ÐIn the ®elds related to geometric modelling, it is fundamental to count on robust. In this work we present a new algorithm for testing the intersection between a segment and a polygon in 3D space. This algorithm is robust and ecient, and it is the basis of most operations developed in geometric modelling. After, we will apply this algorithm to a classic problem in computer graphics: determini...

An experimental method for modelling and rendering liquids in motion is presented. A particle system is used to model dynamic liquid behaviour, while implicit surfaces serve as a wrapper to support realistic rendering methods. Aspects of particle-environment interaction and the use of dynamically sized particle primitives are discussed. Techniques used in the generation of implicit surfaces are...

A new gamma and X-Ray simulation module has been integrated to the CIVA software and completes the already available UT and ECT modules. This module is based on a combination of NDT radiographic modules developed at the CEA LETI and at EDF R&D. Direct radiation is calculated from an analytical approach (ray tracer and Beer-Lambert law for the attenuation) while the scattered radiation is simula...

introduction: monte carlo (mc) is the most common method for simulating virtual spect projections. it is useful for optimizing procedures, evaluating correction algorithms and more recently image reconstruction as a forward projector in iterative algorithms; however, the main drawback of mc is its long run time. we introduced a model based method considering the effect of body attenuation and i...

Progressive addition lenses are a relatively new approach to compensate for defects of the human visual system. While traditional spectacles use rotationally symmetric lenses, progressive lenses require the specification of freeform surfaces. This poses difficult problems for the optimal design and its visual evaluation. This paper presents two new techniques for the visualization of optical sy...

The synthesis of a pyridine-N-oxide containing rotaxane, not requiring an additional ionic template, has been achieved in 32% yield. Successful rotaxane formation is dependent upon the structure of the isophthalamide macrocycle used, an observation which has been rationalised by a combination of NMR spectroscopy, X-ray crystallography and computational modelling.

Fluorine interaction assisted AIEE characteristic in an expanded calixbenzophyrin is presented by single-crystal X-ray-diffraction analysis and molecular modelling approaches. Selective exposure to volatile organic compounds such as ketones and esters results in the breaking of fluorine interaction, leading to enhanced monomer emission.

We consider the problem of visualizing 3D objects deened as a Minkowski addition or subtraction of elementary objects. It is shown that such visualizations can be obtained by using techniques from computer graphics such as ray tracing and Constructive Solid Geometry. Applications of the method are found in solid modelling and shape description.

We incorporate a contribution to reionisation from X-rays within analytic and semi-numerical simulations of the 21-cm signal arising from neutral hydrogen during the epoch of reionisation. The relatively long X-ray mean free path (MFP) means that ionisations due to X-rays are not subject to the same density bias as UV ionisations, resulting in a substantive modification of the statistics of the...

The evidence for obscured AGN and in particular for obscured quasars is discussed. The spectrum and source modelling of the X-ray Background suggests that most massive black holes grow by obscured accretion. A possible major growth phase which is Compton thick is explored and shown to be difficult to detect directly with current instruments .