Working with body movements plays a central role in dance. The representations of body movements that dancers and choreographers work with has a large influence on their creative approach. Accordingly, these representations should be taken into account when digitising movement for archival and analysis. A particularly popular technology for translating movement into digital data is motion capture.
This document addresses artistic aspects of motion capture and places a focus on comparing computational representations of motion with the experiential and creative points of view of dancers. For a more technical description, an article is available that provides an overview over different sensor technologies for recording movement.
Motion capture detects the positions of specific points on the surface of a body and records how these positions change over time. By only recording changing positions while ignoring everything else, motion capture emphasizes motion over any other aspect of dance. This focus on motion provides an opportunity to reflect on and compare the role and meaning of movement from the perspectives of dance and computation. It is obvious that computing with its focus on abstraction, measurability and standardisation treats movement very differently than dance creation with its emphasis on qualitative, idiosyncratic and implicit aspects of movement. While these differences can give rise to misunderstandings and frictions in trans-disciplinary collaborations, they can also be embraced as fruitful sources of inspiration, especially with respect to the possibility of translating dance into digital forms of art.
Subjective and Computational Forms of Movement Representation
As part of the E2-Create project, a small study has been conducted to compare the movement representation that dancers work with with those employed by computational methods used for recording and analysing movement. For this purpose several dancers from the Staatstheater Mainz have been invited to improvise several solos while being motion captured. The motion capture has been conducted at Motionbank using a markerless optical system (Captury). For each solo, specific task instructions were given to the dancers that to help them focus on a specific aspect of body movement.
Body Poses
This task focuses on the role of poses in computation and dance. Motion capture operates as a of stop-motion technique in that it records sequences of poses with each pose corresponding to a static spatial distribution of body points. The illusion of movement is achieved by transitioning from one pose to the next. This understanding of poses aligns with other computational approaches of working with movement, such as the specification of specific poses as keyframes on a timeline and the interpolation of them. Accordingly, poses are a fundamental building block for recording and manipulating movement on a computer.
Instruction: Focus on poses rather than movement. Assume what you would consider non-daily poses such as poses in which limbs cross, or lower body limbs are higher than upper body limbs, or poses on the ground. Slowly move through these poses.
Movement Segments
This task places the focus on the role of movement segments in computation and dance. These segments are sometimes called movement units or elementary movements. Originally inspired from cognitive science, this basic units of movement are frequently used as means to modularise movement into building blocks that can be combined and concatenated to create longer movements.
Instruction: Improvise with a vocabulary of movements that gradually expands over time. Start with a single movement and repeat it a few times. Then keep adding movements, one at a time, and repeat each of them a few times. Over time, you have an increasingly large movement vocabulary available that you can choose from.
Quantitative Properties of Body Movement
This task deals with different ways of characterising movement. Motion capture provides a series of positional snapshots of body points. The movement qualities the dancers are asked to pay attention to represent characteristics that can be mathematically easily deduced from these positional snapshots.
Instruction: Improvise with three basic movement qualities. Vary one quality at a time from one extreme to the other. Work with your own interpretation of the chosen qualities. The qualities are: fast and slow, compact and expanded, isolated and combined.
Interviews
In addition to being motion captured, the dancers were also interviewed about how the interpreted the task instructions and what relevance the given task had to them.
Annotated versions of these interviews are available online.