Predetermining visibility priority in 3-D scenes (Preliminary Report) (original) (raw)
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Visibility Preprocessing for Complex 3D Scenes Using Hardware-Visibility Queries
International Journal of Image and Graphics, 2006
In cases of densely occluded urban scenes, it is useful to determine the visibility of scenes, since only small parts of the scene are visible from a given cell. In this paper, we introduce a new visibility preprocessing method that efficiently computes potentially visible objects for volumetric cells. The proposed method deals with general 3D polygonal models and invisible objects jointly blocked by multiple occluders. The proposed approach decomposes volume visibility into a set of point visibilities, and then computes point visibility using hardware-visibility queries. We carry out experiments on various large-scale scenes, and show the performance of our algorithm. Our performance analysis approach estimates the exact solution of volume visibility. From differences between the estimated solution and the proposed algorithms solution, we show that our algorithm seeks a tight overestimate of the potentially visible set (PVS).
The 3D visibility complex : a new approach to the problems of accurate visibility
Eurographics, 1996
Visibility computations are central in any computer graphics application. The most common way to reduce this expense is the use of approximate approaches using spatial subdivision. More recently analytic approaches efficiently encoding visibility have appeared for 2D (the visibility complex) and for certain limited cases in 3D (aspect graph, discontinuity meshes). In this paper we propose a new way of describing and studying the visibility of 3D space by a dual space of the 3D lines, such that all the visibility events are described. A new data-structure is defined, called the 3D visibility complex, which encapsulates all visibility events. This structure is global and complete since it encodes all visibility relations in 3D, and is spatially coherent allowing efficient visibility queries such as view extraction, aspect graph, discontinuity mesh, or form factor computation. A construction algorithm and suitable data structures are sketched.
Visibility Computations for Real-Time Rendering in General 3D Environments
Sichtbarkeitsberechnungen sind essentielle Verfahren im Bereich der Computergrafik, notwendig für verschnellerte Darstellung in der Form von Visibility Culling, wie auch für realistische Beleuchtung. Visibility Culling, das den Hauptfokus dieser Arbeit darstellt, ist eine Technik die Ouput-Sensitivität erreichen will, indem nur die sichtbaren Primitive zur Grafikkarte gesandt werden. Trotz der rasanten Entwicklung der Grafikkarten ist Visibility Culling von großer Bedeutung für viele Applikationen, wie Spieleprogrammierung oder Architektur-Design, weil auch die Szenekomplexität entsprechend anwächst. Das Lösen des Sichtbarkeitsproblems war über viele Jahre hinweg ein wichtiges Thema, und unzählige Methoden wurden vorgeschlagen. Interessanterweise gibt es trotzdem immer noch offene Probleme wissenschaftlicher Art, und viele Algorithmen sind entweder unpraktisch oder nur verwendbar für bestimmte Szenenkonfigurationen, wodurch ihre weitläufige Verbreitung verhindert wurde. Sichtbarkeitsberechnungen werden auch benötigt um komplexe Lichtinteraktionen in der Szene zu lösen, von weichen und harten Schatten bis zu Ambient Occlusion und voller Globalen Beleuchtung. Es ist eine riesige Herausforderung, hunderte bis tausende Visibilityanfragen im Bruchteil einer Sekunde zu beantworten um Echtzeit-Laufzeiten zu erreichen. Jenes zu schaffen ist ein Ziel dieser Arbeit.
On the Computation of the 3D Visibility Skeleton
2010
The 3D visibility skeleton is a data structure that encodes the global visibility information of a set of 3D objects. While it is useful in answering global visibility queries, its large size often limits its practical use. In this paper, we address this issue by proposing a subset of the visibility skeleton, which is about 25% to 50% of the whole set. We show that the rest of the data structure can be recovered from the subset as needed, partially or completely. Our recovery method is efficient in the sense that it is output-dependent. We also prove that this subset is minimal for the complexity of our recovery method.
On the three-dimensional visibility skeleton: implementation and analysis
2009
The visibility skeleton is a data structure that encodes global visibility information of a given scene in either 2D or 3D. While this data structure is in principle very useful in answering global visibility queries, its high order worst-case complexity, especially in 3D scene, appears to be prohibitive. However, previous theoretical research has indicated that the expected size of this data structure can be linear under some restricted conditions. This thesis advances the study of the size of the visibility skeleton, namely, using an experimental approach. We first show that, both theoretically and experimentally, the expected size of the visibility skeleton in 2D is linear, and present a linear asymptote that facilitates estimation of the size of the 2D visibility skeleton. We then study the 3D visibility skeleton defined by visual events, which is a subset of the full skeleton defined by Durand et al.. We first present an implementation to compute the vertices of that skeleton for convex disjoint polytopes in general position. This implementation makes it possible to carry on our empirical study in 3D. We consider input scenes that consist of disjoint convex polytopes that approximate randomly distributed unit spheres. We found that, in our setting, the size of the 3D visibility skeleton is quadratically related to the number of the input polytopes and linearly related to the expected silhouette size of the input polytopes.
A new approach of the visibility calculation of an object
International Journal of Manufacturing Technology and Management, 2004
Currently, algorithms of mechanical part visibility determination are slow, because the part surface is cut into numerous elementary surfaces. In this article, we propose to take into account the visibility properties of convex and concave surface patches, in order to treat the object in a global way. This new method is studied on 2D curves, 3D extension is considered.
Revisiting the visibility problem with a hybrid structure paradigm
2015 Latin American Computing Conference (CLEI), 2015
We revisit the problem known as the visibility problem, for computing a potentially visible set of primitives, proposing a solution that can be used to accelerate the processing in real-time 3D visualization applications. We come up with a resulting dry structure in the sense of data reduction that can be used for on-line, interactive applications. Our main goal is to load the minimum amount of primitives from the scene during the rendering stage, as possible. For this purpose, our algorithm executes the culling by using a hybrid paradigm based on viewing-frustum, back-face culling and occlusion models. Results have shown a substantial improvement over these traditional approaches if applied separately. This novel approach can be used in devices with no dedicated processors or with low processing power, as cell phones or embedded displays, or to visualize data through the internet, as in virtual museums applications.
ACM Transactions on Graphics, 2002
Visibility problems are central to many computer graphics applications. The most common examples include hidden-part removal for view computation, shadow boundaries, mutual visibility of objects for lighting simulation. In this paper, we present a theoretical study of 3D visibility properties for scenes of smooth convex objects. We work in the space of light rays, or more precisely, of maximal free segments. We group segments that "see" the same object; this defines the 3D visibility complex. The boundaries of these groups of segments correspond to the visual events of the scene (limits of shadows, disappearance of an object when the viewpoint is moved, etc.). We provide a worst case analysis of the complexity of the visibility complex of 3D scenes, as well as a probabilistic study under a simple assumption for "normal" scenes. We extend the visibility complex to handle temporal visibility. We give an output-sensitive construction algorithm and present applications of our approach.
Conservative visibility preprocessing for complex virtual environments
Virtual Systems and Multimedia, 2001. …, 2001
This paper presents a new approach to visibility culling. We propose a conservative visibility preprocessing method for complex virtual environments. The proposed method deals with general 3D graphical models and invisible polygons jointly blocked by multiple occluders. The ...
Canadian Conference on …, 1997
In this paper we describe a unified data-structure, the 3D Visibility Complex which encodes the visibility information of a 3D scene of polygons and smooth convex objects. This datastructure is a partition of the maximal free segments and is based on the characterization of the topological changes of visibility along critical line sets. We show that the size k of the complex is Ω (n) and O (n4) and we give an output sensitive algorithm to build it in time O ((n3+ k) logn). This theoretical work has already been used to define a ...