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1.
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
2.
We establish a lower bound of remote memory references for N-process mutual exclusion algorithms based on reads, writes, or comparison primitives such as test-and-set and compare-and-swap. Our bound improves an earlier lower bound of established by Cypher. Our lower bound is of importance for two reasons. First, it almost matches the time complexity of the best known algorithms based on reads, writes, or comparison primitives. Second, our lower bound suggests
that it is likely that, from an asymptotic standpoint, comparison primitives are no better than reads and writes when implementing
local-spin mutual exclusion algorithms. Thus, comparison primitives may not be the best choice to provide in hardware if one
is interested in scalable synchronization.
Received: January 2002 / Accepted: September 2002
RID="*"
ID="*" Work supported by NSF grants CCR 9732916, CCR 9972211, CCR 9988327, ITR 0082866, and CCR 0208289. 相似文献
3.
Uppaal in a nutshell 总被引:32,自引:0,他引:32
Kim G. Larsen Paul Pettersson Wang Yi 《International Journal on Software Tools for Technology Transfer (STTT)》1997,1(1-2):134-152
4.
Recently, optimization has been used in various ways to interpolate or retarget human body motions obtained by motion-capturing
systems. However, in such cases, the inner structure of a human body has rarely been taken into account, and hence there have
been difficulties in simulating physiological effects such as fatigue or injuries. In this paper, we propose a method to
create/retarget human body motions using a musculoskeletal human body model. Using our method, it is possible to create dynamically
and physiologically feasible motions. Since a muscle model based on Hill's model is included in our system, it is also possible
to retarget the original motion by changing muscular parameters. For example, using the muscle fatigue model, a motion where
a human body gradually gets tired can be simulated. By increasing the maximal force exertable by the muscles, or decreasing
it to zero, training or displacement effects of muscles can also be simulated. Our method can be used for biomechanically
correct inverse kinematics, interpolation of motions, and physiological retargetting of the human body motion. 相似文献
5.
6.
A deformable model of the human iris for measuring small three-dimensional eye movements 总被引:2,自引:0,他引:2
This paper describes a deformable model of the human iris which forms part of a system for accurate off-line measurement
of binocular three-dimensional eye movements, particularly cyclotorsion (torsion), from video image sequences. At least two
existing systems measure torsion from infrared video images by pupil tracking followed by cross correlation using arcs of
bandpass-filtered iris texture. Unfortunately, pupil expansion and contraction reduces the accuracy of this method unless
drugs are used to constrict the pupil, which causes temporary blurred vision. A five-parameter deformable model of the iris
is therefore developed for analysing images obtained without the use of drugs. This model can translate (horizontal and vertical
eye motion), rotate (torsion) and scale both uniformly and radially (pupil changes). Torsion measurements obtained with the
model are repeatable and accurate to within 0.1°; this performance is illustrated by analysing binocular torsion during fixation
on a stationary target.
Received: 27 August 1997 / Accepted: 15 January 1998 相似文献
7.
8.
Yoshimitsu Aoki Shuji Hashimoto Masahiko Terajima Akihiko Nakasima 《The Visual computer》2001,17(2):121-131
We propose a prototype of a facial surgery simulation system for surgical planning and the prediction of facial deformation.
We use a physics-based human head model. Our head model has a 3D hierarchical structure that consists of soft tissue and the
skull, constructed from the exact 3D CT patient data. Anatomic points measured on X-ray images from both frontal and side
views are used to fire the model to the patient's head.
The purposes of this research is to analyze the relationship between changes of mandibular position and facial morphology
after orthognathic surgery, and to simulate the exact postoperative 3D facial shape. In the experiment, we used our model
to predict the facial shape after surgery for patients with mandibular prognathism. Comparing the simulation results and the
actual facial images after the surgery shows that the proposed method is practical. 相似文献
9.
A multimedia application involves information that may be in a form of video, images, audio, text and graphics, need to be
stored, retrieved and manipulated in large databases. In this paper, we propose an object-oriented database schema that supports
multimedia documents and their temporal, spatial and logical structures. We present a document example and show how the schema
can adress all the structures described. We also present a multimedia query specification language that can be used to describe
a multimedia content portion to be retrieved from the database. The language provides means by which the user can specify
the information on the media as well as the temoral and spatial relationships among these media. 相似文献
10.
Wavelet shape blending 总被引:2,自引:0,他引:2
11.
The problem of an instructive and realistic animation and visualization of the shadow- and color-conditions during conjunctions
of actively and passively illuminated cosmic objects has found only particularly satisfying solutions so far. As an example
we study a total solar eclipse. There are didactic shortcomings of specialized astronomical software, even though solutions
have been given, which are very impressive for experts.
Using the possibilities of commercial 3D-animation software we give an object-oriented partial solution. In order to get correct
astronomical representations we model – for different tasks – the object space under cinematic aspects with parameters for
spatial and temporal scaling, for illumination and coloring under couplings of varying strength. The adaptation of the parameters
to optimal acceptance of the spectator must be done a posteriori. 相似文献
12.
This paper proposes a new hand posture identification system which applies genetic algorithm to develop an efficient 3D hand-model-fitting
method. The 3D hand-model-fitting method consists of (1) finding the closed-form inverse kinematics solution, (2) defining
the alignment measure function for the wrist-fitting process, and (3) applying genetic algorithm to develop the dynamic hand
posture identification process. In contrast to the conventional computationally intensive hand-model-fitting methods, we develop
an off-line training process to find the closed-form inverse kinematics solution functions, and a fast model-based hand posture
identification process. In the experiments, we will illustrate that our hand posture identification system is very effective.
Received: 10 April 1997 / Accepted: 18 June 1998 相似文献
13.
Dynamic sculpting and animation of free-form subdivision solids 总被引:3,自引:0,他引:3
Published online: 15 March 2002 相似文献
14.
Through an investigation of how the performance of people who have normal visual capabilities is affected by unimodal, bimodal,
and trimodal feedback, this research establishes a foundation for presenting effective feedback to enhance the performance
of individuals who have visual impairments. Interfaces that employ multiple feedback modalities, such as auditory, haptic,
and visual, can enhance user performance for individuals with barriers limiting one or more channels of perception, such as
a visual impairment. Results obtained demonstrate the effects of different feedback combinations on mental workload, accuracy,
and performance time. Future, similar studies focused on participants with visual impairments will be grounded in this work.
Published online: 6 November 2002 相似文献
15.
We describe a method for simulating the process of cracking based on a 3D physical model. Cracks appear when the stress caused
by internal or external force exceeds the tolerable amount. We applied a spring network model to a simulation of cracks that
appear on drying clay. Clay contracts, or shrinks, as it dries. Because the surface part dries more quickly than the interior,
the stretching stress acts on the surface part, generating cracks. The process of drying changes physical characteristics
such as stiffness and maximum strain. Our model introduces the properties of clay by defining these parameters as functions
of time on the basis of measurement. 相似文献
16.
image-based control or visual servoing approach. It consists of positioning a camera according to the information perceived in the image. This
is thus a very intuitive approach of animation. To be able to react automatically to modifications of the environment, we
also considered the introduction of constraints into the control. This approach is thus adapted to highly reactive contexts
(virtual reality, video games). Numerous examples dealing with classic problems in animation are considered within this framework
and presented in this paper.
Published online: 19 July 2001 相似文献
17.
Dynamic logic (DL) provides a suitable formal framework to model actions and reasoning about them. <$>\cal OASIS<$> is a language
for the specification of object-oriented conceptual models. In our model, specialisation is a relation between classes that
defines an inheritance mechanism through static and dynamic partitions. A variant of DL (including the deontic operators for
permission, prohibition and obligation) is the formalism used in <$>\cal OASIS<$> to deal with changes of state, triggers,
preconditions, protocols and operations. The animation of conceptual models in order to validate the specification is an interesting
topic. We have worked on translating <$>\cal OASIS<$> specifications automatically to concurrent environments in order to
obtain a prototype useful to validate specifications by animation. The aim of this paper is to show that it is feasible to
translate static and dynamic partitions automatically into dynamic logic formulae. Thus, using the same developed schema of
animation it is possible to execute <$>\cal OASIS<$> specifications including inheritance. 相似文献
18.
A model-based hand gesture recognition system 总被引:2,自引:0,他引:2
This paper introduces a model-based hand gesture recognition system, which consists of three phases: feature extraction,
training, and recognition. In the feature extraction phase, a hybrid technique combines the spatial (edge) and the temporal
(motion) information of each frame to extract the feature images. Then, in the training phase, we use the principal component
analysis (PCA) to characterize spatial shape variations and the hidden Markov models (HMM) to describe the temporal shape
variations. A modified Hausdorff distance measurement is also applied to measure the similarity between the feature images
and the pre-stored PCA models. The similarity measures are referred to as the possible observations for each frame. Finally,
in recognition phase, with the pre-trained PCA models and HMM, we can generate the observation patterns from the input sequences,
and then apply the Viterbi algorithm to identify the gesture. In the experiments, we prove that our method can recognize 18
different continuous gestures effectively.
Received: 19 May 1999 / Accepted: 4 September 2000 相似文献
19.