echo & narziss 1 submitted by Daniel Fischer in partial fulfillment of the requirements for the degree of Diplom-Mediengestalter to Bauhaus-Universität Weimar, Fakultät Medien Weimar, May 13, 2004 supervised by Hochschuldozent Ralf Homann Prof. Dr. rer. nat. Bernd Fröhlich 2 »When Narcissus died the pool of his pleasure changed from a cup of sweet waters into a cup of salt tears, and the Oreads came weeping through the woodland that they might sing to the pool and give it comfort. And when they saw the pool had changed from a cup of sweet waters into a cup of salt tears, they loosened the green tresses of their hair and cried to the pool and said, ›We do not wonder that you should mourn in this manner for Narcissus, so beautiful was he.‹ ›But was Narcissus beautiful?‹ said the pool. ›Who should know better than you?‹ answered the Oreads. ›Us did he ever pass by, but you he sought for, and would lie on your banks and look down at you, and in the mirror of your waters he would mirror his own beauty.‹ And the pool answered, ›But I loved Narcissus because, as he lay on my banks and looked down at me, in the mirror of his eyes I saw ever my own beauty mirrored.‹ « Oscar Wilde, ›The Disciple‹ 3 5.1.3. Forward.............................................................................32 Table of Contents 5.1.4. Backward...........................................................................33 1. Introduction.............................................................................................5 5.1.5. Contrast............................................................................34 2. Background..............................................................................................6 5.2. Binary Presence Image...............................................................34 2.1. Global Context..............................................................................6 5.2.1. Average/Difference/Threshold.......................................34 2.1.1. Computers, Video and Dance............................................7 5.2.2. Shadow.............................................................................35 2.1.2. Computer Vision................................................................7 5.2.3. Difference to known projection image..........................36 2.1.3. Open-Source/Free Software..............................................9 5.3. Further pixel-based analysis......................................................37 2.2. Local Influences...........................................................................9 5.3.1. Image Moments................................................................37 2.3. Personal Background..................................................................10 5.3.2. Motion History Image.....................................................38 2.4. This Paper.....................................................................................11 5.3.3. Edge Detection.................................................................38 3. Goals........................................................................................................12 5.4. Contour.......................................................................................39 3.1. General Goals...............................................................................12 5.4.1. Curvature.........................................................................40 3.2. Personal Expectations.................................................................12 5.4.2. Local maxima of absolute curvature.............................40 3.2.1. Make a concentrated effort..............................................12 5.5. Synthesis.....................................................................................42 3.2.2. Have a controlled situation.............................................12 5.5.1. cairographics....................................................................42 3.2.3. Advance the technology..................................................13 5.5.2. OpenGL and GdkPixbuf...................................................42 3.2.4. Flabbergast the audience.................................................13 5.5.3. Buffering in RAM.............................................................43 3.3. My current view on these goals..................................................13 5.6. Outlook........................................................................................43 4. Technology.............................................................................................14 6. Performance..........................................................................................44 4.1. GStreamer....................................................................................14 6.1. Theme..........................................................................................44 4.2. Overview......................................................................................15 6.1.1. Narrative...........................................................................44 4.3. The ›Pakt‹ framework.................................................................16 6.1.2. Interpretation..................................................................45 4.3.1. XML abstraction for the GObject model.........................17 6.1.3. Representation................................................................46 4.3.2. Modular integration of third-party libraries.................17 6.2. Realization..................................................................................47 4.3.3. Prototypical Access Clients.............................................18 6.2.1. Technical Setup...............................................................47 4.4. The ›Warsaw‹ library.................................................................20 6.2.2. Participants......................................................................48 4.4.1. Introduction....................................................................20 6.2.3. Dramaturgy.....................................................................48 4.4.2. Processing models (filter types).....................................22 7. Summary.................................................................................................51 4.4.3. Thruputs and Bypass......................................................24 7.1. A Generic Toolkit.........................................................................51 4.4.4. Data Types.......................................................................25 7.2. Improvisation and Performance...............................................52 4.4.5. Properties (filter parameters)........................................26 7.3. Freedom and Constraints...........................................................52 4.4.6. Components integrated or developed...........................26 7.4. Future Directions........................................................................53 5. Application............................................................................................30 8. References..............................................................................................54 5.1. Rectification.................................................................................31 8.1. Pakt/Warsaw dependencies........................................................54 5.1.1. Displacement Maps..........................................................31 8.2. References to books and papers................................................54 5.1.2. Calibration........................................................................31 8.3. Web Links....................................................................................55 4 1. Introduction and if we extend our technology we extend the possibilities of our work. In some ways, this is a project about Freedom. Within this contrast of freedom and constraints I Freedom, and what you make of it, has become a like to place my work. For this is the same antago- focal point of my studies of Media Arts and Design at nism as the everlasting battle of artistic expression Bauhaus-University Weimar. I was lucky enough to and technical possibility, of vision and realization. find an environment where I could freely seek for what it is that drives my work. I have not found it, Consequently, most of my work deals with the de- and hope I never will. Yet, I have learned how to velopment of new tools. With the advent of affordable move in such a free space, how to use it for my own computing power, the possibilities seem endless, no good and the good of others. I have learned how to matter which way you look or which goals you want use my talents, and how to extend my abilities, to achieve. These possibilities, though, are of a within a liberal, encouraging and changing environ- purely theoretical nature. What we can do with ment. today's software seems to have no relation to what we could do theoretically. This is why the practice of my At the same time, this project is about constraints, work has shifted more and more to programming, about external and internal forces that impose limits even while the goals I want to achieve remain of a upon that freedom. Time, for one part, seems to be dedicatedly artistic1 nature. the most forceful constraint. There's never enough of it, there's always so much that could have been done given enough time. The limits of the technology available to us is another forceful constraint limiting our work.