Cities of Earth, Cities of Rubble

This chapter assesses the destroyed landscape of war and the cities of earth that soldiers built to survive, crafting a semi-urban space using standard issue spades and attempting to recreate aspects of civilian life. During the Great Patriotic War, survival at the front was virtually impossible without the help of an ancient hand tool: the spade. Indeed, the idea of the spade as a loyal friend became a major trope of military propaganda. That such a humble object received so much attention is telling. The spade was the key to soldiers' reading, shaping, and using the landscape. The soldier's small spade was an anonymous object, standard to everyone, and manuals taught soldiers to dig trenches according to a regular plan, yet Red Army soldiers excavated highly personalized spaces. Ultimately, the small, relatively primitive object and the labor it facilitated were central to the experience of millions of people in one of the most technologically advanced conflicts in world history.

(121514) 1999 UJ7: A primitive, slow-rotating Martian Trojan

Aims. The goal of this investigation is to determine the origin and surface composition of the asteroid (121514) 1999 UJ7, the only currently known L4 Martian Trojan asteroid. Methods. We have obtained visible reflectance spectra and photometry of 1999 UJ7 and compared the spectroscopic results with the spectra of a number of taxonomic classes and subclasses. A light curve was obtained and analysed to determine the asteroid spin state. Results. The visible spectrum of 1999 UJ7 exhibits a negative slope in the blue region and the presence of a wide and deep absorption feature centred around ~0.65 μm. The overall morphology of the spectrum seems to suggest a C-complex taxonomy. The photometric behaviour is fairly complex. The light curve shows a primary period of 1.936 d, but this is derived using only a subset of the photometric data. The asteroid may be in a non-principal axis rotational state, but our observational coverage is insufficient to draw definitive conclusions. Conclusions. Although the observed spectral absorption is wider and deeper, this finding may be compatible with the 0.7 μm spectral feature exhibited by some Ch-type asteroids and could possibly be interpreted as diagnostic of the presence of hydrated minerals. The inferred composition of 1999 UJ7 as a primitive object can be consistent with a volatile-rich object originally accreted beyond the snow line of the solar system, and subsequently evolved to reach the inner regions of the solar system.

3D Mosaic from Images

This paper presents a tool for 3D object mosaic. Given a set of background removed input images, we first compute a 3D reconstructed volumetric model body using shape from silhouette. The granularity of a volumetric body is the user input. Voxel center coordinates, voxel color, and surface normal of the voxel are computed for 3D mosaic. The voxels of reconstructed volumetric body are replaced by primitive shapes such as sphere, cylinder, cone, etc. We call this process as a 3D mosaic. The background-eliminated input images may contain information on body parts supplied by a user. Using information on body parts, only a part of 3D reconstructed volumetric body is replaced by a new shape while the rest of body retains voxel information. The surface normal values are used for primitive shapes with direction such as a cone. 3D mosaic can be used for emphasizing or deemphasizing a part of 3D reconstructed model body, similar to the function of a 2D image mosaic. Emphasizing and deemphasizing is done by resolution, surface normal, size of body parts, color and/or shape of the 3D primitive object.

Isoluminance Contours

This chapter introduces the Isoluminance Contour Model, which not only provides a quick and easy method for generating images, but also dramatically reduces the amount of work required by traditional computer graphics methods. It starts with the history of the model from its conception in 1981: it was used to generate flat-shaded greyscale, simple, primitive objects such as cubes, cylinders, cones, and spheres, by generating full-color smooth-shaded images for animated sequences. The model compares the degree of realism and the speed of production it generates with that achieved by using smooth shading and ray-tracing methods. It ultimately describes how the amount of data used by the Isoluminance Contour Model can be adapted dynamically to suit the screen size of the primitive object being generated, making real-time 4-dimensional animated visualization feasible on a Pentium 400 (or equivalent) or faster PC.

Ordinal and Probabilistic Representations of Acceptance

An accepted belief is a proposition considered likely enough by an agent, to be inferred from as if it were true. This paper bridges the gap between probabilistic and logical representations of accepted beliefs. To this end, natural properties of relations on propositions, describing relative strength of belief are augmented with some conditions ensuring that accepted beliefs form a deductively closed set. This requirement turns out to be very restrictive. In particular, it is shown that the sets of accepted belief of an agent can always be derived from a family of possibility rankings of states. An agent accepts a proposition in a given context if this proposition is considered more possible than its negation in this context, for all possibility rankings in the family. These results are closely connected to the non-monotonic 'preferential' inference system of Kraus, Lehmann and Magidor and the so-called plausibility functions of Friedman and Halpern. The extent to which probability theory is compatible with acceptance relations is laid bare. A solution to the lottery paradox, which is considered as a major impediment to the use of non-monotonic inference is proposed using a special kind of probabilities (called lexicographic, or big-stepped). The setting of acceptance relations also proposes another way of approaching the theory of belief change after the works of Gärdenfors and colleagues. Our view considers the acceptance relation as a primitive object from which belief sets are derived in various contexts.