Search results for " pattern"
showing 10 items of 2245 documents
Estimation de surface de Bézier à partir d'images de lumière structurée dans une optique de compression
2013
National audience; Compression of 3D datas has become a topic of increasing importance over the evolution of scanners. With evolution of technologies, the commercial scanners give more and more data points, which can lead to difficulties in transmission or storage. In most cases, the acquisition does not take into account the final use of the data. While in many cases, this would limit the number of points. In this paper, we propose an approach which simplifies the scatterplot for industrial purposes using Bezier surfaces.
Urinary Diversion: How Experts Divert
2014
To determine the rates of the available urinary diversion options for patients treated with radical cystectomy for bladder cancer in different settings (pioneering institutions, leading urologic oncology centers, and population based).Population-based data from the literature included all patients (n = 7608) treated in Sweden during the period 1964-2008, from Germany (n = 14,200) for the years 2008 and 2011, US patients (identified from National Inpatient Sample during 1998-2005, 35,370 patients and 2001-2008, 55,187 patients), and from Medicare (n = 22,600) for the years 1992, 1995, 1998, and 2001. After the International Consultation on Urologic Diseases-European Association of Urology In…
The S-kernel: A measure of symmetry of objects
2007
In this paper we introduce a new symmetry feature named ''symmetry kernel'' (SK) to support a measure of symmetry. Given any symmetry transform S, SK of a pattern P is the maximal included symmetric sub-set of P for all directions and shifts. We provide a first algorithm to exhibit this kernel where the centre of symmetry is assumed to be the centre of mass. Then we prove that, in any direction, the optimal axis corresponds to the maximal correlation of a pattern with its symmetric version. That leads to a second algorithm. The associated symmetry measure is a modified difference between the respective surfaces of a pattern and its kernel. A series of experiments supports the actual algorit…
New method for field studies on the parapatric distribution of sibling species
1999
Abstract Spatial segregation (parapatry) often occurs between closely related species. The distributions of the two species are sometimes defined with a small overlapping zone (called a `sympatric area') which generally shifts. Exclusion is necessary to explain the persistence and shift of such a spatial pattern. Field studies are carried out to identify the type of interaction that leads to the required exclusion. This is usually achieved by estimating competition and predation parameters to define the type of interaction strong enough to imply exclusion. But interaction parameters are estimated by quantitative methods which require prolonged observation (5–10 years). These estimations are…
Synthetic aperture superresolution with multiple off-axis holograms
2006
An optical setup to achieve superresolution in microscopy using holographic recording is presented. The technique is based on off-axis illumination of the object and a simple optical image processing stage after the imaging system for the interferometric recording process. The superresolution effect can be obtained either in one step by combining a spatial multiplexing process and an incoherent addition of different holograms or it can be implemented sequentially. Each hologram holds the information of each different frequency bandpass of the object spectrum. We have optically implemented the approach for a low-numerical-aperture commercial microscope objective. The system is simple and rob…
Urban monitoring using multi-temporal SAR and multi-spectral data
2006
In some key operational domains, the joint use of synthetic aperture radar (SAR) and multi-spectral sensors has shown to be a powerful tool for Earth observation. In this paper, we analyze the potentialities of combining interferometric SAR and multi-spectral data for urban area characterization and monitoring. This study is carried out following a standard multi-source processing chain. First, a pre-processing stage is performed taking into account the underlying physics, geometry, and statistical models for the data from each sensor. Second, two different methodologies, one for supervised and another for unsupervised approaches, are followed to obtain features that optimize the urban rela…
Holography and Superresolution
2013
The capability of improving the spatial resolution of imaging systems is usually known as superresolution. Some methods provide improve resolution by playing with the imaging part of the system and without modifying the optical parameters of the imaging lenses. And others act over the geometry, shape and size of sampling pixels in the detection array. The former strategy allows optical superresolution while the latter provide geometrical superresolution. In this contribution, we will review the state of the art in optical superresolution approaches understood as the possibility to overcome the limited resolving power of imaging systems beyond the bounds imposed by Abbe's diffraction theory.…
Combining Defocus and Photoconsistency for Depth Map Estimation in 3D Integral Imaging
2017
This paper presents the application of a depth estimation method for scenes acquired using a Synthetic Aperture Integral Imaging (SAII) technique. SAII is an autostereoscopic technique consisting of an array of cameras that acquires images from different perspectives. The depth estimation method combines a defocus and a correspondence measure. This approach obtains consistent results and shows noticeable improvement in the depth estimation as compared to a minimum variance minimisation strategy, also tested in our scenes. Further improvements are obtained for both methods when they are fed into a regularisation approach that takes into account the depth in the spatial neighbourhood of a pix…
Fuzzy Integral Imaging Camera Calibration for Real Scale 3D Reconstructions
2014
In this paper, we present a quantitative analysis of the error in the reconstruction of a 3D scene which has been captured with Synthetic Aperture Integral Imaging system. The 3D information is obtained from 2D images for which the camera parameters are unknown. The model used for calibrating the Integral Imaging camera setup is based on fuzzy systems. These systems provide the opportunity for modeling of conditions which are inherently imprecisely defined. We demonstrate that the error in the 3D reconstruction not only depends on the number of cameras, but also to their relative positions. Our model is applied to a set of images captured experimentally from a real object. A true-color real…
Surpassing digital holography limits by lensless object scanning holography.
2012
We present lensless object scanning holography (LOSH) as a fully lensless method, capable of improving image quality in reflective digital Fourier holography, by means of an extremely simplified experimental setup. LOSH is based on the recording and digital post-processing of a set of digital lensless holograms and results in a synthetic image with improved resolution, field of view (FOV), signal-to-noise ratio (SNR), and depth of field (DOF). The superresolution (SR) effect arises from the generation of a synthetic aperture (SA) based on the linear movement of the inspected object. The same scanning principle enlarges the object FOV. SNR enhancement is achieved by speckle suppression and c…