PixFlow is a generative artwork by LAb[au] based on a vector field determining the path of particles, pixels, shaping into flows as their density evolves. From the mutual influence between vectors and particles, changing their orientations as they meet, and calculating these changes according to two different number sets, integers and floating numbers, emerge due to rounding errors in between both sets an unsuspecting behaviour of particles shaping vertexes, migrating lines and turbulences by following the combinatory play of numbers. It is the use of an error in the set of a system to achieve an evolving and organic behaviour.

PixFlow #1 is an integrated artwork for the Casino Brussels restaurant created in 2005. The installation is constituted out of 11 plasma-screens driven by 11 networked computers forming a continuous strip of 13m.

PixFlow #2 is running on Lab[au]'s art console, a sculpture crafted in form of a T-shaped Plexiglas box, integrating 4 stripped screens and 4 networked computers.

PixFlow -Pixel

In digital imaging, a pixel (picture element) is the smallest unit of an image. Pixels are normally arranged in a regular 2-dimensional grid, and are represented by squares. The word pixel is based on the abbreviation "pix" for "pictures".

PixFlow - Flow

A flow is the volume of a fluid which passes through a given surface per unit of time.
The term of flow / fluid further expresses the quality of motion, to move or run smoothly with

unbroken continuity, as in the manner characteristic of a fluid, or as to proceed steadily and easily.

PixFlow / Vector field

Vector fields are used in physics to model and represent, for example, the speed and direction of a moving fluid through space, or the strength and direction of force, such as the magnetic or gravitational force, as it changes from point to point. A vector field is a construction in vector calculus which associates a vector to every point in a locally Euclidean space.

PixFlow - The generative system

PixFlow is a generative art work by LAb[au] constructed by computer software algorithms having as conceptual basis the use of systems as a method for making art, placing the creative act in the setting of such a system, its set of rules, which then can run autonomously.

PixFlow - Set of rules

At system launch, 1500 particles in form of pixels and the 5040 vectors, constituting the 90 x 56 matrix of the vector field, are initialised at random position (particles) and orientation (vectors) per screen. At a screen resolution of 1440 x 900 each vector of the field defines a cell (16x16 pixels) having a directional force indicated by a thin needle-like arrow in the back buffer of the rendering. The particles start to move at a constant speed of 5 pixels per frame, by a refresh rate of 25 frames per second, in the direction set by its own heading vector. When a particle enters a vector cell its direction turns towards the vector having a reflection angle of 15 degrees as maximum derivation. In return the orientation of a cell vector changes its orientation by 1 degree in the case the difference between the two angles is more than 30 degrees. This mutual influence in between moving particles and

vectors sets the main rule of the system. But the precision of the particle vector angle is defined by floating numbers whereas the cell vector ones only can turn in steps of integers which lead at the ponderation of the system to rounding errors giving the system less of a deterministic and more of an organic behaviour.

Consequently the conception of the generative system does not rely on any random set (except at launch initialisation), but builds its evolution on a recurrence of system errors occurring between two numerical systems, one defining the pixel movement angle; floating numbers, and the other the vector orientation; integers. The set of a system producing at each iteration errors is the starting point of the generative art work and form the backbone of a highly evolving and ever varying system.

The resulting fluid behaviour is visually reinforced by a trail the particles leave along their path. The trail is a buffer of the last 10 frames, an imprint of the last 10 positions of the moving particles, rendered with a decreasing alpha value ranging from the actual particles rendered at 100% opacity to its previous position rendered at 90% opacity ... This leads the moving particles leaving a 50 pixel long and progressively fading away trail. These trails on the screen are imaging the smooth movement of the particles shaping vortexes, migrating lines and turbulences.

The screen space

PixFlow is rendered in native screen resolution to achieve pixel-perfect rendering, juxtaposing particles being a sharp single point, a pixel, and the vector field being a fine geometric line to the grouping particles forming rather blurry veins due to density and the alpha blending on their trails.

In order to achieve the pixel-perfect and multi-screen rendering, one computer per used screen is needed, connected to one another through a local network. In this manner the

continuous horizontal space of the multi-screen version of PixFlow is achieved by the network synchronisation of particle position and vector orientations. Further on, the render plane of Pixflow constitutes vertically a continuous space where objects wrap around screen edges and particles drifting off the top edge of the screen reappear at the bottom following the same direction. This wrapping technique of the render plane is one of the specific electronic space constructs and has been used in video game classics such as 'asteroids' where the shuttle and asteroids never leave the surface of the screen but wrap from one screen edge to the other.

Following this horizontal and vertical synchronisation, networking and wrapping, one has to imagine the render plane of PixFlow as a torus allowing an uninterrupted evolution of the pixels over the flat screen space which can be constituted by one or several screens/computers such as in the 11-screen installation of the Casino Brussels or the four screen edition for LAb[au]'s generative art console. This spatial setting of the render plane allows the progression of the particles over the entire screen space leading occasionally to the congestion of particles on one single screen while the others are totally empty, or at other moments to smaller densifications spread all over the screen space. This spatial construct enhances the fluid character of PixFlow, setting the observer's eye in motion following even a single particle or catching the ephemeral shapes of grouped particles all over the screen space.