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152
A Rendering Algorithm for Discrete Volume Density Objects
, 1993
"... : We present a new algorithm for simulating the effect of light travelling through volume objects. Such objects (haze, fog, clouds...) are usually modelized by voxel grids which define their density distribution in a discrete tridimensional space. The method we propose is a twopass MonteCarlo ray ..."
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Cited by 59 (1 self)
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: We present a new algorithm for simulating the effect of light travelling through volume objects. Such objects (haze, fog, clouds...) are usually modelized by voxel grids which define their density distribution in a discrete tridimensional space. The method we propose is a twopass MonteCarlo raytracing algorithm that does not make any restrictive assumptions neither about the characteristics of the objects (both arbitrary density distributions and phase functions are allowed) nor about the physical phenomena included in the rendering process (multiple scattering is accounted for). The driving idea of the algorithm is to use the phase function for MonteCarlo sampling, in order to modify the direction of the ray during scattering. Keywords : MonteCarlo RayTracing, Participating Media, Volume Density Objects, Multiple Scattering. 1 Introduction Rendering methods of objects defined by their density distribution in a tridimensional space can be divided in viewdependent and viewi...
Scaling Of `landscapes' In Landscape Ecology, Or, Landscape Ecology From A Beetle's Perspective
, 1989
"... Research performed on microlandscapes embodies the essence of landscape ecology by focusing on the logical consequences of the mosaic structure of different landscape elements. As an illustration, observations and simulations were used to test whether the fractal structure of grassland microlandsca ..."
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Cited by 36 (1 self)
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Research performed on microlandscapes embodies the essence of landscape ecology by focusing on the logical consequences of the mosaic structure of different landscape elements. As an illustration, observations and simulations were used to test whether the fractal structure of grassland microlandscapes affected the movement patterns of tenebrionid beeetles in natural environments. The significant tendency of beetles to avoid 1 cells with fractal dimensions of 1.85 to 1.89 (indicating the areafilling tendency of bare ground) demonstrated the role of landscape structure as a modifier of beetle movements or diffusion in heterogeneous landscapes. Experiments in microlandscapes may accelerate the development of quantitative conceptual frameworks applicable to landscapes at all scales.
Image Coding By Block Prediction Of Multiresolution Subimages
 IEEE Transactions on Image Processing
"... The redundancy of the multiresolution representation has been clearly demonstrated in the case of fractal images, but it has not been fully recognized and exploited for general images. Recently, fractal block coders have exploited the selfsimilarity among blocks in images. In this work we devise ..."
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Cited by 35 (2 self)
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The redundancy of the multiresolution representation has been clearly demonstrated in the case of fractal images, but it has not been fully recognized and exploited for general images. Recently, fractal block coders have exploited the selfsimilarity among blocks in images. In this work we devise an image coder in which the causal similarity among blocks of different subbands in a multiresolution decomposition of the image is exploited. In a pyramid subband decomposition, the image is decomposed into a set of subbands which are localized in scale, orientation and space. The proposed coding scheme consists of predicting blocks in one subimage from blocks in lower resolution subbands with the same orientation. Although our prediction maps are of the same kind of those used in fractal block coders, which are based on an iterative mapping scheme, our coding technique does not impose any contractivity constraint on the block maps. This makes the decoding procedure very simple and...
Fractal Approaches for Visualizing Huge Hierarchies
 In Proceedings of the 1993 IEEE Symposium on Visual Languages
, 1993
"... This paper describes fractal approaches to the problems which associate with visualizing huge hierarchies. The geometrical characteristic of a fractal, selfsimilarity, allows users to visually interact with a huge tree in the same manner at every level of the tree. The fractal dimension, a measure o ..."
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Cited by 31 (1 self)
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This paper describes fractal approaches to the problems which associate with visualizing huge hierarchies. The geometrical characteristic of a fractal, selfsimilarity, allows users to visually interact with a huge tree in the same manner at every level of the tree. The fractal dimension, a measure of complexity, makes it possible to control the total amount of displayed nodes. A prototype visualization system for UNIX directories is also shown. 1 Introduction Visualization systems for hierarchical structures, especially for huge 1 data structures, have a potential usefulness. For example, the visualization of whole UNIX directories might help system administrators to maintain the file systems. Since administrators could recognize, through the visualization, local file systems of each computer and remote file systems mounted by using NFS (Network File System), they might avoid mistakes, such as deleting or moving files which are being referenced by other computers. It is, however, m...
Provenance of correlations in psychological data
 PSYCHONOMIC BULLETIN & REVIEW
, 2005
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TwoDimensional Simulation of Gaseous Phenomena Using Vortex Particles
 In Proceedings of the 6th Eurographics Workshop on Computer Animation and Simulation
, 1995
"... This article presents a simple, fast and stable method for the animation and visualisation of turbulent gaseous fluids in two dimensions. We draw on well known methods from computational fluid dynamics to model the fluid using vorticity and velocity fields. While the vorticity is transported by a ..."
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Cited by 26 (1 self)
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This article presents a simple, fast and stable method for the animation and visualisation of turbulent gaseous fluids in two dimensions. We draw on well known methods from computational fluid dynamics to model the fluid using vorticity and velocity fields. While the vorticity is transported by a particle system, we use a uniform grid to compute velocities and displacements for each particle. This mixed approach where free particles move on a fixed grid requires little computational power, making it suitable for computer animation. The method simulates the behaviour of fluids in situations where the contact between fluid masses with different velocities generates an intermediate mixing layer which can give rise to turbulence phenomena. Unlike previous algorithms, it is possible to generate quasiturbulent patterns, where large scale coherent vortex structures are still discernible in the flow.
A survey of computational approaches to threedimensional layout problems
 COMPUTER AIDED DESIGN
, 2002
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A Fractal Model of Mountains with Rivers
 IN PROCEEDINGS OF GRAPHICS INTERFACE '93
, 1993
"... This paper addresses the longstanding problem of generating fractal mountains with rivers, and presents a partial solution that incorporates a squigcurve model of a river's course into the midpointdisplacement model for mountains. The method is based on the observation that both models can b ..."
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Cited by 26 (0 self)
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This paper addresses the longstanding problem of generating fractal mountains with rivers, and presents a partial solution that incorporates a squigcurve model of a river's course into the midpointdisplacement model for mountains. The method is based on the observation that both models can be expressed by similar contextsensitive rewriting mechanisms. As a result, a mountain landscape with a river can be generated using a single integrated process.