Interactive modeling enhanced with constraints and physics with applications in molecular modeling

Surles, Mark C.

doi:10.1145/147156.147196

Cited by 8 publications

(2 citation statements)

References 15 publications

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“…The differential control methods employed in this paper are formally more closely allied to the methods of constrained dynamic simulation described in [29,2,19,31,23] than to the positional optimization methods cited above. Some of the issues involved in adapting these methods to differential kinematic control are addressed in [13], while [27] considers their application to the design of free form surfaces, and [12] illustrates their use in a constraint-based drawing program.…”

Section: Relatedmentioning

confidence: 99%

Camera control in computer graphics

Christie

Olivier

2009

ACM SIGGRAPH ASIA 2009 Courses

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Camera control is essential in both virtual and real-world environments. The quality of the camera's placement and motion may spell the difference between usability and confusion. Our work focuses on an instance of camera control called target following, and offers an algorithm for following multiple targets with unpredictable tra-jectories, among known obstacles. To the best of our knowledge, this work is the first attempting to address this important problem. 1 Our Method and Results In multi-targets following, the camera's primary objective is to follow and maximize visibility of multiple moving targets. For example , in video games, a third-person view camera may be controlled to follow a group of characters through complicated virtual environments. In robotics, a camera attached to robotic manipula-tors could also be controlled to observe live performers in a concert , monitor assembly of a mechanical system, or maintain task visibility during teleoperated surgical procedures. In general, it is difficult for a user to manually control the camera while also concentrating on other critical tasks. Therefore, it is desirable to have an autonomous camera system that handles the camera movement. The camera control problem has been studied extensively in both computer graphics and robotics (see a recent survey [Christie et al. 2008]) because of its broad applications. Unfortunately, many of these methods are not applicable to real-time multi-targets following among obstacles. The problem of building a camera for following the targets can be viewed as an online motion planning problem, in which the planner must be able to generate a trajectory for the camera and predict targets' motions in real time. In this poster, we present a sampling-based planner to robustly follow multiple targets among obstacles. We assume that the workspace is populated with known obstacles represented by polygons. These polygons are the projection of 3D objects that can potentially block the camera's view. This projection essential reduces our problem to a 2D workspace. We assume that, initially, the targets T are visible by the camera C, and, during the entire simulation, T exhibit certain degree of coherence (similar to a flock of bird). The targets are either controlled by the user or by another program, so the trajectories of the targets are not known in advance. However we assume that the maximum (linear) velocity of the target, v max T , is known. The current positions X T (t) of some targets T ⊂ T at time t are known only if T is in C's view range. The camera C also has bounded linear velocity v max C. The camera C's view range VC is defined as a tuple: VC = (θ, rnear, r f ar), where θ is the view angle, and rnear and r f ar define the near and far view range. The exact configuration of this view range at time t, denoted as VC (t), is defined by the tuple and the camera's location xC (t). The position xC of the camera is simply governed by the following linear equation: xC (t + t) = xC (t) + t · vC (t). The problem of target followi...

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Section: Relatedmentioning

confidence: 99%

Camera control in computer graphics

Christie

Olivier

2009

ACM SIGGRAPH ASIA 2009 Courses

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“…Halstead et al [6] implemented smooth interpolation with Catmull-Clark surfaces using a thin-plate energy functional. Other relevant work of physical models include the realistic animation of volumetric objects and molecular structure [12,19,20,24], and the direct manipulation of spline models [4,7]. Chrr method dynamically sculpts spline objects controlled by physical laws subject to various constraints.…”

Section: Related Workmentioning

confidence: 99%

Haptic sculpting of dynamic surfaces

Dachille

Qin

Kaufman

et al. 1999

Proceedings of the 1999 Symposium on Interactive 3D Graphics

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Conventional free-form surface design usually require tedious control-point manipulation and/or painstaking constraint specification via unnatural mouse-based interfaces. This paper presents a novel haptic approach for the direct manipulation of physics-based B-spline surfaces. Our method permits users to interactively sculpt virtual yet real material with a standard haptic device, and feel the physically realistic presence of virtual B-spline objects with force feedback throughout the design process. We aim to develop various haptic sculpting tools to expedite the direct manipulation of B-spline surfaces with haptic feedback and constraints. One significant contribution of this paper is that point, normal, and curvature constraints can be specified interactively and modified naturally using forces. We propose and formulate a dual representation for Bspline surfaces in both physical and mathematical space. This massspring model is mathematically constrained by the B-spline surface throughout the sculpting session. The equations of motion controlling the physical behavior of the B-spline surface are solved using a tractable numerical solver in real-time. The integration of haptics with traditional geometric modeling will increase the bandwidth of human-computer interaction, and thus shorten the time-consuming design cycle. We envision that this integrated approach promises a much greater potential in computer-integrated design and manufacturing, haptic interface, interactive graphics, medical applications, and virtual environments.

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