Computational design canopy by Rosanne Chong

Structure of Space

LINEWEIGHTS

Design Development concept

GUIDANCE

INTERACTION WITH ENVIRONMENT

The form of the canopy guides the user through the space. The varying position of the lines and weights creates different spatial qualities. Weights are low at certain areas, creating a low hanging canopy that results in narrow and confined spaces. Weights that are hung higher would result in a more spacious environment. The user experience thus varies as the passageway evolves from being closed and restrictive to being wide and open. The weights are also perceived differently at different points of the canopy. Lowhanging weights that are within an arm’s reach can be fun and interactive, while weights that are much higher up can be admired from down below.

The canopy responds to changes in the environment in many different ways. Firstly, the shadows cast changes depending the sun’s position at different time of the day. Secondly, the presence of wind would cause the weights to sway slightly, making the canopy dynamic. A simple canopy consisting of only line and weights becomes interesting with the many nuances that results from the changing external environment. The user experience is enhanced as the canopy ‘comes to life’ with the swaying weights and dancing shadows.

USING FUNDAMENTAL PRINCIPLES TO FORM A PHYSICALLY SOUND STRUCTURE The canopy’s design embraces a pre-rationalization process. The first priority was for the canopy to be structurally sound, following fundamental principles. The form of the structure would then be directly based off structural principles, allowing for a simple yet reasonable design. For this project specifically, the main driving force behind the design is gravity. The weights cause the strings to sag and the sag points are shifted to create patterns. The organic and seemingly random form of the canopy is derived systematically from a simple code with a few parameters.

Grasshopper Documentation grasshopper synopsis

(clockwise from top-left) overall view of Grasshopper code; first part of code for one curve; second part of code for one curve For this project, we used a C# code for simulating gravity given to us during one of the lab sessions. Using this code, we input curves spanning across the walls. These curves were found by first dividing the top of the walls evenly and connecting lines between them. Weight points were then applied based on the graph mapper onto these new lines, while the ends of the lines were kept as fixed points. The lines thus sagged along a curve that we defined. This entire process was repeated once so we had 2 sets of curves which overlapped in interesting ways. We then varied the stiffness parameter, to get an effect that we liked. Lastly, we managed to extract the information pertaining to the length of the line segments (between each wall and lowest sag point), which would later help us in creating the physical model.

Design Exploration graph mapper

Using the Graph Mapper tool in Grasshopper, we were able to vary the curvature (as viewed from the top) of the lowest sag points as we desired. This allowed us to choose a pattern with a computational basis. We experimented with many of the graph types available, and the results and options are shown below. GAUSSIAN CURVE One of the curves we tried at first was the Gaussian curve. The graph of a Gaussian curve is a symmetrical bell curve. As we intended to overlay this on another curve, this would allow our curves to criss-cross. However, we determined that the visual effect of a Gaussian curve pattern lacked clarity from the user’s point of view. From the front, it is difficult to distinguish the sag points at the rear, for instance.

PERLIN CURVE Another of the curves we tried was the Perlin curve. The Perlin curve is a curve generated based on Perlin noise, a pseudo-random algorithm. The use of the Perlin curve allowed us to create a very wavy curve, which increased the amount of criss-crossing we could produce. However, the design was problematic as it was, again, difficult to read from a user’s perspective, and the sag points were largely in the middle, which made it difficult to use the low points to guide human traffic. BEZIER CURVE The curve we ultimately settled with was the Bezier curve, a parametric curve. The Bezier curve pattern allowed us to run the sag points from the end of one wall to the end of the other, so the span of sag points was evenly spaced and a nice flow could be created. Overlaying this with another Bezier curve could also allow us to compound this effect. The curve was also simple and thus allowed for better clarity from the user’s perspective. Lastly, the Bezier curve was easily customizable, so it suited our design well.

Design Exploration canopy density

Variables changed: number of points on curve one: 15 number of points in curve two: 13 Using this number of lines across the walls resulted in a sparse canopy. This would be nice if we wanted to allow a lot of light through, or really focus on just the weights. However, we felt that it would have little control on light, and thus was unsuitable as a canopy. Variables changed: number of points on curve one: 26 number of points in curve two: 24 This setting was ultimately optimal for our design intentions. We were able to see the curvature and intersections between the two curves clearly enough. There was also enough density of lines to create shade and have control over light conditions between the walls.

Variables changed: number of points on curve one: 46 number of points in curve two: 44 This setting allowed us a lot of control over lighting and also allowed for more definition in viewing the curves. However, due to the size of the weights used, there would be problems created as the weights would overlap, being so close to each other.

Design Exploration stiffness of lines

Variables changed: stiffness: 500.00 This stiffness setting was the closest to the real-world situation - the nylon string we used has a stiffness that is greater than 500.00. However, we wanted a design that allowed the users to experience different spaces in the same pathway, so this stiffness lacked the impact we wanted. Variables changed: stiffness: 50.00 As the stiffness decreases, the sag increases and the level of experience for the users also increases. With the canopy sagging lower and closer to the users, the users will feel more guided along the pathways hinted at by the higher ceilings.

Variables changed: stiffness: 11.11 Decreasing the stiffness of the lines further, we are able to create a greater sag and a better experience for the users as they get to come in close contact with the weights at the lowest sag points, the highlight of our design. As increasing the sag further might result in spaces too low for average users to pass through, we stopped here.

Coded Form a final look in Rhino

Variables changed: number of points on curve one: 26 number of points on curve two: 24 stiffness of curve one: 100.00 stiffness of curve two: 11.11 As we wanted to give the users the freedom to choose the kind of path they want to take when walking through the walls, we decided to use a different stiffness setting on each of the curves so that our canopy can incorporate different levels of sagging and thus enrich the user experience. The set of curves with a lower stiffness setting will have a greater sag, creating a distinct path that helps guide the users along a specific route. At the same time, the curve with a higher stiffness setting does not obstruct the users, instead positioned to add richness to the canopy and add more complexity in relation to the light coming from the top.

(above) a side view of the 2 sets of curves in Rhino

(above) axonometric Rhino view of the walls and canopy in the site

Drawings

axonometric - plan view - section view

(clockwise from top-left) axonometric view; plan view; section view

Renders digital form

view of the space from the wider entrance

Renders digital form

view of the space from the narrow entrance

Model Development documentation of model-making process

One of the first and probably most major decision we had to make during the process of designing our physical model was the choice of string to use for the lines. We first tried normal fishing line (left). However, when stringing the lines, they tended to get kinked easily, and the weights we used were not heavy enough to straighten the kinks. Next, we tested out sewing thread (centre). Sewing thread did not kink, and could be controlled with the weights, but we worried it might be too thick and obvious. Also, there was the problem of unsightly fraying. We then found a roll of thin nylon string (right), which worked much better than expected. While still being prone to kinks, they straightened out with the weights. We also found that the reflective qualities it possessed allowed for some nice effects when under light.

Model Development documentation of model-making process

The weight we used is a fishing weight, which is basically a metal bead with a hole running through the centre. To make the model more presentable and closer to our design intentions, as well as to have a sharper and cleaner angle at the lowest sag point, we devised a method of stringing the lines with the weights. Instead of running strings through the hole, we pegged a loop of metal wire into the hole and ran the string through that wire loop. We then pushed the wire into the weight, such that it was no longer visible. The picture above depicts the weight and wire before the excess wire has been trimmed from the bottom. As shown, the string forms a nice â&#x20AC;&#x2DC;Vâ&#x20AC;&#x2122; shape above the weight.

We used the laser cutter minimally compared to other groups due to the nature of the design. However, the laser cutter was integral to making our model, as it allowed us to precisely plot and cut the holes where the lines were supposed to be attached to the wall. We cut a set of wall additions with holes and a set without (and a set of spares, of course!) out of 3mm MDF board. Pictured above is the laser cutting plan we used. The set with holes is for stringing the lines and goes directly atop the walls. The set without holes is meant to go on top of the first set, acting as a cover. This helps hold the lines down and hides the clutter from the mass of string.

When making the model, we faced quite a number of problems. The strings were very thin and hard to see, and were prone to getting tangled. We thus needed a lot of time and manpower to construct the model despite only having 50 lines. As we were sharing the given wall model with other groups, we also did not have access to it most of the time. This meant that it was very difficult to shift the balls and lines accurately to the positions we wanted them to be at. Transportation and safekeeping of the model is also an issue, as the balls would often shift in position after every move. The balls and string were also hard to glue down, so we had to make do with tape. In retrospect, we could have made our own wall model, given more time.

Model Photography physical form

(above) plan view of the model

(above) view of the canopy from the userâ&#x20AC;&#x2122;s perspective, where there exist a variety of experiences from the different heights and spaces created

Model Photography effects and details

(left) effect of light on the model (above) close-up view of the final construction of weights and string

Digital and Physical a comparison

(left) picture taken with our physical model

(right) rendered image from a similar angle

As is evident in the above images, the physical model is much less organized than its rendered counterpart, largely due to the difficulty in accurately positioning the strings. However, the effect we wanted to achieve is still fairly clear. One can see the alignment of balls in a curve fairly easily, and the balls and lines form shadows on the ground. The materials used are also slightly different, but all in all it was a fair approximation by any standard.