Planar  is an audiovisual installation that unveils the sounds of Coimbra, Portugal, through a set of floating beings that randomly move over the city and listen to nearby sounds. The audience follows this journey, from an aerial perspective, visualising these beings floating over a dynamic illustration of the city.


The result is an ever-changing audiovisual composition that is shown through two video projections in two opposite walls and heard through four speakers positioned in the corners of the room and oriented towards its centre. This audiovisual composition is created by a generative computer system that is based on two complementary modules: one that generates the visual part, implemented in Java with the open-source library Processing, and another that generates the audio part, implemented in Max/MSP.



The module that generates the visual part implements swarm algorithms to simulate thousands of moving beings responsible for creating an abstract representation of the city of Coimbra and exploring the resulting representation by flying over it.


The representation of the city consists in drawing the paths of the city and the Mondego river, which crosses the city. To represent the city paths, we implemented a type of beings that are attracted by an energy map that represents the most frequent paths made by people in the city. To represent the river, we implemented another type of beings that move along the river area. This movement is determined according to a predefined force field with small variations, which are caused by random Perlin noise. These two kinds of beings are drawn using semi-transparent circles that leave trails as they move (grey for the paths and blueish for the river). This approach creates a unique but recognisable illustration of the city of Coimbra that emerges from the simulation of thousands of these beings.


The beings that fly over the city illustration are controlled by a flocking algorithm to exhibit a behaviour that resembles a flock of birds. These particles, which are drawn with white circles, move randomly over the city and, this way, overfly the different soundscapes of it. Each soundscape is represented on the map by a shining yellow circle that changes its size according to its proximity to the flying beings. The list of sounds and their data, including their coordinates, is dynamically fetched from a remote server. This way, we can easily change the sounds of the installation, e.g. we can record new sounds and remotely insert them into the installation at any time.


The module that produces the sound is structured with an audio queue of 10 files, where 10 sounds can be played simultaneously to create a flowing composition. Different soundscapes emerge and fade depending on the path of flying beings, whose proximity with each sound positioned in the map is continuously received from the visual module. Both modules are then in constant communication, with the visuals controlling the auditory composition, dynamically updating the queue of sounds composing the overall soundscape. The value of proximity received defines three parameters: the index of sounds within the flying beings’ reach, and the loudness and delay values for each sound. The loudness, as the gain that defines the scale applied to the signal, is in direct proportion to the proximity value: the bigger the proximity is (the sound is closer), the louder the sound is played. The delay value, as the time interval between the original signal and its repetition, has the same relation, with the delay time diminishing with how close the sound is and the proximity increases.


The sounds that can be discovered with Planar  were recorded by Aglaíze Damasceno, Luís Antero, Mariana Seiça and Pedro Martins.




We would like to thank Convento São Francisco / Câmara Municipal de Coimbra, Jazz ao Centro Clube, Centre for Informatics and Systems of University of Coimbra, Department of Informatics Engineering of the University of Coimbra and all those who supported this work.