INTRODUCTION

Ballroom Dancing includes the Standard Dancesport dances: Waltz, Tango, Slow Foxtrot, Viennese Waltz and Quickstep. In Australia it also includes New Vogue dances. New Vogue dances are the folk dance of Australia. Like the Standard Dancesport dances, they are dances for a couple: usually a man and a woman, but unlike the Standard dances, they have prescribed choreography. A feature of these dances is the variety of holds used between partners. Many of the dances have been published as scores in the internationally recognised Labanotation, and the files for these scores published in machine-readable form using a Labanotation editor (LED). This article describes extensions to an interactive computer program for a PC which interprets automatically such a file, so producing animation of two figures dancing together.

Previous work has described the production of such animation from descriptions in an animation language (NUDES), and of the translation of Labanotation scores into movements of a single figure (LINTER) and the dancing couple (LINTEL).

Modifications to this latter computer program are described in this article which allow the figures to dance with contra-body-movement (CBM) and in contra-body-movemnt-position (CBMP) automatically from suitably notated Labanotation files. The main barrier to producing such movements has been the maintenance of the five points of contact between the two partners, given the difference in height (and leg length) of the partners, and the high heels worn by the woman, which make for different step lengths of the two partners.

The interactive computer program LINTEL also allows zoom in and out, rotation about the 3 axes, and shifting in 3D, while the figures are dancing, as well as variable speed and single frame forward and back animation.

It is planned to demonstrate live New Vogue dancing (requiring a clear floor area of 8x4 metres), and to demonstrate LINTEL on a PC in the presentation.

LABANOTATION

Many methods have been proposed for prescribing dances on paper, but one attaining international usage amongst amateur and professional dancers is Labanotation, which was invented by Rudolf Laban in the 1920's (Hutchinson, 1954). This is based a vertical staves, one set for each dancer, each consisting of three lines. Time nominally moves upward, with ticks on the central staff line indicating the beats. Symbols alongside the central line represent ground support, which in Ballroom Dancing indicate movements and postions of the feet and legs. Movements and positions of the arms and other parts of the body are represented by symbols on either side of the outer staff lines. Basic symbols represent positions and movements in 8 horizontal directions Three levels of height are indicated by the shading of the symbol. Other symbols are used as modifiers to show to what part of the body each basic symbol applies. Bow lines are used to indicate physical contact between parts of the body and between dancers. The notation can be used to describe any human movement to an arbitrary degree of precision. The lexicon of the full notation has over 1400 symbols.

LED in operation, showing the start of the Balmoral Blues in CBM

LED

A simple editor, LED, has been written (Hunt et al, 1979) to write scores involving a basic subset of just over 100 symbols of Labanotation. This has been used to notate the New Vogue dances commonly used Australian Dancesport competions. The data files produced by this editor are simple: they are ASCII files with one line per Labanotation symbol. Each line records the type of symbol, its direction, its x and y coordinates on the score, its height and width, and its shading.

LINTEL

This is a program that generates animation of one or two animated humanoid figures doing the movements prescribed in a Labanotation score generated using LED. The notation is first translated into a script file for the NUDES animation system, (Herbison-Evans, 1979) and this is then reread and animated using OpenGl. The program allows the user to zoom in or out, pan in three directions, rotate in three dimensions, freeze, advance single frames forward and back, and speed or slow up the movement. This latter can be done by simply changing the number of polygonal facets used to approximate each ellipsoid.

Locomotive steps in each of the eight directions of the basic Laban symbols are generated by separate routines in LINTEL. These generate the stylised movements used in ballroom dancing, which keep the torso over the moving foot, which in turn inhibit partners from treading on each others' feet. Also the step is defined from an open position of the feet to the next open position, in-keeping with the ballroom notion of 'foot pressure' during a step. A NUDES movment subroutine, called "dance", is produced by LINTEL from the LED file, and this is appended to a prewritten file NUDES script (lintel.n) which contains the definitions of the two dancing figures, the dance floor, and the standard holds and movements.

CLOSED BALLROOM HOLD

In this hold, the partners face each other directly. The hold requires the maintenance of five points of contact between the partners while they are dancing. These consist of three hand contacts:

1. the man's left hand holding the woman's right hand,

2. the woman's left hand resting on the top of the man's right upper arm (behind the arm in the Tango),

3. the man's right hand placed on the left shoulder blade on the back of the woman.

In addition to these 3 hand contacts, there are two more areas of contact:

4. the woman's left elbow rests on the man's right elbow,

5. the right area of the chest of each partner touches that of the other.

However with the approximate nature of the notation used for these examples, these latter two contacts were not notated, being subsumed under a prior knowledge of the dance style.

CONTRA-BODY-MOVEMENT

CBM is required for the maintenance of the five points of contact between partners during a turn. Each partner can only turn over their own standing foot, so to maintain torso contact which maintains aesthetic shoulder lines, their torsos must twist relative to their hips to continually face their partner during the turn. CBM may also be seen in the New Vogue Dances. In the Balmoral Blues: in bars 1, 2, 5 and 6: the partners face each other in double hold, facing wall and centre, while travelling at right angles to this along and against line-of-dance. In Labanotation, CBM can be indicated as a rotation sign in a column assigned to the the chest in the chest. The amount of rotation is indicated as usual by the pin in the rotation sign. The rotation sign and overlapping pin in the chest column are used by LINTEL to generate an appropriate twist in the chest. The cancellation sign in the chest column is used by LINTEL as a signal to undo the twist of the chest.

LED in operation, showing the start of the Barclay Blues with CBMP in bars 2 and 3

CONTRA-BODY-MOVEMENT-POSITION

This is locomotion of the body in a direction different from that in which the hips are pointing, as distinct from CBM which is locomotion in a direction different from the direction in which the chest is pointing. The direction in which the pelvis is facing determines the direction of travel in CBM, and so angles of the legs during locomotion may be referenced to the pelvis, as in normal travel. In CBMP, the pelvis is also twisted relative to the direction of travel, so a different reference is required for the angles of the legs. This must be a spatial reference oriented in the direction of locomotion. Extra reference ellipsoids have been added to the dance floor in the auxillary file lintel.n. When LINTEL encounters an area symbol with a pin in it, it orients the reference ellipsoid in the direction of the pin and thence forward uses that as a reference for the leg angles in the leg articulations of locomotion. As the man and woman partners often travel in different directions (eg the man travels forward and the woman backward) each has to have their own reference ellipsoid. The body-stance cancellation sign in the notation is used to return leg angle references to a figure's pelvis.

CONCLUSION

The modified LINTEL program now allows such basic movements as the Feather Step in the Slow Foxtrot, and the Weave in the Waltz to be interpreted accurately in the animation from Labanoation of these dances. The modified LINTEL program, lintel.n file, and the LED labanotation files have been made freely available on the web, so allowing anyone in any part of the world to see, appreciate, and learn the the Australian New Vogue Dances that are so much a part of the Australian heritage.

ACKNOWLEDGEMENTS

Many thanks are due to the late Phillipa Cullen who inspired this this work, to generations of students who each solved many pieces of the puzzle involved in this project, to the tolerant and kind staff at the many Universities who have hosted the development of this work on their computers, most recently to Kevin Suffern and Stephen Gowing at the University of Technology, Sydney, for their support and encouragement, and to Ron Chambers of Conroe Texas who designed and implemented the interactive environment and animation output, and who led the way to finally putting music to the animation to make it an artistic experience.

REFERENCES

Boyd, N. (1984a)
New Vogue Sequence Dancing, 165 Bobbin Head Road, Turramurra, NSW, Australia, Revised Edition.

Boyd, N. (1984b)
English Old Time Sequence Dancing Guide, 165 Bobbin Head Road, Turramurra, NSW, Australia.

Buckdale, R.S. (1983)
"Normal Feet for Dancing Ellipsoids", Proceedings Graphics83 (ed.: H. Hvistendahl), Sydney, pp. 71-76.

Herbison-Evans, D. (1979)
"A Human Movement Language for Computer Animation", Language Design and Programming Methodology (ed.: J. Tobias), Springer-Verlag, pp. 117-128.

Hesketh, R. (1989)
Revised Technique of the Thirteen New Vogue Championship Dances, Clayton Dance Centre, 296 Spring Road, Dingley, Victoria 3172, Australia.

Hunt, F.E.S., Politis, G., and Herbison-Evans, D. (1989)
An Interactive Graphical Editor for Labanotation, Basser Department of Computer Science, Technical Report 343, University of Sydney.

Hutchinson, A. (1954)
Labanotation: The System for Recording Movement, Theatre Arts Books, New York.