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A Computational Model for Bharata Natyam Choreography


Vol. 8 No. 7 October 2010 International Journal of Computer Science and Information Security

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									                                                            (IJCSIS) International Journal of Computer Science and Information Security,
                                                            Vol. 8, No. 7, October 2010

                           A Computational Model for Bharata Natyam Choreography
                   Sangeeta Jadhav, S.S Dempo College of Commerce and Economics, Panaji, Goa India. sangeetajadhav@yahoo.com
                                            Sasikumar, CDAC, Mumbai, India. the.little.sasi@gmail.com

     Abstract: Indian Classical dance has been the slowest to adopt technology and although choreography is mainly a domain of
     creativity, computers can help a lot to ease this especially for rhythmically oriented intricate footwork, Nritta and the
     complementary movements of other limbs of the body. The main objective of this paper is to identify and classify the various
     angalakshanas of Bharata Natyam. An angalakshanas in Bharata Natyam refers to classification of elementary body movements
     like head, eye, neck, hands and leg movements. The research aims at a well organised classification of the angalakshanas along
     with identification of various constraints on their co- occurrences and sequencing. The constraints may be physical, aesthetic or
     preferential and would be identified through literature study and machine learning from databases of existing dance repositories
     and training videos. The work will be useful to enhance the learning/teaching of Bharata Natyam (and other dance forms) and
     also for animated choreography.

 1. Introduction - To develop a computational model of                      Upanga are supposed to move in unison with Anga. Anga
 Bharata Natyam covering angalakshanas and talas (a                         lakshana is a classification of elementary body movements
 rhythmic cycle of beats with an ebb and flow of various                    which are as follows- Head movements–Shirobheda; Neck
 types of intonations resounded on a percussive instrument).                movements -Greevabheda; Eye movements -Drushtibheda;
 Any dance form can be conceptually decomposed into some                    Leg movements –Padabheda; Hand movements –
 constituent base movements involving specific body parts,                  Hastabheda. Some of them are as follows:
 and norms for combining them. The combinations are
 constrained by physical constraints, aesthetic constraints,
 preferential constraints, etc. Treatises like Natyashastra
 codify such constraints and rules in a human understandable
 form. This research attempts to model these in a
 computational framework, using practical experience and
 existing literature. This would help evolving better teaching
 programs, better understanding of the dance form, enhanced
 ability to compare one dance form to others in India and
 abroad, use ICT in composing and designing dance
 programmes, and so on.
 The basic methodology proposed would be to study and
 tabulate the various angalakshanas, relate them to tala – a beat
 cycle – to study constraints and preferences, and develop a
 machine          learning model which        can generate/critic
 movement sequences. We propose to use artificial
 intelligence techniques such as neural networks, constraint
 programming, evolutionary programming and heuristic
 search in this process.

1.2 Structure of Bharata Natyam: Bharata Natyam is one of
the most ancient of all the Indian Classical dance styles.
Although there is no formal notation available for the dance                While performing, a dancer can use one Angalakshana like
form, it is a highly formalized dance as described in ancient               only the eye for example for a beat or use all the
texts. This dance is known for its grace, purity, tenderness and            Angalakshanas e.g. eye, neck, head, legs, hands
sculpturesque poses. Bharata Natyam is based on the precepts of             simultaneously for the same beat. Of course, not all
among others - Bharata's Natyashastra and Nandikeshwara's                   combinations are physically possible. Some are aesthetically
Abhinayadarpana - to mention the most well known theorists of               not recommended. Similarly, the sequence of angalakshanas
the dance. From the moment the danseuse enters and until                    from one beat to next also has such constraints governing
dancer leaves the stage, dancer has to regulate their movements to          them. This is the focus of the research we discuss here.
musical accompaniment in strict accordance with the rules of
the dance form. There are two major aspects to this form of dance:          2. Related work in this area: Although many research papers
Nritta    (rhythmic       dance     movements)        and   Nritya          can be found dedicated to Western dance styles like ballet and
(representational dance). Although there is no clear                        foxtrot, very few can be found for Indian Classical Dance.
demarcation between the two this research will restrict itself to           here seem to be few studies related to creating computerized
Nritta or pure dance movements. Nritta is divided into Chari -              choreography for any Indian classical dance. However the
walking movement; Karna - balanced composition of hand                      following papers and articles are related to Indian classical
and leg movements; Angahara - different combination of                      dance with emphasis on animation: Soumyadeep Paul, et al,
Karna; Mandala - postures with hand gestures. The body limbs                [6] describes in their paper about an off-site coach who uses
are classified as: Anga (main body parts); Pratyanga (minor                 low band-width joint-motion data and can instruct students
limbs); and Upanga (features of the face). Pratyanga and                    who are even geographically far away. This application does

                                                                     231                               http://sites.google.com/site/ijcsis/
                                                                                                       ISSN 1947-5500
                                                          (IJCSIS) International Journal of Computer Science and Information Security,
                                                          Vol. 8, No. 7, October 2010

not require the user to wear any kind of equipment. Sumant                  (sometimes three or four in case of similar ones) to indicate a
Narayan Pattanaik [7] in his article has described the work                 position of that part for e.g. code starting with SH indicate
done at the National Centre for Software Technology, now                    Samyukta Hasta which is double hand movement and GB
CDAC in Mumbai on creating a computational modeling of                      indicate Greeva Bheda which is a neck movement and so on.
human body and movement for animating Bharata Natyam                        The various positions of a limb are given as a two character
dance.                                                                      code e.g. AH-pa indicates pataka from Asamyukta Hasta.
  2.1 Dance Notation                                                        Thus across time SH-an, SH-kat, SH-aw means double hand
                                                                            movements moving from one position to another position.
One of the problems involved in creating computational
                                                                            This enables us to define a dancer’s position at a particular
models for dance is that of notation. In the field of Western
                                                                            point in time as a vector giving the position code for each
Dances 'Labanotation' a system using symbols to write down
                                                                            limb. For example in following fig.
the movements of dancers, especially in a ballet has been
developed particularly following the research conducted at the
University of Frankfurt [9] and Ohio State University[9].
Using labanotation several software programs have been
developed such as LabanWriter[15], CALABRAN[13],
LabanPad[10&12],        Limelight[11]    and     LifeForms[14],
However most of these programs are useful mainly either for
notating and archiving dance or for animating dance.
Annemette P Karpen , Bharata Natyam dancer and
choreographer since 1977, presented a paper[16],
“Labanotation for Indian Dance” at the 11th European
conference for Modern South Asian studies, Amsterdam
University, July1990. In this she tried to solve the problem of
notation for Bharata Natyam by using Labanotation a notation
                                                                            This pose cane ne vectorised as follows:
used for Western dance. However the problem was not
                                                                          [SB, GB, DB, SH, PB].
completely resolved because of the many small movements of
                                                                          Across time, each element of the vector changes the code. A
Bharata Natyam; hence she tried to adapt Sutton Shorthand
Notation in which she added some extra signs for this purpose             sequence of vector represents a dance movement in time
although this was not completely systematized.                            duration. This structure will be used for further analysis and
  Thus Labanotation is not adequate for Bharata Natyam and                modeling.
  our proposed research focus however is totally different from            The next concern addressed was movement feasibility. As
  the work mentioned       above as it seeks to generate                  mentioned earlier this could be physical constraint ( sitting and
  permutations and combinations of angalakshanas, for a given             standing at same time or bending back and front or moving neck
  input beat, for which new algorithms may need to be                     side to side and looking straight at same time is not possible) ,
  developed. The idea of creating a new notation is not in the            dance theory base( hip and chest movements are not allowed ),
  purview of this research at present.                                    preferential etc.
                                                                          A physical constraint within a vector has been identified. The
 3. Proposed Computational Model: The overall objective,
 as mentioned earlier, is to build a computational model of a             restriction may arise more often not as a general restriction,
 dancer’s body limb movements across time in the Nritta                   but as applicable in certain positions e.g. if neck is in position
 context. We started with a study and analysis to identify the            3 at time t1 then in (t1+1) position 1 is not feasible.
 various distinct movements possible in Bharata Natyam of                 Identifying such constraints along with the applicable context
 various body parts such as eye, head, neck, hand, leg, etc. We           can be a hard task given the exponential number of
 have now identified a collection including:                              combinations possible. Not that while we expect most
 •       9 Head movements(Shirobheda);                                    constraints to be either at a particular time point or between
 •       1 Neck movement (Greevabheda);                                   two successive time points, it is possible to have constraints
 •       8 Eye movements(Drishtibheda);                                   across more than two time units also. We do not consider this
 •       39 Leg movements(Padabheda);                                     at present.
 •       Hand movements(Hastabheda):                                      We propose to collect many instances of possible dance
      14 single hand(asamyukta)                                           position vectors (henceforth dp vectors), have them labeled
      3 double hand (samyukta)                                            by human dance expert and use them to generate the
 Typically at any point in time, a dancer can choose for each
                                                                          knowledge base of such constraints. We have completed a
 body part one of these possibilities. Where there is no explicit
 movement, the default position can be considered. Based on               simple vector generator and further refinement and labeling
 experience, observation and literature we have identified                is in process.
 movement combinations which are either infeasible or                     These labeled instances will be used in a machine learning
 unusual. This is currently within one time unit (one                     program to build the model. Inductive learning, evolutionary
 count/beat/taal).                                                        programming and neural network model are under
 For formalizing the model, we have adopted a notation system             consideration at present. While a model like inductive
 as follows. We use the Sanskrit name for the Angalakshanas               learning can produce human understandable knowledge,
 as mentioned before; the first two letters of this name is used          compared to models like Neural Network, other aspects such
                                                                    232                              http://sites.google.com/site/ijcsis/
                                                                                                     ISSN 1947-5500
                                                           (IJCSIS) International Journal of Computer Science and Information Security,
                                                           Vol. 8, No. 7, October 2010

as quantity and quality of data and nature of data need to be                Dance And Choreography; an Intelligent Nondeterministic
also considered in making a selection.                                       Generator”, ACM, 2009 , 30-34, April
Among the current research challenges are formulations of                    [3] Tom Calvert, “Animating Dance”, ACM, 2007, May
an appropriate feature vector for learning algorithm, choice                 [4] Tom Calvert ,Lars Wilke , Rhonda Ryman and Ilene fox,
of learning algorithm, representation of context,                            “Applications of Computers to Dance”,IEEE,2005,6-12 ,July
identification of parameter outside the dp vector which may                  [5] James H Bradford and Paulette cote- Laurence,” An
influence the choices, dealing with variability among human                  Application of Artificial Intelligence to the choreography of
expert judgment etc.                                                         Dance”, Computers and the humanities,1995, 29, 233-240
The proposed tools to be studied viz. - trained neural                       [6] Soumyadeep Paul, Sudipta N. Sinha and Amitabha
networks; genetic algorithms and heuristic searches have                     Mukherjee, “Virtual              Kathakali: Gesture driven
been chosen for the study from among others because of the                   metamorphosis”, Centre for Robotics, IIT Kanpur,
computational complexity of the problem. The utility of                      http://www.iitk.ac.in/robotics/project_lists/gesture/kathakali/
artificial neural network models lies in the fact that they can              [7] Sumant Narayan Pattanaik ,"A Stylised Model for
be used to infer a function from observations. This is                       Animating Bharata Natyam, an Indian Classical Dance
particularly useful in applications where the complexity of                  Form" , Computers in art, design, and animation , John
the data or task makes the design of such a function by hand                 ansdown, Rae A. Earnshaw (eds.) Springer-verlag New York
impractical. A simple set of angalakshanas or elementary                     Inc., USA, 1989 .
body movements has following complexity: 9 Head movements;
4 Neck movements; 8 Eye movements; 39 Leg movements;                         [8]    Labanotation,      The     University       Of     Frankfurt,
Hand movements: 28 single hand and 23 double hand                            http://www.gotan.ch/labanotation.html
movements. For choreography of n beats for each of these
the permutation and combination will result in (7233408)^n
movement possibilities! The resulting database for any beat                  [10]http://user.unifrankfurt.de/~griesbec/CHOREOE.HTM
is huge and requires proper techniques for management of                     L#LabanPad
data too.
4. Current status of research: With a Java program,                          [12http://user.unifrankfurt.de/~griesbec/LABPDE.HTML
permutation and combination of all the Angalakshanas have                    [13] http://web.bham.ac.uk/calaban/frame.htm
been generated, without any constraints for a single beat and                [14]http://www.lifeforms.com/products/index.htm
the resulting output is more than 2 millions of dp vectors .
These constraints are related to those movements which are                   [15]Labanwriter,     The     Ohio     State    University,
either physically not possible to perform or aesthetically not               http=http://dance.osu.edu/3_research_gallery/Labanotation
good movements to look at. For example the leg movements                     _history.html
have 4 types: walking movements, leaps, circles and static                   [16]Annemette P Karpen’s website, http://www.klassisk-
postures. All 4 movements cannot be done at the same time                    indiskdans.dk/13bharata%20natyam_kathakali_odissi_kathak
by the performer and hence this is a physical constraint. An                 _dans_koebenhavn_klassisk%20indisk%20dans_kas
example of aesthetic constraint could be performing dance                    trupvej%2098%20a_indisk%20musikforening_chau.htm
by looking at one corner only or looking down; which is
never used for Nritta. Even after considering few such
constraints, the result has been reduced to few thousands and
needs further more methods to reduce the output to a
manageable state. The research idea is at its infancy yet.

 5. Conclusion: The tool developed could help in choreography. It
 can generate various permutations and combinations of
 Angalakshanas in Bharata Natyam by which many mundane tasks of
 a choreographer will be reduced. The choreographer shall not have
 to think which movements to give for Nritta, every time it occurs in
 a music number. This tool can quickly show an entire list of moves
 available for a particular beat hence voiding repetition of the
 choreographer’s favorite move again and again and thus will create
 unusual choreography. It can also be used as a tool in dance
 education by introducing students to a variety of new dance
 movements and allowing them therefore to explore new ways to
 expressively combine those movements.

 6. References
 [1] Scott de Lahunta,“The Future of Choreographic practice :the
 Choreographic Language Agent (CLA)”, 2009, February
 [2] Mario Nakazawa and Andrea Paezold-Ruehi , “Dancing ,

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