Rune Dalmo

Evaluation of Smooth Spline Blending Surfaces Using GPU

Recent development in several aspects of research on blending type spline constructions has opened up new application areas. We propose a method for evaluation and rendering of smooth blending type spline constructions using the tessellation shader steps of modern graphics hardware. In this preliminary study we focus on concepts and terminology rather than implementation details. Our approach could lead to more efficient, dynamic and stable blending-type spline based applications in fields such as interactive modeling, computer games and more.

Modeling terminal ballistics using blending-type spline surfaces

We explore using GERBS, a blending-type spline construction, to represent deform able thin-plates and model terminal ballistics. Strategies to construct geometry for different scenarios of terminal ballistics are proposed.

Surface deformation over flexible joints using spline blending techniques

Skinning over a skeleton joint is the process of skin deformation based on joint transformation. Popular geometric skinning techniques include implicit linear blending and dual quaternions. Generalized expo-rational B-splines (GERBS) is a blending type spline construction where local functions at each knot are blended by Ck-smooth basis functions. A smooth skinning surface can be constructed over a transformable skeleton joint by combining various types of local surface constructions and applying local Hermite interpolation. Compared to traditional spline methods, increased flexibility and local control with respect to surface deformation can be achieved using the GERBS blending construction. We present a method using a blending-type spline surface for skinning over a flexible joint, where local geometry is individually adapted to achieve natural skin deformation based on skeleton transformations..

Fitting of Discrete Data with GERBS

In this paper, we present a study of fitting discrete data with Generalized Expo-rational B-splines. We investigate different ways to determine interpolation knots and generate GERBS local curves by partitioning the parametric space and solving a corresponding least-squares fitting problem. We apply our technique to discrete evaluations of continuous synthetic benchmark functions and compare the resulting GERBS to the original data with respect to errors and performance.

Multi-source data collection for state-of-the-art data analysis from ground-proximate images in sea ice classification

In modern data analysis it is imperative to use well maintained data sources with curated content. This publication gives an approach for research areas, where there is no such central facility. The specific area used here is sea ice classification from images. The publication is split into two parts. The first part describes the integration of discontinuous sources for different aspects of data needed. The second part describes a simple approach for getting the sea ice concentration from images taken by an ice breaker. The classification is based on the above mentioned multi-source data. We can illustrate that it is possible to combine data from various sources to a central repository and use this repository to obtain the sea ice concentration from images without using any other inputs.

Regression analysis using a blending type spline construction

Regression analysis allows us to track the dynamics of change in measured data and to investigate their properties. A sufficiently good model allows us to predict the behavior of dependent variables with higher accuracy, and to propose a more precise data generation hypothesis.

Spline Representation of Connected Surfaces with Custom-Shaped Holes

Compact surfaces possessing a finite number of boundaries are important to isogeometric analysis (IGA). Generalized expo-rational B-Splines (GERBS) is a blending type spline construction where local functions associated with each knot are blended by \(C^k\)-smooth basis functions. Modeling of surfaces with custom-shaped boundaries, or holes, can be achieved by using certain features and properties of the blending type spline construction, including local refinement and insertion of multiple inner knots. In this paper we investigate representation of arbitrary inner boundaries on parametric surfaces by using the above mentioned blending type spline construction.

Wavelet Compression of Spline Coefficients

Based on a concept for thresholding of wavelet coefficients, which was addressed in [8] and further explored in [6, 7], a method for balancing between non-threshold- and threshold shrinking of wavelet coefficients has emerged. Generalized expo-rational B-splines (GERBS) is a blending type spline construction where local functions at each knot are blended together by \(C^k\)-smooth basis functions. Global data fitting can be achieved with GERBS by fitting local functions to the data. One property of the GERBS construction is an intrinsic partitioning of the global data. Compression of the global data set can be achieved by applying the shrinking strategy to the GERBS local functions. In this initial study we investigate how this affects the resulting GERBS geometry.

Performance of a Wavelet Shrinking Method

A concept for shrinking of wavelet coefficients has been presented and explored in a series of articles [2, 3, 4]. The theory and experiments so far suggest a strategy where the shrinking adapts to local smoothness properties of the original signal. From this strategy we employ partitioning of the global signal and local shrinking under smoothness constraints. Furthermore, we benchmark shrinking of local partitions’ wavelet coefficients utilizing a selection of wavelet basis functions. Then we present and benchmark an adaptive partition-based shrinking strategy where the best performing shrinkage is applied to individual partitions, one at a time. Finally, we compare the local and global benchmark results.

Motion capture data represented using a blending type spline construction

We present a concept for representation of motion-capture data where information from the animation data is used to generate a blending-type spline curve using local curves of Hermite type.