ADS:AJournal Week 05

Carl Madsen 357577

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After our analysis on the matrix of definitions in Grasshop-per and looking into the perspective differences created by overlapping surfaces and their potential to satisfy our design intent, we deemed them very similar to a moiré pat-tern.

A moiré pattern is an interference pattern that is cre-ated when two or more grids of lines (be them curved or straight) are overlaid in a non-regular fashion. This can be achieved through different shapes of lines (for example, a grid of circles overlapping a grid of straight lines), different mesh sizes or the rotation of one of the grids. The pattern is created at the intersections of the lines, where they appear thicker due to the higher density in the area. Such intersec-tions form patterns with neighbouring intersections, creat-ing a virtual line through the grids. The moiré effect (which creates the patterns) is typically an undesired effect of digitally created or altered images, but can also be used to advantages; it can be both a positive and negative effect, crafted or unwanted.

Seemingly merely a visual phenomenon created by the jux-taposition of two patterned elements, a fair amount of math-ematics is involved (differing throughout the shapes being patterned), reflecting the iconic direction approach we are looking to achieve with our design. Although the effect is visible on two unmoving grids, its more interesting qualities come from one or both of those two grids moving. However, with spacing between the two patterns, the eye moving shifts the panels relative to the viewer, recreating the effect on a still structure. This allows for a dynamic moiré pattern to be structured into the construction, changing the pat-tern it produces as the perspective differs (through both the relative speed and location of the viewer to the sculpture), resulting in a sculpture that is fast, directive, dynamic and experiential in design.

One important factor to note is that if there is to be a space between the two grid elements that form the moiré pattern, then the perspective of the viewer could potentially change the initial pattern. That is, the lines further away from the viewer would appear smaller due to them being further away, when in reality they are actually the same size as the ones closer to the viewer. This could change the pattern away from what is desired, unless it is duly accounted for.

thick lines into thick lines

basic open/close, like shutters

same width = full open, full close

thin lines into thick lines

semi close/semi open

never fully closed, never fully open, thinner lines moving between thicker

To start our experimentations with moiré patterning, we again instituted a breadth approach by creating a matrix of patterns that showcased some basic elements and how they interact with each other through changing variables. We didn’t just look at the shapes of the interacting lines, but also the thickness, angle and how far apart they were spaced. Once again we selected certain resulting patterns that both satisfied and avoided our design intent, critiquing them for further investiga-tion.

thin spaced lines into thick lines

same as thin into thick, but with inter-mittent breaks

thin spaced lines into thin spaced lines

open/close but with a large amount of time spent open as gap is larger relative to line thickness

thick lines into thick circles

creates a repeat-ing “opening” sector pattern perpendicular to the interfering lines

thin lines into thick circles

same deal, but pattern is much less pronounced as there is always a gap between the two geom-etries

15 degree thick lines into thick circles

same as first circle pattern, but a bit slower as lines take longer to be placed in the same spot (at same horizontal speed)

45 degree thick lines into thick circles

same same but slower once again

thick circles into thick circles

creates “opening” pat-tern in centre, rever-berates around entire combined geometry

thin circles into thck circles

“opening” pattern not visible, but shapes made from the gaps are very pronounced

thin circles into thin circles

same as first but hyper mode (faster, more, etc)

thin spaced circles into thin spaced circles

same deal with lines, still there but little inter-ference

128 line radial into same

crazy intricate pat-terns all over the shop

64 line radial into same

less patterns, but clearer

32 line radial into same

again less patterns, too many to be pro-nounced it seems

thin spaced circle into 16 line radial

some patterning, trumped by the dif-ference in geometries

Our initial generalised views were that lines that were simi-lar (but not necessarily an exact) thickness and distance apart seemed to produce more pronounced patterns within themselves, whilst lines that were exceedingly different thicknesses and distances apart had patterns that were very vague and hardly noticeable; on a high-speed high-way these light patterns would be overlooked and lost.

Rotation of lines into linesThe rotation of a set of lines into a similar set of lines shows the shrinking of the moiré lines into themselves as the angle of rotation between the grids increases (or the stretching of lines as the angle decreases). Although an interesting con-cept, the rotation of one grid without the other cannot be plausibly achieved in a static structure.

Lines into circlesThe introduction of a set of lines into a set of circles cre-ates a very interesting opening/closing effect that runs horizontally against the vertical lines, matching the flow of the highway. The speed at which the moiré lines open and close is determined by the speed at which the grids pass each other (represented by the speed at which the motorist travels).

Lines into linesThe movement of lines between lines created a very sim-plistic shutter-like opening and closing, which we deter-mined to although have relevance to the vectorial (cre-ated by speed and direction) qualities we were looking to achieve, its pattern was too basic and uninteresting to be developed beyond that.

Radials in generalLines arranged in a radial fashion superimposing on each other produced very intricate and omnidirectional curves in their boundaries, but this effect was overshadowed by the extreme clutter that developed at their centres. This clutter looks out of place in relation to the cleanliness of the sur-rounding ellipses to the point where it almost overshadows the moiré pattern created, resulting in a very undesirable connection.

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Based on the horizontal directional and easily distinguishable patterning qualities of the moiré effect created by the juxtaposition of a group of circles of varying radii with a grid of lines moving into them, we decided to have a more in-depth look at why this particular effect is created, and what the altering of variables within it pro-duces, finding some very interesting.

Based on a pre-existing paper Research on the Moiré fringes formed by circular and linear grating (Chen et al 2011), we discerned that the spacing of the lines played an important role in the moiré patterning visible between circles and lines. A succinct summary of the paper is the focus on two variables, P and a, where P is the distance between the circles and a is the distance between the parallel lines (summarised visually below).

Three distinct shapes were realised when changing the variable P (the distance between the parallel lines) against a static a. When the ratio P/a was greater than 1 (that is, when P > a), ellipses formed horizontally along the grids. When the ratio P/a was equal to 1 (that is, when P = a), parabolas formed, focusing to the centre of the circle. When the ratio P/a was less than 1 (that is, when P < a), hyperbolas formed, focusing to the centre of the circle. However, when the ratio P/a became too far away from 1, the patterns became difficult to distinguish, resulting in the need to care for the distances. This radical change in moiré patterning based solely on the distance between parallel lines prompted us to develop a parametric defini-tion in Rhino3D and Grasshopper that would allow us greater control over the vari-ables involved and the outcomes produced.

The definition we created in Grasshopper had six useful variables: P, the distance between the centres of the parallel lines, a, the distance between the centres of the circular lines, the thickness of the parallel lines, the thickness of the circular lines, the number of parallel lines and the number of circular lines. This enabled us to quickly test a large number of various iterations of the created patterns in real time by merely moving a slider.

On reflection of the potential issue (brought up in the introduction to the moiré ef-fect) that due to the viewer’s distance from each grid of lines they would see a dif-ferent pattern than what was intended on a flat surface, our experimentation with the moiré grasshopper definition presented an exceptionally exciting solution. We noticed that as the parallel lines became closer together (that is, as P decreased); the moiré pattern would quickly turn from ellipses into parabolas. However, with calculated spacing between the parallel lines and the circular lines, the viewer’s perspective of how many parallel lines were attributed to how many circular lines would be relative to their position. Somebody standing on the side of the parallel lines would see many circular lines for every parallel line, as the circular lines would be further away, appearing smaller to the viewer in relation to the parallel lines. However, somebody standing on the side of the circular lines would see the op-posite; more parallel lines for every circular line. With sensitive variables such as P and a, this effect compounds into a viewer on the circular side seeing hyperbolas, whilst at the same time a viewer on the parallel line side seeing ellipses. The way these two moiré patterns change as the viewer moves across horizontally relates perfectly into changing views depending on whether or not the sculpture is viewed coming into the city, or whether they are leaving the city. The sharpness of the mov-ing hyperbolas would relate the driver coming into the fast-paced nature of Mel-bourne city, whereas opening ellipses would give a softer feeling, ideal for some-body travelling away from the commotion of the city.

To visualise this idea, we rendered perspective views of the two different sides of the concept in Rhino, showing the dramatic change that occurs just by being on the other side of the sculpture.