Identifying Similar Surface Patches on Proteins Using a Spin-Image Surface Representation

2005 ◽  
pp. 417-428 ◽  
Author(s):  
Mary Ellen Bock ◽  
Guido M. Cortelazzo ◽  
Carlo Ferrari ◽  
Concettina Guerra
Keyword(s):  
Surface Representation ◽  
Surface Patches ◽  
Spin Image

The Memory of the Ground Surface Representation for Space Perception

2008 ◽  
Author(s):  
Lei Zhu ◽  
Zijiang J. He ◽  
Teng Leng Ooi
Keyword(s):  
Ground Surface ◽  
Space Perception ◽  
Surface Representation

THE EXISTENCE OF SURFACE PATCHES FOR PERIODIC MINIMAL SURFACES

1990 ◽  
Vol 51 (C7) ◽  
pp. C7-265-C7-271 ◽  
Author(s):  
J. C.C. NITSCHE
Keyword(s):  
Minimal Surfaces ◽  
Surface Patches

Computation of Self-Intersections of Offsets of Be´zier Surface Patches

1997 ◽  
Vol 119 (2) ◽  
pp. 275-283 ◽  
Author(s):  
Takashi Maekawa ◽  
Wonjoon Cho ◽  
Nicholas M. Patrikalakis
Keyword(s):  
Differential Geometry ◽  
Distance Function ◽  
Polynomial Equations ◽  
Intersection Curve ◽  
Parameter Domain ◽  
Surface Patches ◽  
Intersection Curves

Self-intersection of offsets of regular Be´zier surface patches due to local differential geometry and global distance function properties is investigated. The problem of computing starting points for tracing self-intersection curves of offsets is formulated in terms of a system of nonlinear polynomial equations and solved robustly by the interval projected polyhedron algorithm. Trivial solutions are excluded by evaluating the normal bounding pyramids of the surface subpatches mapped from the parameter boxes computed by the polynomial solver with a coarse tolerance. A technique to detect and trace self-intersection curve loops in the parameter domain is also discussed. The method has been successfully tested in tracing complex self-intersection curves of offsets of Be´zier surface patches. Examples illustrate the principal features and robustness characteristics of the method.

A Smooth Contact Algorithm Using Cubic Spline Surface Interpolation for Rigid and Flexible Bodies

2013 ◽  
Author(s):  
Juhwan Choi ◽  
Jin Hwan Choi
Keyword(s):  
Contact Force ◽  
Cubic Spline ◽  
Surface Representation ◽  
Flexible Bodies ◽  
Contact Algorithm ◽  
Surface Interpolation ◽  
Spline Surface ◽  
Smooth Contact ◽  
Representation Method ◽  
Detailed Search

The contact analysis of multi-flexible-body dynamics (MFBD) has been an important issue in the area of computational dynamics because the realistic dynamic analysis of many mechanical systems includes the contacts among rigid and flexible bodies. But, until now, the contact analysis in the multi-flexible-body dynamics has still remained as a big, challenging area. Especially, the most of contact algorithms have been developed based on the facetted triangles. As a result, the contact force based on the facetted surface was not accurate and smooth because the geometrical error is already included in the contact surface representation stage. This kind of error can be very important in the precise mechanism such as gear contact or cam-valve contact problems. In order to resolve this problem, this study suggests a cubic spline surface representation method and related contact algorithms. The proposed contact algorithms are using the compliant contact force model based on the Hertzian contact theory. In order to evaluate the smooth contact force, the penetration depth and contact normal directions are evaluated by using the cubic spline surface interpolation. Also, for the robust and efficient contact algorithm development, the contact algorithms are divided into four main parts which are a surface representation, a pre-search, a detailed search and a contact force generation. In the surface representation part, we propose a smooth surface representation method which can be used for smooth rigid and flexible bodies. In the pre-search, the algorithm performs collision detection and composes the expected contact pairs for the detailed search. In the detailed search, the penetration depth and contact reference frame are calculated with the cubic spline surface interpolation in order to generate the accurate and smooth contact force. Finally in the contact force generation part, we evaluate the contact force and Jacobian matrix for the implicit time integrator.

Ray tracing parametric surface patches utilizing numerical techniques and ray coherence

1986 ◽  
Vol 20 (4) ◽  
pp. 279-285 ◽  
Author(s):  
Kenneth I. Joy ◽  
Murthy N. Bhetanabhotla
Keyword(s):  
Ray Tracing ◽  
Parametric Surface ◽  
Numerical Techniques ◽  
Surface Patches

3-D prestack Kirchhoff beam migration for depth imaging

Geophysics ◽  
2000 ◽  
Vol 65 (5) ◽  
pp. 1592-1603 ◽  
Author(s):  
Yonghe Sun ◽  
Fuhao Qin ◽  
Steve Checkles ◽  
Jacques P. Leveille
Keyword(s):  
Distributed Environment ◽  
Small Surface ◽  
Depth Imaging ◽  
Depth Migration ◽  
Kirchhoff Migration ◽  
Surface Patches ◽  
Image Volume ◽  
Kirchhoff Depth Migration ◽  
Full Volume ◽  
Single Set

A beam implementation is presented for efficient full‐volume 3-D prestack Kirchhoff depth migration of seismic data. Unlike conventional Kirchhoff migration in which the input seismic traces in time are migrated one trace at a time into the 3-D image volume for the earth’s subsurface, the beam migration processes a group of input traces (a supergather) together. The requirement for a supergather is that the source and receiver coordinates of the traces fall into two small surface patches. The patches are small enough that a single set of time maps pertaining to the centers of the patches can be used to migrate all the traces within the supergather by Taylor expansion or interpolation. The migration of a supergather consists of two major steps: stacking the traces into a τ-P beam volume, and mapping the beams into the image volume. Since the beam volume is much smaller than the image volume, the beam migration cost is roughly proportional to the number of input supergathers. The computational speedup of beam migration over conventional Kirchhoff migration is roughly proportional to [Formula: see text], the average number of traces per supergather, resulting a theoretical speedup up to two orders of magnitudes. The beam migration was successfully implemented and has been in production use for several years. A factor of 5–25 speedup has been achieved in our in‐house depth migrations. The implementation made 3-D prestack full‐volume depth imaging feasible in a parallel distributed environment.

scholarly journals On-line construction of the upper envelope of triangles and surface patches in three dimensions

1996 ◽  
Vol 5 (6) ◽  
pp. 303-320 ◽  
Author(s):  
Jean-Daniel Boissonnat ◽  
Katrin T.G. Dobrindt
Keyword(s):  
Three Dimensions ◽  
Surface Patches ◽  
On Line ◽  
Line Construction
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