Page  187 ï~~Motographicon: a system for computer choreography Peter Rajka rajka@nada.kth.se Tamas Ungvary ungvary@ kacor.kth.se Royal Institute of Technology, Dept. of Speech Communication and Music Acoustics, KACOR (Kineto-Auditory Communication Research group) Abstract This demonstration paper describes the most essential features of MOTOGRAPHICON - a system for computer choreography - in relation to the development of a structure-oriented method for choreographic composition. A notation system is a fundamental prerequisite for any kind of structural approach and analytical conceptualization with some degree of generality. While the creation, performance and perceiving of movement structures is a hierarchical process, different notational systems are necessary for different levels of movement description and manipulation [Min-Yun, 901. The different notational systems, tools and applications in Motographicon are intended to respond to these demands. 1 Notation of Human Motion in Motographicon Motographicon [Rajka et al., 921 includes several movement notation systems, supported by different applications: Script Notation (MOVE data format), Function Notation and the Symbolic Notation. The Script Notation (MOVE) is the common language for data exchange between the different notations and presentation systems within Motographicon. The Function Notation (graphs) provides a clean parametric representation of movements on a basic level, suitable for manipulation and analysis of the separate parameters of each body part. The advantages of the Symbolic Notation are the possibilities to read and understand movements, combined with structural orientation for the building of higher level analytic concepts. 1.1 The Script Notation (MOVE) The MOVE data [Lundin, 921 is in pure text format with commands and arguments grouped together in manner similar to LISP. This data format is supported by a library of functions for reading, interpreting and writing such files. A basic movement command corresponds to a body part and the joint supporting the part. The command specifies the target position for a movement starting at the present time and a duration for that movement. This is synchronized by the present time timing commands. A sequence of commands can be grouped to define a named procedure. The procedure can then be used as a basic command with the difference that the parameters do not represent angles but durations and in some cases a modifier ("mirror"). The duration for procedure calls are given as a percentage of the notated durations in the procedure. The mirror parameters gives a left-right reversal of all movements in the procedure. The procedure definition capacity in MOVE makes it possible to build movement libraries. The libraries can contain frequently used positions, for instance the normal ballet positions, but also longer movement scripts such as jumps and walks, etc. For composition and notation of modem dance, a library of movement themes and shapes specific to this dance form can be built and then used to test different ways of combining these elements in space and time. A dance notated with procedures can be modified into a different style by using a different library of procedures. 1.2 Function Notation The trajectories of a movement occur between consecutive body positions placed in time, as defined in a MOVE file, generated by the Symbolic Notation Editor (MotoSymb) or written in a text editor. Since the body positions are described by angles, a sequence of movement is represented by a sequence of consecutive trajectories, i.e. by a set of functions. The Function Notation Editor (MotoFunc) provides an effective visual record both of the basic time-space structures of a movement and of the evolution shapes of the parameters and also offers visual correspondence between the two kinds of movement representation (Function Notation and Symbolic Notation) by using the same time representation and angular scale system. This concept allows the transformation of Symbolic Notation into Function Notation and vice versa. The Function Notation Editor supports drawing, manipulation and generation of new graphs as the difference, sum or ICMC Proceedings 1994 187 Interactive Performance

Page  188 ï~~average of existing ones. Functions can be assigned to bodyparts and movement parameters for generating or modifying MOVE files. These facilities allow the creation and analysis of low level movement structures with a high degree of generality. 1.3 Symbolic Movement Notation (on Basic and Complex Levels) The Symbolic Notation on its basic level describes the simultaneous changes of position in time for each active body part. The Symbolic Notation on a higher level is founded upon user-defined symbols, representing complex movement procedures. facilities and the internal data representations are highly dependent on the design and the graphics of the notation system used by the editor. The Symbolic Movement Notation Editor (MotoSymb, founded upon Rajka Movement Notation [Ungvary et al, 921) in the Motographicon system is an attempt to separate the movement data and its graphic representation as far it is possible. This concept facilitates a more autonomous treatment of the motion in itself within the program and data structures, which permits the development of more complex manipulative features. Another advantage of the above described concept, is the possibility to define new symb C 0 +-E.-C m0 - 0 E C 0 E a to a) 0 o 0 MIDI Command files I C,..MIDI commands 0(Keyboard etc) CCP[ Figure 1: The schematic representation of the internal communication structure of Motographicon/NUNTI US 1.3.1 Symbolic Notation on Basic Level The Symbolic Notation on its basic level is constructed to describe any type of human movement which can be represented in terms of changes of rotation angles and translations in a 3d space. This concept of movement representation provides a high degree of generality and reduces the number of symbol types. Some investigations into symbolic motion description and editing have resulted in some significant results, e.g. LabanWriter by Scott Sutherland [Jackson, 92] or the Benesh Notation Editor by Ryman and Beatty [Ryman, 901]. A basic function of all notation editors is that they can be used both to enter new notation sequences and to edit existing ones. In many cases the editor ols and connect them to movement structures on different levels, from single parameters to complex movement procedures. For this purpose a higher level symbolic editor (MotoProc) has been developed. 1.3.2 Symbolic Notation on Complex Level The Movement Procedure Editor (MotoProc) is intended to treat movement procedures (movement "macros" in MOVE data format) and to generate movement files, based on these procedures as the building blocks. A list containing the names of MOVE procedures appears on a menu, after the loading of a library file which stores the procedure definitions. In the score window the user can create and manipulate different shapes (complex Interactive Performance 188 ICMC Proceedings 1994

Page  189 ï~~symbols) and associate them with a procedure name, by selecting the name on the menu list. By resizing a shape, the actual duration of the associated procedure call will be evaluated. The duration of a procedure call indicates the performance time of the procedure as percent of its original duration. In case of a group composition, the library procedures can be called by different dancers with different timing, durations and mirroring. Working with MotoProc, the user only need click on the animation window to get an animated performance of the current score or to examine a single procedure. 2 Animation of Human Motion Anima II is a tool in Motographicon for visualization of human movements. It is not intended for rendering purposes, but to function as a tool for immediate checking of notated scores. However, Motographicon is able to translate MOVE files to be performed by LifeFormsTM [Gaudet et al, 89J which supports several rendering formats. 2.1 Anima II ANIMA II is founded upon a parametric animation concept. It is characterized by objects defined by a set of parameters at each consecutive time step. The animation program creates frames (images) based on the assigned rotation and translation values as they are defined on a MOVE file. In the time span of the assigned duration value any number of in-between frames will be generated, limited only by the drawing rate of the actual computer system. In Anima II the user works with scenes consisting of dancers, a simple floor and a background. It is possible to view several scenes simultaneously in different windows. The camera control feature allows the user to change the viewpoint in 3D, by moving the mouse in the scene window, without interrupting the movements. For the execution of a choreography a movement control panel provides play, stop, replay and speed functions. The speed control is scaled in metronome units. Anima II is able to receive MIDl-information - presently time code for synchronization with a sound file or a CD player, and MIDI commands which can affect optional variables in a dancer's MOVE data during the real time performance of the movements. 2.2 Life FormsTM and Motographicon Our research group has had an exchange of information with Tom Calvert and his research group at Simon Fraser University, which has resulted in a software link between our systems (Life FormsTMl and Motographicon). Life FormsTM is an advanced animation program based on facilities for interactive manipulation of outline figures. Movement sequences created in Motographicon can be converted to Life FormsTM format and - with some limitations - Life FormsTM files can be converted to MOVE format. 3 Summary The different notational systems, tools and applications in Motographicon are intended to solve the problems emerging from the complex and hierarchical nature of the process of creation of movement structures. Motographicon includes different notational systems and applications for different levels of movement description and manipulation. The real-time animation tools allow immediate visualization of human movements, synchronized with sound playback. Our experiments in applying Motographicon to more extensive choreographic works and in dance teaching constitute an effort to establish a new, structure-oriented composition technique in the art of choreography, closely related to the development of the multimedia arts. Acknowledgments The above paper is based on research and technical development carried out within the framework of the Transmedial Communication System NUNTIUS [Ungvary et al, 921 by the Kineto-Auditory Communication Research Group (KACOR), mainly at the Royal Institute of Technology, Stockholm, with the support of the Bank of Sweden Tercentenary Foundation, of the Swedish Research Council for Engineering Sciences, of the Council for the Renewal of Undergraduate Education and of the National College of Dance,in Sweden. References [Gaudet et al., 891 S.Gaudet, T.Calvert, S.Welman and C.Lee. Composition of multiple figure sequences for dance and animation. In New Advances in Computer Graphics, proceedings of Computer Graphics International, 1989 [Jackson, 921 Noami Jackson. Bits, Bytes & Tights. In Dance Connection, Sept/Oct, pp. 50-53, New York, 1992. [Lundin, 921 M.Lundin. MOVE 0: A language for computer representation / description of/basic human movements. Dance and Technology Conference, Proceedings, University of Wisconsin, 1992. [Min-Yun, 901 Zi Min-Yun The Evaluation Criteria of Movement Notation and its Application. In Proceedings of Second International Congress on Movement Notation, Honkong, pp. 206-216, 1990. [Rajka et al, 921 G.Carlsson, P.Lunden, M.Ludin, G.Nyman, P.Rajka, T. Ungvary. How to build a multi medial communication/creation system for music and human motion. MULTIMEDIA, Ed.t Kjelldahl, Springer Verlag, 1992. [Ryman 901 Rhonda Ryrnan. Creating Benesh Notation on a Macintosh Personal Computer. In Proceigs of Second International Congress on Movement Notation, H-onkong, pp. 165 -189, 1990. [Ungvary et al., 92] T.Ungvary, P.Rajka, S.Waters. Nunti us: A computer system for the interactive composition and analysis of music and dance. In Leonardo, Pergamon Press, Oxford. No.1, 1992. ICMC Proceedings 1994 189 Interactive Performance