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1.
Optimized triangle mesh reconstruction from unstructured points 总被引:3,自引:1,他引:3
A variety of approaches have been proposed for polygon mesh reconstruction from a set of unstructured sample points. Suffering
from severe aliases at sharp features and having a large number of unnecessary faces, most resulting meshes need to be optimized
using input sample points in a postprocess. In this paper, we propose a fast algorithm to reconstruct high-quality meshes
from sample data. The core of our proposed algorithm is a new mesh evaluation criterion which takes full advantage of the
relation between the sample points and the reconstructed mesh. Based on our proposed evaluation criterion, we develop necessary
operations to efficiently incorporate the functions of data preprocessing, isosurface polygonization, mesh optimization and
mesh simplification into one simple algorithm, which can generate high-quality meshes from unstructured point clouds with
time and space efficiency.
Published online: 28 January 2003
Correspondence to: Y.-J. Liu 相似文献
2.
Curvilinear displacement of free-form-based deformation 总被引:4,自引:0,他引:4
3.
Leif P. Kobbelt 《The Visual computer》2000,16(3-4):142-158
4.
Published online: 14 February 2003 相似文献
5.
Many phenomena in nature and engineering happen simultaneously on rather diverse spatial and temporal scales. In other words,
they exhibit a multi-scale character. A special numerical multilevel technique associated with a particular hierarchical data
structure is adaptive mesh refinement (AMR). This scheme achieves locally very high spatial and temporal resolutions. Due
to its popularity, many scientists are in need of interactive visualization tools for AMR data.
In this article, we present a 3D texture-based volume-rendering algorithm for AMR data that directly utilizes the hierarchical
structure. Thereby fast rendering performance is achieved even for high-resolution data sets. To avoid multiple rendering
of regions that are covered by grids of different levels of resolution, we propose a space partitioning scheme to decompose
the volume into axis-aligned regions of equal-sized cells. Furthermore the problems of interpolation artifacts, opacity corrections,
and texture memory limitations are addressed.
Published online: November 6, 2002
Correspondence to: R. K?hler 相似文献
6.
Interactive surface decomposition for polyhedral morphing 总被引:4,自引:0,他引:4
Arthur Gregory Andrei State Ming C. Lin Dinesh Manocha Mark A. Livingston 《The Visual computer》1999,15(9):453-470
7.
Direct manipulation of FFD: efficient explicit solutions and decomposible multiple point constraints 总被引:8,自引:0,他引:8
Published online: 25 July 2001 相似文献
8.
This paper describes a computer-aided design system for sketching free-form polygonal surfaces such as terrains and other
natural objects. The user manipulates two 3D position and orientation trackers with three buttons, one for each hand. Each
hand has a distinct role to play, with the dominant hand being responsible for picking and manipulation, and the less dominant
hand being responsible for context setting of various kinds. The less dominant hand holds the workpiece, sets which refinement
level that can be picked by the dominant hand, sets the constraint mode and the reshape operator, and generally acts as a
counterpoint to the dominant hand. In this paper, the architecture of the system is outlined, the interaction techniques are
presented, and a simple surface is shown. 相似文献
9.
A convolution surface is an isosurface in a scalar field defined by convolving a skeleton, comprising of points, curves, surfaces,
or volumes, with a potential function. While convolution surfaces are attractive for modeling natural phenomena and objects
of complex evolving topology, the analytical evaluation of integrals of convolution models still poses some open problems.
This paper presents some novel analytical convolution solutions for arcs and quadratic spline curves with a varying kernel.
In addition, we approximate planar higher-degree polynomial spline curves by optimal arc splines within a prescribed tolerance
and sum the potential functions of all the arc primitives to approximate the field for the entire spline curve.
Published online: November 20, 2002 相似文献
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11.
Z -buffer approach, which takes full advantage of the resources already provided in current graphics hardware. We employ a modified
data structure on the light screen's Z-buffer, which dramatically increases the shadowing accuracy. This data structure, the ED-buffer, also simplifies the shadow testing calculations considerably, needing only a couple of fixed-point multiplications and additions
per shadow test. This is ideal for hardware implementation. We also present a technique for optimizing the use of the fixed
memory resource in order to maximize the accuracy of shadowing when the scene is projected from the lighting point of view
on the six faces of a cube surrounding the light source. 相似文献
12.
Summary. In a shared-memory distributed system, n independent asynchronous processes communicate by reading and writing to shared variables. An algorithm is adaptive (to total contention) if its step complexity depends only on the actual number, k, of active processes in the execution; this number is unknown in advance and may change in different executions of the algorithm.
Adaptive algorithms are inherently wait-free, providing fault-tolerance in the presence of an arbitrary number of crash failures and different processes' speed.
A wait-free adaptive collect algorithm with O(k) step complexity is presented, together with its applications in wait-free adaptive alg orithms for atomic snapshots, immediate
snapshots and renaming.
Received: August 1999 / Accepted: August 2001 相似文献
13.
The way in which humans perceive and react to visual complexity is an important issue in many areas of research and application,
particularly because simplification of complex matter can lead to better understanding of both human behaviour in visual control
tasks as well as the visual environment itself. One area of interest is how people perceive their world in terms of complexity
and how this can be modelled mathematically and/or computationally. A prototype model of complexity has been derived using
subcomponents called ‘SymGeons’ (Symmetrical Geometric Icons) based on Biederman’s original Geon Model for human perception.
The SymGeons are primitive shapes which constitute foreground objects. This paper outlines the derivation and ongoing development
of the ‘SymGeon’ model and how it compares to human perception of visual complexity. The application of the model to understanding
complex human-in-the-loop problems associated with visual remote control operations, e.g. control of remotely operated vehicles,
is discussed. 相似文献
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15.
Abstract. Providing a customized result set based upon a user preference is the ultimate objective of many content-based image retrieval
systems. There are two main challenges in meeting this objective: First, there is a gap between the physical characteristics
of digital images and the semantic meaning of the images. Secondly, different people may have different perceptions on the
same set of images. To address both these challenges, we propose a model, named Yoda, that conceptualizes content-based querying
as the task of soft classifying images into classes. These classes can overlap, and their members are different for different
users. The “soft” classification is hence performed for each and every image feature, including both physical and semantic
features. Subsequently, each image will be ranked based on the weighted aggregation of its classification memberships. The
weights are user-dependent, and hence different users would obtain different result sets for the same query. Yoda employs
a fuzzy-logic based aggregation function for ranking images. We show that, in addition to some performance benefits, fuzzy
aggregation is less sensitive to noise and can support disjunctive queries as compared to weighted-average aggregation used
by other content-based image retrieval systems. Finally, since Yoda heavily relies on user-dependent weights (i.e., user profiles)
for the aggregation task, we utilize the users' relevance feedback to improve the profiles using genetic algorithms (GA).
Our learning mechanism requires fewer user interactions, and results in a faster convergence to the user's preferences as
compared to other learning techniques.
Correspondence to: Y.-S. Chen (E-mail: yishinc@usc.edu)
This research has been funded in part by NSF grants EEC-9529152 (IMSC ERC) and IIS-0082826, NIH-NLM R01-LM07061, DARPA and
USAF under agreement nr. F30602-99-1-0524, and unrestricted cash gifts from NCR, Microsoft, and Okawa Foundation. 相似文献
16.
Surface reconstruction from cross-sectional data is important in a variety of applications. It is usually possible to generate
a surface in many ways, but only reasonable ones are acceptable. A surface of minimal area has been considered as one of the
most natural optimal criteria for the original tiling method of surface reconstruction from cross sections. In the paper,
we consider minimal surfaces for continuous generalization of the tiling approach and in the general situation of reconstruction
from cross sections. We show that in these cases the minimal area criterion leads to defective surfaces and is thus unacceptable.
Published online: 23 July 2002
Correspondence to: D. Berzin 相似文献
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18.
Shape understanding by contour-driven retiling 总被引:1,自引:0,他引:1
Published online: 14 February 2003 相似文献
19.
Published online: 14 February 2003 相似文献
20.