Materialization of Motions: Tangible Representation of Dance
Movements for Learning and Archiving
Mose Sakashita

Kenta Suzuki

University of Tsukuba
mose.sakashita@gmail.com

Kazuki Takazawa

University of Tsukuba
kawahara@ai.iit.tsukuba.ac.jp

Yoichi Ochiai

University of Tsukuba
1220kazu1412@gmail.com(a)Keisuke Kawahara

University of Tsukuba
Ikuzus.atnek.0626@gmail.com

University of Tsukuba
wizard@slis.tsukuba.ac.jp

(b)

(c)

Figure 1: (a) Design method for learning choreography. (b) Tangible representation of the choreography. (c) Zoetrope methods
to render 3D animation of body movements.

ABSTRACT1

We propose a method to learn and archive dance movements by fabricating tangible three-dimensional (3D) human forms. We analyze
the pattern of the tempo and rhythm of a music piece and fabricate
the shape of a 3D body based on the motions of the dance performer
by using a 3D printer. For the implementation, we employ a depth
camera to capture 3D information of a dance movement. Appropriate movements are extracted from the file at every constant tempo
by analyzing the tempo of the music piece played while the dance isperformed. The 3D printer enables tangible modeling of the dancemovements.

There has been a focus on studies and projects that combine danceand technology. For example, the project named Lighting Choreographer [Fujimoto et al. 2011] is an LED performance system that
expands the expression capability of the human body. Many ofthese studies on dance expression aim to extend a physical expression. In the research on choreography itself, it is common to use a
two-dimensional display.
Capturing and saving videos using a general camera is the mostcommon method for storing information that can be used for practicing and learning dance; this method is also used for live music.
(Figure 2) However, these records are composed of two-dimensional
information and three-dimensional information such as spatial information is lost. Spatial information is important while recording
dance movements because the positions of hands and feet are important for learning choreography; however, without this information,
it becomes difficult to understand the choreography in detail fromCCS CONCEPTS•General and reference →Design; Performance;

KEYWORDS
dance, choreography, archive, tangible

INTRODUCTION

ACM Reference format:
Mose Sakashita, Kenta Suzuki, Keisuke Kawahara, Kazuki Takazawa, and YoichiOchiai. 2017. Materialization of Motions: Tangible Representation of Dance
Movements for Learning and Archiving. In Proceedings of SIGGRAPH ’17
Studio, Los Angeles, CA, USA, July 30 - August 03, 2017, 2 pages.
DOI: http://dx.doi.org/10.1145/3084863.3084869

SIGGRAPH ’17 Studio, Los Angeles, CA, USA© 2017 Copyright held by the owner/author(s). This is the author’s version of the work.
It is posted here for your personal use. Not for redistribution. The definitive Versionof Record was published in Proceedings of SIGGRAPH ’17 Studio, July 30 - August 03,
2017, http://dx.doi.org/http://dx.doi.org/10.1145/3084863.3084869.

Figure 2: Previous methods for learning or archiving dancemovements.

SIGGRAPH ’17 Studio, July 30 - August 03, 2017, Los Angeles, CA, USAa three-dimensional point of view. It is possible to use a free viewpoint video; however, it is not suited for general users because ofproblems such as its display size and the necessity to input specificparameters constantly for varying the point of view.
If saving tangible three-dimensional information of dance movements can be made possible, learning and archiving these movements will become possible. Moreover, it can be helpful for blindpeople in addition to other dancers.
In this study, we acquire three-dimensional information of aperformer’s dance movements using a Kinect sensor and save it
as a motion file. Appropriate movements are extracted from thefile at every constant tempo by analyzing the tempo of a musicpiece played while the dance is performed. The 3D printer enables
tangible modeling of the dance motions.

2M. Sakashita et al.
common to choreograph a dance to the tempo of a music piece.
Therefore, instead of analyzing the image or depth information
itself, we analyze the tempo of the music piece and extract dance
movements based on the relationship between the movements andthe tempo.

DESIGNWe propose a new method to learn and archive choreography
through tangible 3D representation. Most people who want toenhance their dancing skills use movies or two-dimensional (2D)
drawings. The merits of 3D fabricated choreography are as follows.
(Figure 3)
First, the dancing postures are tangible. Therefore, users cantouch and confirm the position of the body parts such as hands
and feet. Moreover, blind people cannot obtain any information
about these positions through two-dimensional displays; therefore,
they feel uncomfortable when learning dance because someone
will need to physically move their body parts by touching them forthem to understand the postures. However, if they use 3D tangible
representations, then they can touch and grasp these positions ofbody parts.
Second, users have a 3D point of view of the dance postures,
which enables them to see these dance postures from any point ofview, which is not possible in case of 2D videos.
Finally, users can change the position of 3D object by direct
hand manipulation. This can be useful for choreographers when
considering choreography, formation, or structure.
There are mainly two ways to implement tangible representations for dance forms. One is used to put the motion postures on aplate in a certain order. (Figure 1 (a)) The other is zoetrope methods that can be used to render 3D animation of body movements.
(Figure 1 (b), (c)) In the former, there may be a lack of movements
in some frames; however, it can handle and put several movements
together. The latter has frames that are enough to render an animation of the choreography and users can understand the transitionsof dancing postures.
When outputting three-dimensional models, appropriate movements should be selected. For learning choreography, the selectionof the 3D-models is important. Specific movements like walking or
swimming can be detected and extracted more accurately since thepatterns of these movements have been recognized to some extent.
Some methods proposed for detecting movements use image
processing and depth information captured by a depth camera suchas a Kinect sensor. [Presti and Cascia 2016]
However, in the case of dance, there are various kinds of movements that are complicated. Accordingly, we focus on the processthat choreographers follow while choreographing a dance. It is

Figure 3: (up) Tangibility of the posture during dance.
(down) Ability to change the position of the 3D object. (right)
A 3D point of view.

3IMPLEMENTATION

Figure 4 shows our implementation, where we use a Kinect camera
to record the dance movements. We acquire the x, y, z positions ofeach joint detected by the Kinect Camera. The position information
is saved as a motion file with BVH format (30 FPS). The motion filecontains the definition of the hierarchy of 20 joints in a header androtation angles in every frame.
We analyze the tempo of the music piece played while the danceis performed for selecting the frames from the motion file. These
selected frames are printed by a 3D printer.

Kinect Camera

Extraction of motionsby tempo

Figure 4: Extraction of dance motions and printing tangible
3D models.

REFERENCES
Minoru Fujimoto, Fujita Naotaka, Tsutomu Terada, and Masahiko Tsukamoto. 2011.
Lighting Choreographer: An LED Control System for Dance Performances. In
Proceedings of the 13th International Conference on Ubiquitous Computing (UbiComp’11). ACM, New York, NY, USA, 613–614. DOI:http://dx.doi.org/10.1145/2030112.
2030240
Liliana Lo Presti and Marco La Cascia. 2016. 3D skeleton-based human action
classification: A survey. Pattern Recognition 53 (2016), 130 – 147. DOI:http://dx.doi.org/10.1016/j.patcog.2015.11.019