| 1. |
- Brun, Anders, 1976-, et al.
(författare)
-
Similar Tensor Arrays : A Framework for Storage of Tensor Array Data
- 2009. - 1
-
Ingår i: Tensors in Image Processing and Computer Vision. - London : Springer. - 9781848822986 - 9781848822993 ; , s. 407-428
-
Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- Abstract This chapter describes a framework for storage of tensor array data, useful to describe regularly sampled tensor fields. The main component of the framework, called Similar Tensor Array Core (STAC), is the result of a collaboration between research groups within the SIMILAR network of excellence. It aims to capture the essence of regularly sampled tensor fields using a minimal set of attributes and can therefore be used as a “greatest common divisor” and interface between tensor array processing algorithms. This is potentially useful in applied fields like medical image analysis, in particular in Diffusion Tensor MRI, where misinterpretation of tensor array data is a common source of errors. By promoting a strictly geometric perspective on tensor arrays, with a close resemblance to the terminology used in differential geometry, (STAC) removes ambiguities and guides the user to define all necessary information. In contrast to existing tensor array file formats, it is minimalistic and based on an intrinsic and geometric interpretation of the array itself, without references to other coordinate systems.
|
|
| 2. |
- Brun, Anders, 1976-, et al.
(författare)
-
Tensor Glyph Warping : Visualizing Metric Tensor Fields using Riemannian Exponential Maps
- 2009. - XVII
-
Ingår i: Visualization and Processing of Tensor Fields. - Berlin Heidelberg : Springer. - 9783540883777 - 9783540883784 ; , s. 139-160
-
Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- The Riemannian exponential map, and its inverse the Riemannian logarithm map, can be used to visualize metric tensor fields. In this chapter we first derive the well-known metric sphere glyph from the geodesic equation, where the tensor field to be visualized is regarded as the metric of a manifold. These glyphs capture the appearance of the tensors relative to the coordinate system of the human observer. We then introduce two new concepts for metric tensor field visualization: geodesic spheres and geodesically warped glyphs. These extensions make it possible not only to visualize tensor anisotropy, but also the curvature and change in tensor-shape in a local neighborhood. The framework is based on the exp p (v i ) and log p (q) maps, which can be computed by solving a second-order ordinary differential equation (ODE) or by manipulating the geodesic distance function. The latter can be found by solving the eikonal equation, a nonlinear partial differential equation (PDE), or it can be derived analytically for some manifolds. To avoid heavy calculations, we also include first- and second-order Taylor approximations to exp and log. In our experiments, these are shown to be sufficiently accurate to produce glyphs that visually characterize anisotropy, curvature, and shape-derivatives in sufficiently smooth tensor fields where most glyphs are relatively similar in size.
|
|
| 3. |
- Svensson, Björn, et al.
(författare)
-
On Geometric Transformations of Local Structure Tensors
- 2009. - 1
-
Ingår i: Tensors in Image Processing and Computer Vision. - London : Springer. - 9781848822986 - 9781848822993 ; , s. 179-193
-
Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- The structure of images has been studied for decades and the use of local structure tensor fields appeared during the eighties [3, 14, 6, 9, 11]. Since then numerous varieties of tensors and estimation schemes have been developed. Tensors have for instance been used to represent orientation [7], velocity, curvature [2] and diffusion [19] with applications to adaptive filtering [8], motion analysis [10] and segmentation [17]. Even though sampling in non-Cartesian coordinate system are common, analysis and processing of local structure tensor fields in such systems is less developed. Previous work on local structure in non-Cartesian coordinate systems include [21, 16, 1, 18].
|
|
| 4. |
- Forsberg, Daniel, et al.
(författare)
-
Adaptive Anisotropic Regularization of Deformation Fields for Non-Rigid Registration
- 2010
-
Ingår i: IEEE International Conference on Acoustics, Speech, and Signal Processing. - : IEEE. - 9781424442966 - 9781424442959 ; , s. 473-476
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Image registration is a crucial task in many applications and applied in a variety of different areas. In addition to the primary task of image alignment, the deformation field is valuable when studying structural/volumetric changes in the brain. In most applications a regularizing term is added to achieve a smoothly varying deformation field. This can sometimes cause conflicts in situations of local complex deformations. In this paper we present a new regularizer, which aims at handling local complex deformations while maintaining an overall smooth deformation field. It is based on an adaptive anisotropic regularizer and its usefulness is demonstrated by two examples, one synthetic and one with real MRI data from a pre- and post-op situation with normal pressure hydrocephalus.
|
|
| 5. |
- Johansson, Tobias, 1977-, et al.
(författare)
-
Transaction Cost Economics
- 2020
-
Ingår i: Theories and Perspectives in Business Administration. - Lund : Studentlitteratur AB. - 9789144127088 ; , s. 145-167
-
Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- Introduction: Why do firms exist? Please close your eyes and give this question a couple of minutes of thought! Of course, there are many potential answers to such a question, and in the history of human thought, there have been multiple answers to similar but different ontological questions. Two potential answers could be 1) that there is a divine force that guarantees its existence and rationale (Descartes, 1670/1901) or 2) that firms are merely a consequence of historical events leading to the emergence of complexity (Darwin, 1859/2004) and that there is no teleology at all in relation to the concept of the firm. It just exists because it has evolved. Perhaps, these are not the most apparent sources of inspiration that students of business administration would, or should, use to try to answer such a question. If you had been a student of business administration or economics before 1937, however, these would have been sources of inspiration that you would have had to turn to. Because at that time, no real account of this question was available in economic theories.
|
|
| 6. |
- Knutsson, Hans, 1950-, et al.
(författare)
-
Learning Multidimensional Signal Processing
- 1998
-
Ingår i: Proceedings of the 14th International Conference on Pattern Recognition, vol 2. - Linköping, Sweden : Linköping University, Department of Electrical Engineering. ; , s. 1416-1420
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- This paper presents our general strategy for designing learning machines as well as a number of particular designs. The search for methods allowing a sufficient level of adaptivity are based on two main principles: 1. Simple adaptive local models and 2. Adaptive model distribution. Particularly important concepts in our work is mutual information and canonical correlation. Examples are given on learning feature descriptors, modeling disparity, synthesis of a global 3-mode model and a setup for reinforcement learning of online video coder parameter control.
|
|
| 7. |
- Nordberg, Klas, et al.
(författare)
-
On the Equivariance of the Orientation and the Tensor Field Representation
- 1993
-
Ingår i: SCIA8. - Linköping, Sweden : Linköping University, Department of Electrical Engineering. - 8299287200 ; , s. 57-63
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The tensor representation has proven a successful tool as a mean to describe local multi-dimensional orientation. In this respect, the tensor representation is a map from the local orientation to a second order tensor. This paper investigates how variations of the orientation are mapped to variation of the tensor, thereby giving an explicit equivariance relation. The results may be used in order to design tensor based algorithms for extraction of image features defined in terms of local variations of the orientation, e.g. multi-dimensional curvature or circular symmetries. It is assumed that the variation of the local orientation can be described in terms of an orthogonal transformation group. Under this assumption a corresponding orthogonal transformation group, acting on the tensor, is constructed. Several correspondences between the two groups are demonstrated.
|
|
| 8. |
- Wiklund, Johan, et al.
(författare)
-
Hierarchical Phase Based Disparity Estimation
- 1992
-
Ingår i: Proceedings of 2nd Singapore International Conference on Image Processing. - Linköping, Sweden : Linköping University, Department of Electrical Engineering. - 9789810211820 - 9810211821
-
Rapport (övrigt vetenskapligt/konstnärligt)
|
|
| 9. |
-
Forskning om personlig assistans : en antologi
- 2018
-
Samlingsverk (redaktörskap) (övrigt vetenskapligt/konstnärligt)abstract
- Förord I januari 2018 träffade branschorganisationen KFO Personlig Assistans en grupp forskare och den tidigare socialministern Bengt Westerberg, för att prata om forskningens betydelse för den personliga assistansen. Vi kunde då konsta- tera att det finns mycket forskning på området, men att forskningen till stora delar är okänd och sällan använd eller refererad. Idén om en antologi med en mer lättillgänglig beskrivning av forskningen tog form. En redaktion utsågs och en referensgrupp med representanter för funktionshinder- och brukarrörelsen tillsattes. Nu, knappt ett år senare, presenterar 21 forskare här sitt material i en antologi som belyser flera olika perspektiv och spänner över de senaste tio årens forskning inom personlig assistans. Antologin kan med fördel användas både som en över- blick över vilken forskning som är gjord och som en källa att ösa ur för den som vill lära. Med stort tack till alla medverkande och ett särskilt tack till redaktionen,
|
|
| 10. |
|
|
