| Feb. 2024 | Olimia, Slo, CVWW . |
| May 2023 | Prague, CZ, invited by Vaclav Hlavac. |
| Apr.2022 | Sevilla, E, invited by EU project. |
| Apr.2010 | Sevilla, Malaga, E, VACOP project, HOVACOP workshop. |
| Mar.2007 | Poitiers, F, invited Prof. at SIC. |
| July 2006 | Purdue Univ., USA, visit and presentations, invited by Zygmunt Pizlo. |
| June 2006 | Toronto, Can, visit and presentations, invited by Sven Dickinson. |
| May 2006 | Poitiers, F, visit and presentations, invited by Pascal Lienhardt. |
| Mar.2006 | Poitiers, F, PhD defense D. Arrivault. |
| Nov.2005 | Groningen, NL, invited talk: 'Hierarchies relating Topology and Geometry'. |
| Nov.2004 | Prag, CZ, invited talk: 'Hierarchies relating Topology and Geometry'. |
| Aug.2004 | Guilford, Surrey, GB, invited talk: 'Grouping and Segmentation in a hierarchy of graphs'. |
| Mar.2004 | Innsbruck, A, invited talk: 'Mustererkennung und Bildverarbeitung - ein faszinierendes Fachgebiet mit grossen Zukunftschancen'. |
| Dec.2002 | Venedig, I, invited talk: 'How to Construct and Optimize Graph Pyramids?'. |
| Mar-Aug.2001 | Sabbatical in France: at LERI, Reims, Luc Brun, seminar; at SIC, Poitiers, Pascal Lienhardt, Yves bertrand, Eric Andres, seminar; at LABRI, Bordeaux, Achille Braquelaire, seminar; INSA Lyon, Jean-Michel Jolion, seminar. |
| May 2000 | Lyon, F, ERASMUS intensive programme, presentation. |
| Sept.1999 | Bangalore, India, IAPR Executive meeting, participation as IAPR-treasurer. |
| June 1999 | Villach, A, visit and presentation at Fachhochschule. |
| Apr.1999 | Prague, CZ, CEEPUS Teacher's exchange. |
| Apr.1998 | Univ. of Surrey at Guilford, GB, ERASMUS Teacher's exchange. |
| Feb.1998 | Haifa, Israel, Review of Minerva's F. Ollendorf center. |
| July 1997 | Seattle, USA, visit and presentation on invitation by Prof. Robert M. Haralick. |
| April 1997 | Karlsruhe, G, visit and presentation on invitation by Prof. Kulisch. |
| Jan.1997 | Innsbruck, A, Guest professor, lecture. |
| Nov.1995 | Montpellier, F, visit and presentation invited by Profs. Ehoud Ahronovitz and Michel Habib. |
| Sept.1995 | Paderborn, G, visit and presentation invited by Prof. G. Hartmann. |
| Mar-Aug.95 | Sabbatical at ENS Lyon, F, Prof. Annick Montanvert, seminar. |
| July 1995 | CREATIS-INSA Lyon, F, visit and presentation, Prof. I. Magnin. |
| June 1995 | LIFIA Grenoble, F, visit and presentation, Prof. J. Crowley. |
| June 1995 | INRIA-ORION Sophia Antipolis, F, visit and presentation invited by Dr. Monique Thonnat. |
| May 1995 | TIMC Grenoble, F, visit. |
| April 1995 | seminar at INSA-Lyon, F, invited by Prof. J.-M. Jolion. |
| Feb. 1995 | Heidelberg, G, visit and seminar at Interdisziplinäres Zentrum für wissenschaftliches Rechnen, University Heidelberg, invited by Prof.B.Jähne. |
| July 1994 | Zürich, CH, visit at ETH Zürich invited by Prof. Kübler, presentation. |
| June 1994 | Amsterdem, NL, visit and presentation at the University of Amsterdam. |
| April 1994 | Grenoble, F, ERASMUS intensive programme, presentation. |
| Feb. 1994 | Palermo, I, visit and presentations at the University of Palermo on invitation by Prof. Di Gesu. |
| June 1993 | Holmdel, NJ, visit and presentation at AT&T, Bell Labs. |
| Feb. 1993 | Grenoble, France: ERASMUS teacher's exchange, presentation. |
| May 1991 | Moscow, USSR, visit at Academy of Sciences in Lvov, in Nishny Novgorod, and in Moscow, on invitation by Academy of Sciences. |
| June 1990 | College Park, MD, visit at CfAR. |
| Dec. 1989 | Stuttgart, G, visit at FhG-IPA, invited by Dr. Rueff, presentation. |
| April 1989 | Pittsburg, PE, visit at CMU on invitation of Prof. D. McKeown, presentation. |
| April 1989 | College Park, MD, visit at CfAR as part of a cooperation project. |
| Feb. 1988 | Budapest, Hungary, Computer and Automation Institute, visit. |
| Nov. 1987 | Konstanz, G, visit of Transfer Center Konstanz, Bilddatenverarbeitung, Prof. Massen. |
| Oct. 1987 | Moscow, USSR, Consulting. |
| Nov. 1986 | Budapest, Hungary, Central Research Instituts for Physics, presentation: Recent Projects and Activities at the Institute for Image Processing and Computer Graphics. |
| Dec. 1985 | Ottawa, Canada: invited Seminar at Canada Centre for Remote Sensing, two presentations: |
| a) Expert System + Computer Vision = Expert Vision System? | |
| b) Curves in Square Grid Pyramids. | |
| 1984 - 1985 | Research Associate (sabbatical) at the University of Maryland, Center for Automation Research, on invitation by Prof. A. Rosenfeld. |
| 1981 | ITC, Enscheede, Netherlands. |
| 1981 | Study trip through the US with presentation in Vicksburg. |