Search results for "computer vision"
showing 10 items of 2353 documents
An Efficient Method for the Visualization of Spectral Images Based on a Perception-Oriented Spectrum Segmentation
2010
We propose a new method for the visualization of spectral images. It involves a perception-based spectrum segmentation using an adaptable thresholding of the stretched CIE standard observer colormatching functions. This allows for an underlying removal of irrelevant channels, and, consequently, an alleviation of the computational burden of further processings. Principal Components Analysis is then used in each of the three segments to extract the Red, Green and Blue primaries for final visualization. A comparison framework using two different datasets shows the efficiency of the proposed method.
A combined single range and single image device for low-cost measurement of building facade features
2008
The dimensions of building facades and window apertures are usually determined by making direct measurements using tapes and plummets. This approach, however, has a number of drawbacks including the physical risk to which the persons making the measurements are exposed. This paper proposes an indirect approach based on close range photogrammetry that is inexpensive, simple, fast and safe, and which does not require specialist staff or direct ground control measurements. The method is based on taking a picture using a digital camera and measuring the distance to the object using a handheld laser distance meter. Both items of equipment are mounted on a specially designed support that allows t…
Combined Endo- and Exoscopic Semi-robotic Manipulator System for Image Guided Operations
2006
This paper describes the development of a robotic assistance system for image guided operations. To minimize operation time, a multimodal user interface enables freehand robotic manipulation of an extracorporeal stereoscopic digital camera (exoscope) and an endoscope. The surgeon thereby wears a head-mounted unit with a binocular display, a head tracker, a microphone and earphones. Different view positioning and adjustment modes can be selected by voice and controlled by head rotation while pressing a miniature confirmation button with a finger. Initial studies focused on the evaluation and optimization of the intuitiveness, comfort and precision of different modes of operation, including a…
<title>Stereoacuity determination at changing contrast of colored stereostimuli</title>
2003
Studies are focused on design and appraisal of an objective test for assessment of the stereovision quality in unfavorable conditions. Stereostimuli of different colors are used while the contrast of one of the stimulus being varied. Tests are based on principles of black-and-white and two primary color random dot stereotests. Experiments are divided by the method of stimuli display and separation: 1) stereoeffect is obtained haploscopically - by use of spectacles with color filters (blue and red) or prisms, 2) stimuli separation is obtained by liquid crystal shutters when both eye stimuli are demonstrated with a different delay. The stereovision threshold is determiend at different stimuli…
Characterization of a digital camera as an absolute tristimulus colorimeter
2003
An algorithm is proposed for the spectral and colorimetric characterization of digital still cameras (DSC) which allows them to be used as tele-colorimeters with CIE-XYZ color output, in cd/m2. The spectral characterization consists in the calculation of the color-matching functions from the previously measured spectral sensitivities. The colorimetric characterization consists in trans- forming the raw RGB digital data into absolute tristimulus values CIE-XYZ (in cd/m2) under variable and unknown spectroradiometric conditions. Thus, in the first stage, a gray balance was applied over the raw RGB digital data to convert them into RGB relative colorimetric values. In the second stage, an algo…
Robust technique for 3D shape reconstruction
2017
Abstract In this paper a robust and simple scheme is presented for three dimensional (3D) shape reconstruction of real object. A novel composite pattern technique is proposed for projecting the light pattern on the object of interest. The proposed scheme reduces the number of patterns by combining the primary color coded channels into one composite format. Our approach uses both spatial and temporal intensity variation for calibration and construction phase. Gamma calibration is considered with the propose scheme. High quality depth map is obtained from the linear light reflected by the shape of object without complex calculations. Experimental results demonstrated that proposed technique i…
Cartographic Language in Thematic Maps
2015
This paper analyzes the effectiveness of maps as transmitters of information. To this end, some basic concepts concerning the properties of cartographic language are examined, with the aim of helping the reader design maps conveying geographic information as clearly as possible. It also describes the innate taste of geographers for maps –how these attract and stimulate them. Then it deals with the emergence of the Internet and the new technologies allowing massive map visualization, downloading and production. The paper is illustrated with ten thematic maps, in which visual variables (i.e. size, shape, value, color, orientation and texture) are combined with the different marks (points, lin…
Measurement of three-dimensional mirror parameters by polarization imaging applied to catadioptric camera calibration
2008
International audience; We present a new efficient method for calibration of cata- dioptric sensors. The method is based on an accurate measurement of the three-dimensional parameters of the mirror through polariza- tion imaging. While inserting a rotating polarizer between the cam- era and the mirror, the system is automatically calibrated without any calibration patterns. Moreover, this method permits most of the constraints related to the calibration of catadioptric systems to be relaxed. We show that, contrary to our system, the traditional meth- ods of calibration are very sensitive to misalignment of the camera axis and the symmetry axis of the mirror. From the measurement of three-di…
Computer Vision Interaction for People with Severe Movement Restrictions
2006
In this paper we present the starting point of research in applying humancomputer interaction (HCI) techniques to help people with cerebral palsy to use computers via vision-based interaction. Our work includes the development and improvement of visionbased assistive technology, which was tested in experiments with cerebral palsy users. A brief review of current assistive technologies for severely physically impaired people and an explanation of the developed applications of such technologies are also presented. The final part of the paper describes the experimentation goals, process, and preliminary results. Future work directions are also indicated.