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A shadow is a dark area where light from a light source is blocked by an object. It occupies all of the three-dimensional volume behind an object with light in front of it. The cross section of a shadow is a two-dimensional silhouette, or a reverse projection of the object blocking the light. Point and non-point light sources A point source of light casts only a simple shadow, called an "umbra". For a non-point or "extended" source of light, the shadow is divided into the umbra, penumbra, and antumbra. The wider the light source, the more blurred the shadow becomes. If two penumbras overlap, the shadows appear to attract and merge. This is known as the shadow blister effect. The outlines of the shadow zones can be found by tracing the rays of light emitted by the outermost regions of the extended light source. The umbra region does not receive any direct light from any part of the light source and is the darkest. A viewer located in the umbra region cannot directly see

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1ère année: bases nécessaires à la représentation informatique 2D (3D). Passage d'un à plusieurs logiciels: compétence de choisir les outils adéquats en 2D et en 3D. Mise en relation des outils de CAO et DIM: regard critique et aptitude à choisir les méthodes nécessaires au résultat recherché.

The students study and apply fundamental concepts and algorithms of computer graphics for rendering, geometry synthesis, and animation. They design and implement their own interactive graphics programs.

Ce cours a pour objectif de familiariser les étudiants avec les principaux concepts, instruments et techniques de la télédétection environnementale. Les interactions ondes/matière, les différents types instruments et les techniques de traitements d'images sont abordés.

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The measurement of the position of single-sized spheres in 3D from a single, divergent, radiographic projection is addressed in the present study with the development of a novel method. Generally speaking, the location of the shadow cast by a single sphere on a detector defines a source-detector ray; the position of the particle along this ray is identified by the strong prior knowledge of its radius and the size of the shadow. For a dense assembly of equal-sized particles whose projections overlap, a novel Fourier transform based technique is introduced to give a first 3D determination of the particle centres. The uncertainty of this measurement is calculated from synthetic data with a known noise distribution. A further refinement of this measurement is performed based on the minimisation of the projection residual. The combined approach is validated both on synthetic data, and on real radiographs of a glass bead packing. The effect of noise on the measurement uncertainty is evaluated. The technique is made available to the community in the open source python package radioSphere.

2021

Nanostencil technique and its applications to Nanoelectronics

Jürgen Brugger, Oscar Vazquez Mena

The Nanostencil technique is an emerging nanopatterning method based on shadow mask evaporation. Micro and sub-micron apertures (down to 100-nm scale) are patterned in 100-500 nm thick low-stress silicon nitride membranes. The membrane is brought in close proximity to a substrate and metal is shadow evaporated through the apertures on to a desired substrate. This technique has been successfully applied on full range-wafers, with micro- and nano-apertures in the same device. In this presentation we will give an introduction to the technique, the latest improvements achieved by in LMIS and the potential applications for Nanoelectronics and CMOS technology.

2005

Pedestrian detection by range imaging

Heinz Hügli

Remote detection by camera offers a versatile means for recording people activities. Relying principally on changes in video images, the method tends to fail in presence of shadows and illumination changes. This paper explores a possible remedy to these problems by using range cameras instead of conventional video cameras. As range is an intrinsic measure of object geometry, it is basically not affected by illumination. The study described in this paper considers range detection by two state-of-the art cameras, namely a stereo and a time-of-flight camera. Performed investigations consider typical situations of pedestrian detection. The presented results are analyzed and compared in performance with conventional results. The study shows the effective potential of range camera to get rid of light change problems like shadow effects but also presents some current limitations of range cameras.

2007

Rayleigh scattering

Rayleigh scattering (ˈreɪli ), named after the 19th-century British physicist Lord Rayleigh (John William Strutt), is the predominantly elastic scattering of light or other electromagnetic radiation

Solar eclipse

A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby obscuring the view of the Sun from a small part of the Earth, totally or partially. Such an alignment occurs approximat