scholarly journals Can local NURBS refinement be achieved by modifying only the user interface?

2021 ◽  
Author(s):  
Neil Dodgson ◽  
J Kosinka
Keyword(s):  
User Interface ◽  
Data Structures ◽  
Control Point ◽  
Control Points ◽  
Control Mesh

© 2015 The Authors. NURBS patches have a serious restriction: they are constrained to a strict rectangular topology. This means that a request to insert a single new control point will cause a row of control points to appear across the NURBS patch, a global refinement of control. We investigate a method that can hide unwanted control points from the user so that the user's interaction is with local, rather than global, refinement. Our method requires only straightforward modification of the user interface and the data structures that represent the control mesh, making it simpler than alternatives that use hierarchical or T-constructions. Our results show that our method is effective in many cases but has limitations where inserting a single new control point in certain cases will still cause a cascade of new control points to appear across the NURBS patch.

scholarly journals Can local NURBS refinement be achieved by modifying only the user interface?

2020 ◽  
Author(s):  
Neil Dodgson ◽  
J Kosinka
Keyword(s):  
User Interface ◽  
Data Structures ◽  
Control Point ◽  
Control Points ◽  
Control Mesh

© 2015 The Authors. NURBS patches have a serious restriction: they are constrained to a strict rectangular topology. This means that a request to insert a single new control point will cause a row of control points to appear across the NURBS patch, a global refinement of control. We investigate a method that can hide unwanted control points from the user so that the user's interaction is with local, rather than global, refinement. Our method requires only straightforward modification of the user interface and the data structures that represent the control mesh, making it simpler than alternatives that use hierarchical or T-constructions. Our results show that our method is effective in many cases but has limitations where inserting a single new control point in certain cases will still cause a cascade of new control points to appear across the NURBS patch.

scholarly journals Can local NURBS refinement be achieved by modifying only the user interface?

2020 ◽  
Author(s):  
Neil Dodgson ◽  
J Kosinka
Keyword(s):  
User Interface ◽  
Data Structures ◽  
Control Point ◽  
Control Points ◽  
Control Mesh

© 2015 The Authors. NURBS patches have a serious restriction: they are constrained to a strict rectangular topology. This means that a request to insert a single new control point will cause a row of control points to appear across the NURBS patch, a global refinement of control. We investigate a method that can hide unwanted control points from the user so that the user's interaction is with local, rather than global, refinement. Our method requires only straightforward modification of the user interface and the data structures that represent the control mesh, making it simpler than alternatives that use hierarchical or T-constructions. Our results show that our method is effective in many cases but has limitations where inserting a single new control point in certain cases will still cause a cascade of new control points to appear across the NURBS patch.

scholarly journals Can local NURBS refinement be achieved by modifying only the user interface?

2021 ◽  
Author(s):  
Neil Dodgson ◽  
J Kosinka
Keyword(s):  
User Interface ◽  
Data Structures ◽  
Control Point ◽  
Control Points ◽  
Control Mesh

© 2015 The Authors. NURBS patches have a serious restriction: they are constrained to a strict rectangular topology. This means that a request to insert a single new control point will cause a row of control points to appear across the NURBS patch, a global refinement of control. We investigate a method that can hide unwanted control points from the user so that the user's interaction is with local, rather than global, refinement. Our method requires only straightforward modification of the user interface and the data structures that represent the control mesh, making it simpler than alternatives that use hierarchical or T-constructions. Our results show that our method is effective in many cases but has limitations where inserting a single new control point in certain cases will still cause a cascade of new control points to appear across the NURBS patch.

scholarly journals Control point insertion for B-spline curves

1988 ◽  
Vol 38 (2) ◽  
pp. 307-313 ◽  
Author(s):  
Heinz H. Gonska ◽  
Andreas Röth
Keyword(s):  
User Interface ◽  
Control Point ◽  
Point Of View ◽  
Control Points ◽  
Natural User Interface ◽  
B Spline ◽  
Spline Curves

Inserting new knots into B-spline curves is a well-known technique in CAGD to gain extra flexibility for design purposes. However, from a user's point of view, the insertion of knots is somewhat unsatisfactory since the newly generated control points sometimes show up in unexpected locations. The aim of this note is to show that these problems can be circumvented by inserting the control vertices directly, thus also providing a more natural user interface.

scholarly journals Analysis of the Effect of Different Combinations of Observation Satellites on the Resolving Accuracy of GNSS Observation Data

2020 ◽  
Vol 206 ◽  
pp. 03025
Author(s):  
Junze Wang ◽  
Maohua Yao ◽  
Wenting Zhou ◽  
Xiangping Chen
Keyword(s):  
Measurement Accuracy ◽  
Control Point ◽  
Satellite System ◽  
Base Stations ◽  
Observation Data ◽  
Control Points ◽  
Level Control ◽  
Satellite Systems ◽  
Beidou Navigation Satellite System ◽  
Stable Measurement

In this paper, 24 C-level control points under different terrain conditions were selected to be the testing points. The binary-satellite system (GPS+GLONASS) and the triple-satellite system with BeiDou Navigation Satellite System (BDS) (BDS+GPS+GLONASS) were adopted for static measurement; and the observation data from BeiDou Ground-based Augumentation System (GBAS) base stations in Guangxi were collected for solution. By comparing the residuals of GPS tri-dimensional baseline vectors and the internal accord accuracy of each control point under the binary and triple-satellite systems, the effect of data collected by different satellite systems under different terrain conditions on measurement accuracy was studied. According to the results, (1) the triple-satellite system with BDS showed more stable measurement accuracy; (2) in plane, the two systems were of equivalent measurement accuracy in mountainous and flat areas; in elevation, the triple-satellite system showed higher and more stable measurement accuracy.

scholarly journals MULTIRESOLUTION CONTROL OF CURVES AND SURFACES WITH A SELF-SIMILAR MODEL

Fractals ◽  
2010 ◽  
Vol 18 (03) ◽  
pp. 271-286 ◽  
Author(s):  
HOUSSAM HNAIDI ◽  
ERIC GUÉRIN ◽  
SAMIR AKKOUCHE
Keyword(s):  
Wavelet Transform ◽  
Control Point ◽  
Iterated Function Systems ◽  
Control Points ◽  
Similar Model ◽  
Surface Theory ◽  
Curves And Surfaces ◽  
Iterated Function ◽  
Resolution Level ◽  
Self Similar

This paper presents two self-similar models that allow the control of curves and surfaces. The first model is based on IFS (Iterated Function Systems) theory and the second on subdivision curve and surface theory. Both of these methods employ the detail concept as in the wavelet transform, and allow the multiresolution control of objects with control points at any resolution level.In the first model, the detail is inserted independently of control points, requiring it to be rotated when applying deformations. In contrast, the second method describes details relative to control points, allowing free control point deformations.Modeling examples of curves and surfaces are presented, showing manipulation facilities of the models.

Smoothness of C-Bezier Curves

2000 ◽  
Author(s):  
Manhong Wen ◽  
Kwun-Lon Ting
Keyword(s):  
Shape Control ◽  
Control Point ◽  
Design Procedure ◽  
Design Parameters ◽  
Control Points ◽  
Bezier Curves ◽  
Bézier Curves ◽  
Point Distribution ◽  
G1 Continuity ◽  
G2 Continuity

Abstract This paper presents G1 and G2 continuity conditions of c-Bezier curves. It shows that the collinear condition for G1 continuity of Bezier curves is generally no longer necessary for c-Bezier curves. Such a relaxation of constraints on control points is beneficial from the structure of c-Bezier curves. By using vector weights, each control point has two extra free design parameters, which offer the probability of obtaining G1 and G2 continuity by only adjusting the weights if the control points are properly distributed. The enlargement of control point distribution region greatly simplifies the design procedure to and enhances the shape control on constructing composite curves.

G1 Continuity of C-Bezier Rectangular Surfaces

2000 ◽  
Author(s):  
Manhong Wen ◽  
Kwun-Lon Ting
Keyword(s):  
Control Point ◽  
Sufficient Conditions ◽  
Necessary And Sufficient Conditions ◽  
Design Parameters ◽  
Control Points ◽  
Bézier Surfaces ◽  
G1 Continuity ◽  
Bezier Surfaces ◽  
Necessary And Sufficient

Abstract This paper probes G1 continuity between two adjacent c-Bezier rectangular patches. The necessary and sufficient conditions are derived. It shows that the coplanar condition for G1 continuity of two adjacent Bezier patches is not necessary for c-Bezier patches. Such a relaxation of constraints on control points is beneficial from vector weights of c-Bezier surfaces, which leads to two extra free design parameters for each control point. C-Bezier surfaces offer the possibility of obtaining G1 continuity by just adjusting the weights, which greatly simplifies the design to construct composite surfaces.

scholarly journals Research on the Characteristics of Infrared Radiation Spectra at Zigong Acupoint within Menstrual Cycle of Healthy Female

2019 ◽  
Vol 2019 ◽  
pp. 1-8 ◽  
Author(s):  
Meng Qin ◽  
Si-qi Ma ◽  
Zhi-ming Huang ◽  
Xue-yong Shen ◽  
Jian-zi Wei
Keyword(s):  
Menstrual Cycle ◽  
Radiation Intensity ◽  
Infrared Radiation ◽  
Statistical Difference ◽  
Radiation Spectrum ◽  
Control Point ◽  
Control Points ◽  
Total Radiation ◽  
Healthy Female ◽  
The Right

The purpose of this study was to observe the characteristics of infrared radiation spectrum of Zigong acupoint (EX-CA1) within the menstrual cycle of healthy female. We used highly sensitive infrared radiation spectrum detection system and phase-locked amplification technology to detect and analyse the infrared radiation spectrum from 1.5μm to 18μm of 32 healthy female before, during, and after menstruation at EX-CA1 and control points. The results showed that the total radiation intensity of left EX-CA1 was significantly higher than that of left control point (P<0.05) at the whole menstrual cycle, and the difference between right EX-CA1 and right control points was statistically significant before and after menstruation (P<0.05), no statistical difference during menstruation. Previous studies found that the radiation near 15μm was correlated with glucose metabolism. The results of this study showed that there were statistical differences in 10 wavelengths between left EX-CA1 and left control point from 14μm to 18μm, and there were statistical differences in 3 wavelengths on the right side (P<0.05). The left side is more prominent than the right side. The infrared radiation intensity of EX-CA1 decreased gradually with the change of cycle rhythm within menstrual cycle, but there was no statistical difference in this trend. There was no statistical difference in total radiation intensity between the right and left side of EX-CA1. Compared with the control points, the number of different wavelengths between left EX-CA1 and left control point during menstruation was significantly larger than that between right EX-CA1 and right control point (P<0.001). The results indicated that the energy of EX-CA1 was higher than control points. There was no difference in the radiation intensity between the right and left sides of EX-CA1 but there was acupoint laterality compared with nonacupoints. There was no significant rhythmic change in infrared radiation intensity of EX-CA1 during the menstrual cycle.

scholarly journals Evaluation of Photogrammetry and Inclusion of Control Points: Significance for Infrastructure Monitoring

Data ◽  
2019 ◽  
Vol 4 (1) ◽  
pp. 42 ◽  
Author(s):  
Renee Oats ◽  
Rudiger Escobar-Wolf ◽  
Thomas Oommen
Keyword(s):  
Laser Scanning ◽  
Retaining Wall ◽  
Control Point ◽  
Wall Structure ◽  
Control Points ◽  
Point Selection ◽  
Cloud Data ◽  
Infrastructure Monitoring ◽  
Mode Behavior ◽  
The Impact

Structure from Motion (SfM)/Photogrammetry is a powerful mapping tool in extracting three-dimensional (3D) models from photographs. This method has been applied to a range of applications, including monitoring of infrastructure systems. This technique could potentially become a substitute, or at least a complement, for costlier approaches such as laser scanning for infrastructure monitoring. This study expands on previous investigations, which utilize photogrammetry point cloud data to measure failure mode behavior of a retaining wall model, emphasizing further robust spatial testing. In this study, a comparison of two commonly used photogrammetry software packages was implemented to assess the computing performance of the method and the significance of control points in this approach. The impact of control point selection, as part of the photogrammetric modeling processes, was also evaluated. Comparisons between the two software tools reveal similar performances in capturing quantitative changes of a retaining wall structure. Results also demonstrate that increasing the number of control points above a certain number does not, necessarily, increase 3D modeling accuracies, but, in some cases, their spatial distribution can be more critical. Furthermore, errors in model reproducibility, when compared with total station measurements, were found to be spatially correlated with the arrangement of control points.

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