of artificial data and also give some separation results of real scenes.

No abstract available.

Abstract The National Research Council of Canada (NRC) has developed and patented three high‐resolution 3D imaging systems and processing algorithms which have been applied to a wide range of museum and heritage recording applications. The systems have been designed for different imaging applications and, in collaboration with a number of national and international museums and cultural agencies, have been used to scan a wide variety of objects and sites. The objective of this paper is to present a summary of the 3D technology and examples of its heritage applications. Copyright © 2003 John Wiley & Sons, Ltd.

Discusses the progress and the evolution of the development of range sensing techniques at the NRC laboratories. Essentially a 3D imaging project at the beginning, it has evolved to a new media project which requires the development of new tools for 3D modeling, editing, database searching and visualization. Generic applications related to documentation, inspection, target tracking and visual communication will be discussed.

This paper describes sensors and algorithms developed and used for the creation of coloured 3-D triangular meshes from a set of range images with registered colour measurements. The objective is the creation of a digital model of a real object that is compatible with established computer graphics techniques. Triangular meshes are the fundamental rendering primitive supported by most high performance graphics workstations. The surface colour of objects can be represented by attributing reflectance values to the vertices of the mesh. Such a geometric and reflectance model provides a uniform and general representation for sculptured surfaces with non-uniform colouring.

Introduces a new method for the calibration of a range camera based on active triangulation. The technique is based on a model derived from the geometry of the synchronized scanner. From known positions of a calibration bar, a logistic equation is fitted with values of spot positions read from a linear position detector at a number of angular positions of a scanning mirror. Furthermore, with an approximate form of the general equations describing the geometry, a series of design guidelines are derived to help a designer conduct a preliminary study of a particular range camera. Experimental results demonstrating the technique are found to compare favorably with theoretical predictions.>

A system for simultaneously measuring the 3-D shape and color properties of objects is described. Range data are obtained by triangulation over large volumes of the scene, whereas color components are separated by means of a white laser. Details are given concerning the modeling and the calibration of the system for bidirectional reflectance-distribution functions measurements. A reflection model is used to interpret the data collected with the system in terms of the underlying physical properties of the target. These properties are the diffuse reflectance of the body material, the Fresnel reflectance of the air media interface, and the slope surface roughness of the interface. Experimental results are presented for the extraction of these parameters. By allowing the subtraction of highlights from color images and the compensation for surface orientation, spectral reflectance modeling can help to understand 3-D scenes. A practical example is given where a color and range image is processed to yield uniform regions according to material pigmentation.>