Vincent Nozick

Laser-plasma scanning 3D display for putting digital contents in free space

We present a novel 3D display that can show any 3D contents in free space using laser-plasma scanning in the air. The laser-plasma technology can generate a point illumination at an arbitrary position in the free space. By scanning the position of the illumination, we can display a set of point illuminations in the space, which realizes 3D display in the space. This 3D display has been already presented in Emerging Technology of SIGGRAPH2006, which is the basic platform of our 3D display project. In this presentation, we would like to introduce history of the development of the laser-plasma scanning 3D display, and then describe recent development of the 3D contents analysis and processing technology for realizing an innovative media presentation in a free 3D space. The one of recent development is performed to give preferred 3D contents data to the 3D display in a very flexible manner. This means that we have a platform to develop an interactive 3D contents presentation system using the 3D display, such as an interactive art presentation using the 3D display. We would also like to present the future plan of this 3D display research project.

Online multiple view computation for autostereoscopic display

This paper presents a new online Video-Based Rendering method that creates simultaneously multiple views at every new frame. Our system is especially designed for communication between mobile phones using autostereoscopic display and computers. The new views are computed from 4 webcams connected to a computer and are compressed in order to be transfered to the mobile phone. Thanks to GPU programming, our method provides up to 16 images of the scene in realtime. The use of both GPU and CPU makes our method work on only one consumer grade computer.

Real-time free viewpoint video from uncalibrated cameras using plane-sweep algorithm

In this paper, we present a new online video-based rendering (VBR) method that creates new views of a scene from uncalibrated cameras. Our method does not require information about the cameras intrinsic parameters. For obtaining a geometrical relation among the cameras, we use projective grid space (PGS) which is 3D space defined by epipolar geometry between two basis cameras. The other cameras are registered to the same 3D space by trifocal tensors between these basis cameras. We simultaneously reconstruct and render novel view using our proposed plane-sweep algorithm in PGS. To achieve real-time performance, we implemented the proposed algorithm in graphics processing unit (GPU). We succeed to create novel view images in real-time from uncalibrated cameras and the results show the efficiency of our proposed method.

Real-time free viewpoint from multiple moving cameras

In recent years, some Video-Based Rendering methods have advanced from off-line rendering to on-line rendering. However very few of them can handle moving cameras while recording. Moving cameras enable to follow an actor in a scene, come closer to get more details or just adjust the framing of the cameras. In this paper, we propose a new Video-Based Rendering method that creates new views of the scene in live from four moving webcams. These cameras are calibrated in real-time using multiple markers. Our method fully uses both CPU and GPU and hence requires only one consumer grade computer.

Image Noise and Digital Image Forensics

Noise is an intrinsic specificity of all forms of imaging, and can be found in various forms in all domains of digital imagery. This paper offers an overall review of digital image noise, from its causes and models to the degradations it suffers along the image acquisition pipeline. We show that by the end of the pipeline, the noise may have widely different characteristics compared to the raw image, and consider the consequences in forensic and counter-forensic imagery.

Colorimetric correction for stereoscopic camera arrays

Colorimetric correction is a necessary task to generate comfortable stereoscopic images. This correction is usually performed with a 3D lookup table that can correct images in real-time and can deal with the non-independence of the colour channels. In this paper, we present a method to compute such 3D lookup table with a non-linear process that minimizes the colorimetric properties of the images. This lookup table is represented by a polynomial basis to reduce the number of required parameters. We also describe some optimizations to speedup the processing time.

Generic initialization for motion capture from 3d shape

Real time and markerless motion capture is an active research area, due to applications in human-computer interactions, for example. A large part of the existing markerless motion capture methods require an initialization step, consisting in finding the initial position of the different limbs of the subject. In this paper, we propose a new method for interactive time initialization step, only based on morphological and topological information and which can be easily adapted to any kind of model (full human body or only hand, animals, for example).

A hybrid approach for computing products of high-dimensional geometric algebras

Geometric Algebra is considered as a very intuitive tool to deal with geometric problems and it appears to be increasingly efficient and useful to deal with computer graphics solutions. For example, the Conformal Geometric Algebra includes circles, spheres, planes and lines as algebraic objects, and intersections between these objects are also algebraic objects. More complex objects such as conics, quadric surfaces can also be expressed and be manipulated using an extension of the conformal Geometric Algebra. However due to high dimension of their representations in Geometric Algebra, implementations of Geometric Algebra that are currently available do not allow efficient realizations of these objects. This paper presents a Geometric Algebra implementation dedicated for both low and high dimensions. The proposed method is a hybrid solution for precomputed code with fast execution and runtime computations with low memory requirement. More specifically, the proposed method combines a precomputed table approach with a recursive method using binary trees. Some rules are defined to select the most appropriate choice, according to the dimension of the algebra and the type of multivectors involved in the product. The resulting implementation is well suited for high dimensional spaces (e.g. algebra of dimension 15) as well as for lower dimensional space. This paper details the integration of this hybrid method as a plug-in into Gaalop, which is a very advanced optimizing code generator. This paper also presents some benchmarks to show the performances of our method, especially in high dimensional spaces.

Real-time scene reconstruction and triangle mesh generation using multiple RGB-D cameras

We present a novel 3D reconstruction system that can generate a stable triangle mesh using data from multiple RGB-D sensors in real time for dynamic scenes. The first part of the system uses moving least squares (MLS) point set surfaces to smooth and filter point clouds acquired from RGB-D sensors. The second part of the system generates triangle meshes from point clouds. The whole pipeline is executed on the GPU and is tailored to scale linearly with the size of the input data. Our contributions include changes to the MLS method for improving meshing, a fast triangle mesh generation method and GPU implementations of all parts of the pipeline.

Camera array image rectification and calibration for stereoscopic and autostereoscopic displays

This paper presents an image rectification method for an arbitrary number of views with aligned camera center. This paper also describes how to extend this method to easily perform a robust camera calibration. These two techniques can be used for stereoscopic rendering to enhance the perception comfort or for depth from stereo. In this paper, we first expose why epipolar geometry is not suited to solve this problem. Second, we propose a nonlinear method that includes all the images in the rectification process. Then, we detail how to extract the rectification parameters to provide a quasi-Euclidean camera calibration. Our method only requires point correspondences between the views and can handle images with different resolutions. The tests show that it is robust to noise and to sparse point correspondences among the views.