Search results for "ndc"
showing 10 items of 1025 documents
Short baseline line matching for central imaging systems
2012
We develop a generic line matching method especially applicable to omnidirectional images taken from constructed scenes with short baseline motion where the motion of the imaging system between two views is mainly an arbitrary rotation and the translation of the camera between two views with respect to its distance to the imaged scene is negligible. We start by studying the relationship between images of lines on unitary sphere followed by proposing a simple algorithm for simultaneously matching vanishing points and lines. The developed algorithm is very simple, yet it works on images captured by all types of central imaging systems, including perspective, fish-eye and catadioptric images. …
Towards a real-time 3D shape reconstruction using a structured light system
2005
This paper deals with 3D shape reconstruction using a structured light system (SLS) which projects a matrix of laser rays onto the scene to be analyzed. The intrinsic problem of such a system is the correspondence problem solving, which in this particular case amounts to matching up the imaged spots and the originating laser rays. In this paper, we propose a method for automatically obtaining configurations of the system (COS) (i.e. the relative positions of the camera, laser projector, and measuring scene) that permit to achieve a direct and unambiguous correspondence. After, we propose a splitting cell algorithm, which efficiently performs a real-time correspondence procedure. Experimenta…
Which Is Which? Evaluation of Local Descriptors for Image Matching in Real-World Scenarios
2019
Matching with local image descriptors is a fundamental task in many computer vision applications. This paper describes the WISW contest held within the framework of the CAIP 2019 conference, aimed at benchmarking recent descriptors in challenging planar and non-planar real image matching scenarios. According to the contest results, the descriptors submitted to the competition, most of which based on deep learning, perform significantly better than the current state-of-the-art in image matching. Nonetheless, there is still room for improvement, especially in the case of non-planar scenes.
Stereo Matching Tecniques for Cloud-top Height Retrieval
2006
This paper presents an ongoing study for the estimation of the cloud-top height by using only geometrical methods. It is based on the hypothesis that an infra-red camera is on board a satellite and pairs of images concern nearly the same scene. Stereo-vision techniques are therefore explored in order to test the methodology for height retrieval and in particular results of several techniques of stereo matching are evaluated. This study includes area-based matching algorithms by implementing the basic versions, without considering any further steps of optimisation to improve the results. Dense depth maps are the final outputs whose reliability is verified by computing error statistics with r…
GRASP & evolutionary path relinking for medical image registration based on point matching
2010
Image registration is a very active research area in computer vision. Image registration methods, aim to find a transformation between two images taken under different conditions. Point matching is an image registration approach based on searching for the right pairing of points between the two images. From this matching, the registration transformation can be inferred by means of numerical methods. In this paper, we tackle the medical image registration problem adapting a new advanced hybrid metaheuristic composed by the GRASP and the evolutionary path relinking algorithms, called G&EvPR. The experiments conducted in this work have shown the good performance of G&EvPR compared to similar a…
Detecting multiple copies in tampered images
2010
Copy-move forgeries are parts of the image that are duplicated elsewhere into the same image, often after being modified by geometrical transformations. In this paper we present a method to detect these image alterations, using a SIFT-based approach. First we describe a state of the art SIFT-point matching method, which inspired our algorithm, then we compare it with our SIFT-based approach, which consists of three parts: keypoint clustering, cluster matching, and texture analysis. The goal is to find copies of the same object, i.e. clusters of points, rather than points that match. Cluster matching proves to give better results than single point matching, since it returns a complete and co…
MATERIALS AND PROCESSING ISSUES FOR THE MANUFACTURING OF INTEGRATED PASSIVE AND ACTIVE DEVICES ON FLEXIBLE SUBSTRATES
2008
Plast_ICs is a Public/Private Laboratory funded by Italian Government aimed to build a novel technological platform for the development of flexible electronics, mainly, but not solely, based on thin inorganic films. Integration of different functions, on single and/or multiple plastic foils, to generate a smart system is the final goal of the project. The building blocks of the platform will be presented, starting from the different plastic substrates characterization, going through the development of active devices, such as thin-film- transistors, and passive devices, like thin-film- resistors, capacitors, inductors. Fully inorganic elementary devices, based on optical patterning and in va…
Fast Axial-Scanning Widefield Microscopy With Constant Magnification and Resolution
2015
In this paper, we propose the use of electrically-addressable lens devices for performing fast non-mechanical axial scanning when imaging three-dimensional samples. This non-mechanical method can be implemented in any commercial microscope. The approach is based on the insertion of the tunable lens at the aperture stop of the microscope objective. By tuning the voltage, a stack of depth images of 3D specimens can be captured in real time and with constant magnification and resolution. The main advantage of our technique is the possibility of performing fast axial scanning free of mechanical vibrations.
FERROELECTRIC LIQUID CRYSTAL GLASSES FOR AMBLYOPIA RESEARCH
2008
ABSTRACT Ferroelectric Liquid Crystal (FLC) filters offer the speed of electronic light shutters and the vibration free operation. These characteristics make them ideal for applications requiring short exposure times and minimal blur, offering switching times of 0.0002 of a second. FLC filters can be used as the optical shutters for machine vision purposes, also in vision research. On the basis of FLC filters we have developed ferroelectric glasses, allowing temporal separation of optical information for both eyes. In the case of amblyopia (“lazy eye”) the only way to oblige the “lazy” eye to work is to close the other better-seeing eye. We advice an appliance for dynamic visual system trai…
An automated procedure for computing the packing properties of dense and locked sands by image analysis of thin sections
2014
The macroscopic mechanical behaviour of dense sands originates to a great extent from their microstructural characteristics such as the coordination number, the grain contact and the packing density indexes. The study of intergranular contacts and the reckoning of these indexes may be carried out on planar images of the grains either by means of time-consuming visual inspection assisted by CAD or by automatic image analysis. An innovative method for the automatic determination of microstructural characteristics of sands based on image analysis of thin section is proposed. Tests performed on a locked sand show that the proposed method is much more effective, convenient and faster than the us…