Classification of Illumination Methods for Mixed Reality

A mixed reality (MR) represents an environment composed both by real and virtual objects. MR applications are used more and more, for instance in surgery, architecture, cultural heritage, entertainment, etc. For some of these applications it is important to merge the real and virtual elements using consistent illumination. This paper proposes a classification of illumination methods for MR applications that aim at generating a merged environment in which illumination and shadows are consistent. Three different illumination methods can be identified: common illumination, relighting and methods based on inverse illumination. In this paper a classification of the illumination methods for MR is given based on their input requirements: the amount of geometry and radiance known of the real environment. This led us to define four categories of methods that vary depending on the type of geometric model used for representing the real scene, and the sdifferent radiance information available for each point of the real scene. Various methods are described within their category. The classification points out that in general the quality of the illumination interactions increases with the amount of input information available. On the other hand, the accessibility of the method decreases since its pre‐processing time increases to gather the extra information. Recent developed techniques managed to compensate unknown data with clever techniques using an iterative algorithm, hardware illumination or recent progress in stereovision. Finally, a review of illumination techniques for MR is given with a discussion on important properties such as the possibility of interactivity or the amount of complexity in the simulated illumination.     

Evolution of the aroma composition of wines supplemented with grape flavour precursors from different varietals during accelerated wine ageing

The wines obtained by fermentation of a model medium supplemented with flavour precursors from different grape varieties (Muscat, Chardonnay, Grenache, Tempranillo, Merlot, Cabernet Sauvignon, Verdejo, and Syrah) were submitted to an accelerated ageing at 50 °C for 9 weeks simulating maturation in the bottle. The volatile compounds coming from grape flavour precursors were extracted by SPE and determined by GC–MS at the end of the alcoholic fermentation and after 1, 3, and 9 weeks of ageing. In general, the biggest changes were observed in the first week of accelerated ageing, most compounds showing a significant increase and a further steady decrease in their concentrations. Unexpectedly, Riesling acetal, 1,1,6-trimethyl-1,2-dihydronaphthalene (TDN), and trans-1-(2,3,6-trimethylphenyl)buta-1,3-diene (TPB) also followed this trend. However, vanillin derivatives, furan linalool oxides, 3-oxo-β-ionone, actinidols, 4-ethylphenol, and guaiacol showed a continuous increase during the ageing process. Syrah and Muscat were the most different varieties after fermentation and also at the end of the process. Differences between the rest of the varieties increased during the accelerated ageing, and, in most cases, differences were in accordance with those observed after acid and enzymatic hydrolysis of the grape precursor extracts.     

Image-based crowd rendering

Populated virtual urban environments are important in many applications, from urban planning to entertainment. At the current stage of technology, users can interactively navigate through complex, polygon-based scenes rendered with sophisticated lighting effects and high-quality antialiasing techniques. As a result, animated characters (or agents) that users can interact with are also becoming increasingly common. However, rendering crowded scenes with thousands of different animated virtual people in real time is still challenging. To address this, we developed an image-based rendering approach for displaying multiple avatars. We take advantage of the properties of the urban environment and the way a viewer and the avatars move within it to produce fast rendering, based on positional and directional discretization. To display many different individual people at interactive frame rates, we combined texture compression with multipass rendering     

Coherent radiance capture of scenes under changing illumination conditions for relighting applications

Relighting algorithms make it possible to take a model of a real-world scene and virtually modify its lighting. Unlike other methods that require controlled conditions, we introduce a new radiance capture method that allows the user to capture parts of the scene under different lighting conditions. A novel calibration method is presented that finds the positions of reflective spheres and their mathematically accurate projection onto the scene geometry. The resulting radiance distribution is used to estimate a diffuse reflectance for each object, computed coherently using the appropriate light probe image. Finally, the scene is relit using a novel illumination pattern.     

Interactive High-Quality Soft Shadows in Scenes with Moving Objects

Interactive rendering of soft shadows (or penumbra) in scenes with moving objects is a challenging problem. High quality walkthrough rendering of static scenes with penumbra can be achieved using pre-calculated discontinuity meshes, which provide a triangulation well adapted to penumbral boundaries, and backprojections which provide exact illumination computation at vertices very efficiently. However, recomputation of the complete mesh and back-projection structures at each frame is prohibitively expensive in environments with changing geometry. This recomputation would in any case be wasteful: only a limited part of these structures actually needs to be recalculated. We present a novel algorithm which uses spatial coherence of movement as well as the rich visibility information existing in the discontinuity mesh to avoid unnecessary recomputation after object motion. In particular we isolate all modifications required for the update of the discontinuity mesh by using an augmented spatial subdivision structure and we restrict intersections of discontinuity surfaces with the scene. In addition, we develop an algorithm which identifies visibility changes by exploiting information contained in the planar discontinuity mesh of each scene polygon, obviating the need for many expensive searches in 3D space. A full implementation of the algorithm is presented, which allows interactive updates of high-quality soft shadows for scenes of moderate complexity. The algorithm can also be directly applied to global illumination.     

Reactive extraction of acylglycerides using <Emphasis Type="Italic">Aspergillus flavus</Emphasis> resting cells

A one-pot TAG extraction and FAME formation using fungal resting cells and oilseeds at moderate temperature are described. The final yield of methyl esters is increased by the sequential addition of water and methanol. The process can be carried out either with solvents or in a solvent-free system. When a solvent-free medium is used, the final yield will increase if soft oilseeds are used.     

Automatic high-dynamic range image generation for dynamic scenes.

Automatic high-dynamic range image generation from low-dynamic range images offers a solution to conventional methods, which require a static scene. The method consists of two modules: a camera-alignment module and a movement detector, which removes the ghosting effects in the HDRI created by moving objects.