Numero 38

fredag 6 december 1996, årgång 26

Veckoblad om forskning, undervisning och administration m.m.
NADA - Institutionen för numerisk analys och datalogi, KTH


Aktuellt kalendarium (inte kalendariet som hör specifikt till denna Numeroutgåva).

Docentföreläsning: Stereoscopic Vision by Man and Machine

Jonas Gårding håller docentföreläsning under ovanstående rubrik på måndag (9 dec.) kl. 15.00 i sal D2 (Lindstedtsv. 5).


The perspective views of the world obtained by our left and right eyes are slightly different, by virtue of each eye's different viewing angle. It is a remarkable fact that instead of seeing these two views superimposed in a double image, we perceive a single image augmented by the depth shape of the object we are fixating. This phenomenon, known as stereopsis, has provoked interest for several centuries and leads to intriguing problems in geometry and computational theory as well as in psychophysics and neurophysiology, to name but a few of the disciplines involved. Our current understanding of the process is to a very large extent based on the foundations laid by Helmholtz in the previous century. In recent years the emergence of binocular robotic vision systems has stimulated a renewed surge of interest in the geometric and computational aspects of stereopsis.

In this talk I will review some basic facts and theory regarding stereoscopic vision. I will then described some recent work performed in collaboration with the AI Vision Research Unit at Sheffield University, aimed at determining the nature of the three-dimensional information that is provided by stereopsis. According to this theory, the human stereoscopic visual system does not provide a representation of the world in terms of ordinary Euclidean geometry, but rather as an equivalence class of shapes related by so-called relief transformations. I will also describe a computer implementation of the theory, which allows binocular machine vision systems to perform certain common visual tasks without prior calibration of the camera geometry.

I korthet

Pengar: Information från EU/FoU-rådet finns på En förteckning över aktuella ansökningsomgångar inom EU:s fjärde ramprogram finns på

Tjänst: Universitetslektor i datalogi och numerisk analys vid Lunds Tekniska Högskola. Sista ansökningsdag är den 18 december. Numeropärmen 96.151

Disputation: Compilation Techniques for Prolog, Thomas Lindgren. Onsdagen den 11 december kl. 13.15 i rum 311, hus 1, Polacksbacken, Computing Science Department, Uppsala University. Numeropärmen 96.152

Information: New Mailing List:

Numeropärmen 96.153

Populärföredrag för gymnasister

I serien matematikdagar för intresserade gymnasister och deras lärare talar tre Nadaforskare populärt tisdagen 10 december 1996 kl 12.30 - 15.00 i sal F2.

Örjan börjar med datorsimulering av hjärnan, sedan ska Viggo stava rätt utan ordlista och så avlutar Henrik med lite komplexitet.

Henrik Eriksson

Internationella Lärarutbyten HT 97

Den som är intresserad av lärarutbyte med något universitet främst i Europa kan kontakta mig angående ansökan. Ansökningstiden går ut 17/1-97. På Nada har hittills 3 lärare deltagit i denna verksamhet, 1 i England och 2 i Tyskland.

Lennart Edsberg

Guest Researcher of VIRGO

As mentioned previously, VIRGO is a research project funded by EU, primarily funding guest researchers in the field of visual-based navigation, for which I am project leader. Up to last of Feb. 1997, Dr. Antonis Argyros from. Univ. of Crete, and FORTH (Crete) will be working on robot navigation strategies and visual-based measurements of properties of flow.

Fredrik Bergholm

Licentiat-seminarium: Multiphase Computations in Geometrical Optics

Olof Runborg håller licentiat-seminarium under ovanstående rubrik fredagen den 13 dec. kl. 13.15 i sal E36 (Osquars backe 2, plan 3).


In this work we propose a new set of partial differential equations (PDEs) which can be seen as a generalization of the classical eikonal and transport equations, to allow for solutions with multiple phases. The traditional geometrical optics pair of equations suffer from the fact that the class of physically relevant solutions is limited. In particular, it does not include solutions with multiple phases, corresponding to crossing waves. Our objective has been to generalize these equations to accommodate solutions containing more than one phase. The new equations are based on the same high frequency approximation of the scalar wave equation as the eikonal and the transport equations. However, they also incorporate a finite superposition principle. The maximum allowed number of intersecting waves in the solution can be chosen arbitrarily, but a higher number means that a larger system of PDEs must be solved. The PDEs form a hyperbolic system of conservation laws with source terms. Although the equations are only weakly hyperbolic, and thus not well-posed in the strong sense, several examples show the viability of solving the equations numerically. The technique we use to capture multi-valued solutions is based on a closure assumption for a system of equations representing the moments.

CAS-seminarium: Mission Specification and Control for Multiagent Robotic Systems

Prof. Ronald Arkin, Georgia Inst. of Technology, håller CAS-seminarium under ovanstående rubrik på måndag (9 dec.) kl. 10.15-11.30 i sal Q24 (Q-huset, Osquldas väg 6, plan 2).


Ongoing research within the Mobile Robot Laboratory at Georgia Tech is studying several important issues involving multirobot teams. After first reviewing an earlier NSF-funded study regarding the role of communication in multiagent robotic systems, results in three current areas of DARPA funded research are presented:

In addition to testing these ideas with Denning Mobile Robots in our laboratory, the results of much of this research has also been demonstrated at ARPA's UGV Demo C in the summer of 1995. This includes successful demonstrations using our formation behaviors on 2 Lockheed-Martin HMMWVs for off-road navigation.

Henrik I Christensen

CAS-seminarium: Ecological Robotics: A Schema-theoretic Approach

Prof. Ronald Arkin, Georgia Inst. of Technology., håller CAS-seminarium under ovanstående rubrik på tisdag (10 dec.) kl. 10.15-11.30 i sal Q24 (Q-huset, Osquldas väg 6, plan 2).


The goals of this joint research project with ITAM in Mexico City are to provide an understanding and means by which fielded robotic systems are not competing with other agents that are more effective at their designated task; are successful competitors within the ecological system and capable of displacing less efficient agents; and are ecologically sensitive so that agent environment dynamics are well-modeled and as predictable as possible whenever new robotic technology is introduced. Initial studies on neuroscientifically derived schema models of the praying mantis are reported that are leading to both simulation studies and robotic implementations that can provide guidance to neuroscientists, ethologists, and roboticists alike.

Henrik I Christensen

Exjobbsseminarium i datalogi

Ett exjobbsseminarium i datalogi äger rum på tisdag (10 dec.) kl. 16.15- 18 i sal E1 (Osquars backe 2).

Clas Agneborg och Jacob Holm, T92 resp. T91, 12p: Simulering av teletrafiken från en företagsväxel. Arbetet är utfört vid Ericsson Business Networks, Nacka. Handledare: Magnus Andersson, examinator: Lars Kjelldahl.

Anders Furuhed, D91, 20p Användning av C++-kod i ett system för distribuerade objekt. Arbetet är utfört vid Trinity College, Dublin. Handledare: Viggo Kann, examinator: Stefan Arnborg.

Lars Pechan, D88, 12p. Algoritmer för skalning av digitalt lagrade bilder. Arbetet är utfört vid JOB systemintegration AB. Handledare: Staffan Romberger, examinator: Lars Kjelldahl.

Stina Leijonhufvud, D92, 20p. Utredning av en metodhandbok för analys och design av användargränssnitt. Arbetet är utfört vid Scala. Handledare och examinator: Kerstin Severinson-Eklundh. Opponent: Peter Nordvall.

Kerstin F.

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Senast ändrad 5 dec. 1996 <>