We provide control point based necessary and sufficient conditions for (n,m) Bézier surfaces to have linear isoparametric lines. © 2007 Elsevier B.V. All rights reserved.

Spline surfaces are very popular for the modeling of free form surfaces. This is because they are very exible, conceptually simple and the shape can be easily controlled by manipulating control points. However, for complex shapes one has to deal with an overwhelming number of control points. It is therefore increasingly important to build tools that enable the designer to specify only a few geo...

Public-private partnerships (PPPs) are increasingly the vehicles of choice for the implementation of information and communications technology in the developing world. This is particularly true with regard to locally appropriate, shared-access models such as the telecenter franchise. However, the sustainability and the scalability of such initiatives remain in question. This article examines an...

Atmospheric flight phase of a launch vehicle is utilized to evaluate the performance of an H∞ controller in the presence of disturbances. Dynamics of the vehicle is linearly modeled using time-varying parameters. An operating point was found to design a robust command tracker using H∞ control theory that guarantees a stable maneuver. At the end, the controller was employed on the launch vehicle...

We present an interactive learning method that enables a user to iteratively refine a regression model. The user examines the output of the model, visualized as the vertical axis of a 2D scatterplot, and provides corrections by repositioning individual data instances to the correct output level. Each repositioned data instance acts as a control point for altering the learned model, using the ge...

We propose an efficient alignment method for textured DooSabin subdivision surface templates. A variation of the inverse compositional image alignment is derived by introducing smooth adjustments in the parametric space of the surface and relating them to the control point increments. The convergence properties of the proposed method are improved by a coarse-to-fine multiscale matching. The met...