23,735 research outputs found
Construction of a VC1 interpolant over triangles via edge deletion
We present a construction of a visually smooth surface which interpolates to position values and normal vectors of randomly distributed points on a 3D object. The method is local and uses quartic triangular and bicubic quadrilateral patches without splits. It heavily relies on an edge deleting algorithm which, starting from a given triangulation, derives a suitable combination of three- and four sided patches
Evaluation of thermal data for geologic applications
Sensitivity studies using thermal models indicated sources of errors in the determination of thermal inertia from HCMM data. Apparent thermal inertia, with only simple atmospheric radiance corrections to the measured surface temperature, would be sufficient for most operational requirements for surface thermal inertia. Thermal data does have additional information about the nature of surface material that is not available in visible and near infrared reflectance data. Color composites of daytime temperature, nighttime temperature, and albedo were often more useful than thermal inertia images alone for discrimination of lithologic boundaries. A modeling study, using the annual heating cycle, indicated the feasibility of looking for geologic features buried under as much as a meter of alluvial material. The spatial resolution of HCMM data is a major limiting factor in the usefulness of the data for geologic applications. Future thermal infrared satellite sensors should provide spatial resolution comparable to that of the LANDSAT data
A characterization of virtually embedded subsurfaces in 3-manifolds
The paper introduces the spirality character of the almost fiber part for a
closed essentially immersed subsurface of a closed orientable aspherical
3-manifold, which generalizes an invariant due to Rubinstein and Wang. The
subsurface is virtually embedded if and only if the almost fiber part is
aspiral, and in this case, the subsurface is virtually a leaf of a taut
foliation. Besides other consequences, examples are exhibited that
non-geometric 3-manifolds with no Seifert fibered pieces may contain
essentially immersed but not virtually embedded closed subsurfaces.Comment: 28 pages. Errors of previous Proposition 3.1 and Formula 7.2
correcte
Recommended from our members
Girikihaciyan: A Halafian Site in Southeastern Turkey
This report presents the results of excavations undertaken at the site of Girikihaciyan in southeastern Turkey during 1968 and 1970 by the Joint Prehistoric Project, Istanbul-Chicago under the overal direction of Professor Halet Cambel, University of Istanbul, and Professor Robert J. Braidwood, Oriental Institute, University of Chicago.Series: Monographs 3
Constructing IGA-suitable planar parameterization from complex CAD boundary by domain partition and global/local optimization
In this paper, we propose a general framework for constructing IGA-suitable
planar B-spline parameterizations from given complex CAD boundaries consisting
of a set of B-spline curves. Instead of forming the computational domain by a
simple boundary, planar domains with high genus and more complex boundary
curves are considered. Firstly, some pre-processing operations including
B\'ezier extraction and subdivision are performed on each boundary curve in
order to generate a high-quality planar parameterization; then a robust planar
domain partition framework is proposed to construct high-quality patch-meshing
results with few singularities from the discrete boundary formed by connecting
the end points of the resulting boundary segments. After the topology
information generation of quadrilateral decomposition, the optimal placement of
interior B\'ezier curves corresponding to the interior edges of the
quadrangulation is constructed by a global optimization method to achieve a
patch-partition with high quality. Finally, after the imposition of
C1=G1-continuity constraints on the interface of neighboring B\'ezier patches
with respect to each quad in the quadrangulation, the high-quality B\'ezier
patch parameterization is obtained by a C1-constrained local optimization
method to achieve uniform and orthogonal iso-parametric structures while
keeping the continuity conditions between patches. The efficiency and
robustness of the proposed method are demonstrated by several examples which
are compared to results obtained by the skeleton-based parameterization
approach
- …