Use Case 2: Rare Dancing Knowledge
The dance case-study will focus on two specific use cases: contemporary dance and traditional dance. Dance is an immaterial art by essence, as it consists in the motion of the performer’s body. Dance can convey different messages according to the context, and focus on aesthetics or artistic aspects (contemporary dance, ballet dance), the cultural and social aspects (folk dances, traditional dances), a story telling (symbolic dances), spiritual meanings (whirling dervishes), etc. According to the type of dance, the precision of the motion and the way it is executed (referred to as "motion quality") will be of uppermost importance (contemporary dance), or will be secondary as only the functional motion will matter (most traditional dances). Some dances also come with additional accessories like costumes or instruments, which are part of the performance and need to be taken into account as they modify and influence the body motions. The level of detail of the motion that has to be taken into account in order to "capture" and to be able to learn a particular dance will thus greatly vary according to the specific study case. Hence, two scenarios are considered in the dance case study, addressing different levels of detail for motion capture (or mocap) and analysis:
1. Contemporary Dance: Contemporary dance is performed by professional dancers, who are in search of aesthetics and emotion expression in the way they dance. For this type of dance, we do not only want to capture the functional motions (turn, flip etc) but also the motion quality. Using optical motion capture will enable us to record with great accuracy the style of the dancers. The details of the motion quality will later be used to classify dancers and enable an intelligent database browsing of the recorded dances based on motion quality criterion. User centered perspectives will be developed building from interviews with contemporary choreographers. The motion quality analysis will also be used in the learning application to assess how an untrained dancer performing the same motions compares to the professional dancer.
Figure 1: Contemporary dance performed by professional dancers
2. Traditional Dances: This rare dancing knowledge consists of motion patterns that have to be reproduced in rhythm with the music and with the other performers, but where the details of how the motion is performed are less important than the motion itself. Traditional dances can be found all around the world and are strongly linked to local identity and culture. The know-how of the traditional dances survives at the local level through small groups of people who gather to learn, practice and preserve these traditional dances. The aim of this use case is to offer a learning platform open to any traditional dance, preserving and giving visibility to these ICH and enabling anybody to learn them without being physically present in the region where these dances are practiced. For these dances, the costumes or potential accessories are part of the performance and cannot be removed or modified to facilitate the recording. UMONS inertial mocap system along with the Microsoft Kinect 3D motion sensor will enable us to capture the performance with minimal disturbance. The style of traditional dances from different regions will also be studied and compared, along with the similarity of patterns present in different traditional dances. Depending on the degree of precision of the motion that has to be taken into account and to the constraints posed, different type of sensors will be investigated:
i) Optical Motion Capture: optical mocap is the most accurate motion capture technique, but it is also the most expensive and constraining one. The capture area is surrounded by cameras and reflective markers are taped to the performer’s body. These markers are tracked by the cameras and their position in the 3D space can be known on the sub-millimeter precision.
ii) Inertial Motion Capture: inertial sensors attached to the limbs can track the angles between the body segments. This mocap system is less accurate than optical mocap but it is very stable and does not need cameras or specific lighting conditions around the mocap area. Furthermore, as it is not linked to vision, it is the only system that will be able to capture the leg motion under a skirt.
iii) Depth Cameras: Depth cameras such as Microsoft Kinect can track the volume of a performer, and according to his clothes, a skeleton tracking can be extracted. This system is very cheap but the data captured are still noisy and some rotations or body parts cannot be recorded (especially when two dancers interact).
The three main goals of this case study are:
- Develop and study methods for capturing the ICH adapted to our two use cases, contemporary and traditional dances, and use them to enrich the resources of dance ICH available to the public.
- Develop innovative methods for the assessment of the motion quality, the study of the influence of personality and culture on the motion production, and tools for the comparison of dance motions among them (professional vs learner, traditional dances from different countries, personal style of different contemporary dancers, etc.).
- Produce new methods and interfaces to teach and learn dances, giving local dance groups a platform for preserving their knowledge at a broader level and to reach new learners that could not have been involved otherwise.