Near Unison | Dan Dodds | Kinetica Art Fair 2013

Near Unison, my project exploring harmonographic traces is currently being shown at Kinetica Art Fair. The exhibition is in Ambika P3, the exhibition space attached to the University of Westminster on Marylebone Road. For more information on the exhibition, and details about tickets and opening times please visit the Kinetica Art Fair website.

Kinetica Art Fair - Near Unison

The exhibit features a prototype of the interactive harmonograph swings that could form part of the larger installation proposed for Burning Man Festival, along with casts of the harmonographic traces left in sand, and photographic work documenting the process.

“The 5th Kinetica Art Fair returns February 28th – March 3rd 2013 at Ambika P3, as one of London’s annual landmark art exhibitions and a permanent fixture in the Art Fair calendar, renowned as the UK’s only art fair dedicated to kinetic, robotic, sound, light, time-based and new media art.

Kinetica is hosting the work of over 45 galleries and art organisations nationally and internationally, with representatives from UK, France, Russia, USA, Poland, Holland, Spain, Italy, Hungary, Indonesia and Japan, collectively showing over 400 works of art.

A huge interactive light sculpture from Dutch artist Titia Ex will greet visitors as they enter the impressive Ambika P3 venue, and giant 3D sculptures from Holotronica will hover above the main space of the Fair. Other highlights include an exoskeleton hybrid of mananimal-machine by Christiann Zwanniken; a giant three dimensional zoetrope by Greg Barsamian; and a life-size ‘Galloping Horse’ made of light by Remi Brun”

Kinetica Art Fair Press Release

NEAR UNISON | Burning Man Festival | Black Rock Desert

NEAR UNISON is an installation that allows participants to visualize the harmonic relationships between them. Pairs of sit-on pendulum swings create several large scale harmonographs that scratch drawings onto the surface of the Black Rock Playa. The structure that holds these harmonographs is itself a physical representation of a harmonographic form that can be seen from a distance across the Black Rock Playa.

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The harmonograph was a 19th century machine that was invented to explore the geometry of sine waves. It was soon developed into a popular parlour room toy that was capable of producing beautiful and delicate drawings simply by mapping the relationship between two swinging pendulums. By changing the lengths of the pendulums, their wavelength and oscillating frequency are changed. When the ratio of these two frequencies is something complex like 35:73, there is no discernible pattern, but as soon as it hits a simple ratio such as 3:5 or 2:3 a clear pattern emerges. The relationship between visual harmony and mathematical ratio is exactly the same those found in musical harmonies: the ratios that produce beautiful drawings are the same as produce harmonious musical chords.

The title ‘NEAR UNISON’ is derived from the set of patterns that occur when the ratio of the two pendulums is very close to 1:1, as will occur when people of a similar weight are using the interactive harmonograph. It is expected that the patterns produced by these interactive harmonographs will describe, in an abstracted manner, the similarity of all human beings, while emphasizing the subtle differences between individuals.

The overall form of the structure is also derived from a 3D harmonographic surface with a ratio that is in this ‘near unison’ region. A plywood structure supports pipes that trace the harmonographic lines through space to create a delicately curved sculptural form that sits directly on the Playa. Suspended from this structure are a series of connected pendulums that participants are able to ride like swings. When they are are used, these pendulums trace harmonographic patterns onto the surface of Playa. The drawings that are created will map the interaction between pairs of participants.

For more infomation please visit

Harmonograph | Sand

A series of experiments tracing the movement of a freely oscillating pendulum in a layer of sand.

The pendulum’s centre of gravity is slightly off-centre, meaning that the the x and y components of its movement oscillate at very slightly different frequencies; the harmonic relationship between these frequencies causes remains constant as the amplitude decreases rapidly due to friction between the pendulum and the sand. The rate of decay of the amplitude can be controlled by the depth to when the pendulum penetrates the layer of sand.

Casts of these forms were made by pouring liquid plaster carefully over the sand once it had been held in place with a light coating of sprayed acrylic varnish.

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Harmonograph | Light

A series of long exposure photographs of a light on the end of a freely oscillating pendulum.

The pendulum’s centre of gravity is slightly off-centre, meaning that the x and y components of its movement oscillate at very slightly different frequencies; the harmonic relationship between these frequencies causes remains constant as the amplitude decreases due to friction between the pendulum and the air.

This set up is the most simple form of a harmonograph.

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3D Scan using photographs

Follow the link to the Autodesk 123D Viewer to view the native scan

Last year we saw Jack Munro making use of the DAVID 3D Laser Scanner software to scan his sand cast. Although home-made, this scanner requires a laser and about £300 of software.

Autodesk 123D Catch is a free piece of software that allows the user to create a 3D scan [imports into Rhino as a mesh] using only a set of normal photos. It is also available as an app for the iPhone meaning that you can take the photos and upload them at the same time. All of the image processing is done on Autodesk’s servers.

The video above uses the LinceoRV augmented reality software to show a comparison between the real object and its digital mesh counterpart.

The resolution depends on the number of photos, position of photos, background, lighting conditions, etc, but the scan depicted appears to have a resolution of about ±2mm on a 120mm wide object.

Augmented Reality Experiments

While trying to figure out useful ways to interact with some wire frame models of 3D Harmonographs, I started exploring some examples of augmented reality software that allows a 3D mesh model to be tracked to a physical marker. The two pieces of software experimented with were the AR Plugin for Autodesk Showcase and LinceoRV. Both are stand-alone render/presentation engines with an augmented reality mode.

I found the Showcase AR Plugin to work well with pre-recorded footage, but not accept my live webcam feed, and LinceoRV to work much better with the live feed, but be more limited on the types of marker that it accepted. Both pieces of software can handle multiple markers.

The software basically analyses a binary [black and white] feed from the film, recognises the marker symbols, and works out their distortion due to perspective. It then uses this distortion to accurately recreate the camera position in relation to the digital model.

Using the LinceoRV software could be an useful way to present/manipulate 3D models that are too challenging/costly to print.

Random Linear Growth – Hoopsnake

This example shows an animation of my ‘work-in-progress’ Grasshopper definition that uses Hoopsnake to recursively perform a ‘copy by mirror’ function on a geometric form. The two examples are based on a cube and a tetrahedron. The growth is linear; expanding by one module with each step. The position of each new module is determined by a new randomly selected face of the preceding module.

I would like to develop the definition so that it doesn’t self intersect, so any comments with ideas on how to achieve this would be appreciated!


TETRA is an installation that exploits the potential of mass participation to create a form that emerges from the interactions of hundreds of people with the construction system over a number of days.

Inspired by the work of R. Buckminster Fuller into space-packing polyhedra, it explores the unique three dimensional geometrical properties of the regular tetrahedron and related ‘tetrahelices’ [also known Boerdijk–Coxeter Helices]. Their geometries provide an invisible framework for the participants to work within. The modular tetrahedral construction system will be used by the participants to create forms that automatically diverge from one another.

These in turn provide spaces separated from other participants for individuals to pause and reflect on the location and nature of their surroundings. TETRA’s position out on the edge of Black Rock City means that once the structure starts to take shape, participants will be able to climb to positions that afford views across the city. Just as Burning Man asks participants to take a step back from the consumer capitalism, so TETRA allows participants to step back and view Black Rock City as a whole

TETRA is a modular kit of parts that are assembled by participants into a structure that changes form over the course of the festival. There are 160 modules, each one a tetrahedron made from four equilateral triangle shaped pieces of CNC cut exterior plywood. Each triangular face has a hole cut from its centre which, as well as decreasing the overall weight of the module, allows the modules to become rungs in a structure that can be climbed up, on, in and through.

The ply edges of the four plywood triangles are bound together with rope to ensure a joint that can transmit loads in tension from one sheet of ply to the adjacent two. There are pre-drilled re-enforced holes near each vertex to allow for adjacent modules to be bolted together with bolts and wing-nuts by participants.

Each module is designed for one person to carry while climbing sections of the structure already built. The participants are able to climb any of the structure that is already built, and bolt their new module onto the existing structure. Once built, participants are able to climb up, select a module to remove and move to another place. This means that the overall form is not set by the designer, but emerges from the collective desires of a large group of participants.

Because of the intrinsic geometry of tetrahedra and tetrahelices, the form will always contain diverging branches with inhabitable spaces within them.

Magnetic Tetrahedra

This animation shows a model made from modular magnetic tetrahedra. Each tetrahedron has a side length of 50mm, and contains four spherical neodymium magnets.

The tetrahedra build up according to rules that stem from their dihedral angle [angle between two faces]. The dihedral angle of a tetrahedron given by θ=arccos(1/3) [approx 70.5288°]. This means that five tetrahedra placed face to face around a single axis fall approximately 7.2° short of a full 360°. Because of this, the tetrahedra do not fill space, and instead form sections of helical structures called Boerdijk–Coxeter Helices [Named ‘Tetrahelices’ by Buckminster Fuller].

The magnets in the tetrahedra ensure that when placed by hand, they lock together face to face to form structures that completely follow these rules. When pushed just within range of the magnets of other tetrahedra, they exhibit self organising properties, but due to the power of the magnets, occasionally stick edge to edge or vertex to vertex instead of face to face.

Olympiapark München

These are photos from my trip to Munich Olympic Stadium, designed by Günter Behnisch and Frei Otto for the 1972 Olympic Games.

The trip included a walk up over the top of the lightweight cable-net roof structure of the main stadium.

The main drivers for the design of the event spaces were the desire to have a ‘green’ games, a compact games, and use the notion of transparency and light. The green element of the games is manifested in the fact that the stadium and other events spaces were set in a large expanse of newly created parkland [the site was previously an airfield related to the adjacent BMW factory]. The compact element came through in that the athletes were able to walk from their accommodation to all events except sailing.

The idea of transparency and light was born primarily out of two factors:

– A desire to have a set of venues that contrasted absolutely with the heavy monumental Nazi architecture of the 1936 Olympics

-The fact that the 1972 Olympics were the first to be broadcast using colour TV cameras, which took 8 seconds to adjust from shooting in sunlight to shooting in shade. The transparent roof of the stadium minimised the contrast between shaded and non-shaded areas, allowing continuous filming as the cameras panned around.

The structure itself is based on a cable net pulled into shape by cables attached to large hollow steel columns. These columns take so much compressive force that they have to rest on 35m deep concrete foundations. Protection from rain is the primary function of the roof over the stadium, and for this purpose it is covered in 4mm plexi-glass sheets.

As shown in the photos below, these are attached directly to the cable net grid by flexible neoprene connectors about 100mm long. The sheets are clamped along their edges to neoprene strips which create 100mm wide flexible movement joints connecting them to each other. The  plexi-glass sheets currently in use were put in during a refurbishment in 1994-99, and were taken up to the roof as 3m x 3m sheets which were then cut to size in-situ.

The thinness of the plexi-glass combined with the flexible movement joints allow the cladding to move as the structure moves with wind, snow and thermal expansion loading. The steel columns rest on rubber lined ball and socket joints, allowing them to move freely in every direction. The tops of the columns can move by up to around 1m with large snow loading. A demonstration of the flexible tensile nature of the roof came when we were told to jump up and down on the walkway running over it – the whole roof behaved like a trampoline, deflecting about 200-300mm vertically as we jumped.

The swimming pool is the only enclosed building that I photographed the interior of. Also on the site is the indoor arena. The interior space is defined by a tensile membrane that hangs about 1m below the cable net. The walls are made from curtain walling supported by exterior space-frames. The connection between the membrane roof and the curtain walling needs to be flexible enough to take up the movement of the cable net, and is provided by an ETFE cushion.