Early in my career I was often pulled into projects for a short time to meet a deadline. One such instance was when I was asked to develop a paving pattern study for the San Mateo County headquarters building. Our design principal's exact instructions were incredibly labor intensive, so I saw this as a perfect opportunity to apply my interest in computational design to optimize our office's rapid prototyping workflow.
Team
David Gastaneta, Kevin Conger
Client
San Mateo County / Studio Gang
Role
Project Designer / Parametric Designer
Skills / Tools
Parametric Design, Rhino, Grasshopper, Illustrator
THE DESIGN PROBLEM
The proposed design for the San Mateo County building - designed by Studio Gang - is elevated by a series of architectural stilts which frees up the ground plane for a large public plaza. Since our client wanted the plaza to remain unobstructed for public gatherings, CMG was challenged to come up with a paving pattern that would create visual interest and break up the monumental space.
Early rendering of the "Common Ground" plaza (Credit: Studio Gang & CMG)
The plaza's footprint took the form of an irregularly shaped blob, measuring 12,600 SF in area. Although we were excited by the sheer amount of space to work with, we knew it would prove challenging to keep the plaza visually interesting while leaving it open enough to allow for flexibility of use. Before we even began our design process, we framed our key design goals as follows:
1. Create a visually interesting pattern to add texture to and break up a monumental space
2. Create a pattern that reflects San Mateo County's diverse environments
3. Propose a custom design that can be implemented in a cost-effective manner 
THE CONCEPT
After a brainstorming session with our client, the project's design principal decided that our pattern's form would somehow reflect the natural history and ecology of San Mateo county. The diversity of biomes in the county is staggering, ranging from redwood forests to ocean beaches and oak savannas. Our team used images of these ecosystems to draw inspiration for our pattern, which we compiled into a precedent images board for our project.
Character imagery from various sources
The project's design principal then sketched out a few options for me to model, to see how they would look in the space. The idea was to create an abstraction of the natural patterns by using two contrasting colors of pavers.
Abstract sketches by Kevin Conger.
While I was modeling these concepts for the principal, I had an idea. I remembered coming across an "image sampler" someone on the internet made in Grasshopper, a parametric design plug-in for Rhino 3D. The image sampler would basically take an image and break it up into 2d geometry, creating an abstract pattern based on the image. Since we were on a strict timeline, I thought this might be an efficient way to test a ton of different designs in a short period of time.
Example of a Grasshopper image sampler, Credit: Generative Landscapes
DEVELOPING THE SCRIPT
To see if my idea would even work, I found the image sampler script off the internet and plugged in some of the character images we had gathered. Although the results were promising, I thought it needed to be more developed and visually interesting before I took it to the table at our weekly design meeting.
An example of the patterns produced by the default script using our favorite character images (Top). Enlargements (Bottom).
Since my initial idea had worked pretty well, I felt comfortable playing around with the default script to get a richer design. The first change I made to the script was to simply change the generated shape from rectangular to circular units. Then, I added a custom function to the script which cropped the generated pattern to the footprint of our plaza.
The script I created allowed me to produce multiple iterations of patterns in a very short period of time. I plugged in all of the images that my team had identified as their favorites, and exported some birds-eye and ground-level views to show the pattern in context. At the end of the week I took my ideas to the team and they loved the patterns that my process had generated. 
(Left) Mud Flats, (Center) Wood Burls, (Right) Wetland Sand.
Although the team was happy with the general direction my design was heading in, there was one recurring problem that I kept running into. Some of the patterns were not orienting to the plaza footprint the way I wanted. In order to resolve this issue, I added a custom script that would rotate the pattern by a specified number of degrees. 
Script with rotation function added (Top). An identical pattern rotated 0, 45, and 90 degrees (Bottom).
Once I had tested our patterns at a variety of rotations, I brought my iterations back to our team. At the end of our design meeting, the team had decided that we would proceed with the pattern that we had named "Underwater Ripples".
"Underwater Ripple", the pattern out team chose to advance further.
ITERATING FOR CONSTRUCTABILITY
Now that we had chosen a favorite pattern, it was time to revisit my design to see if there were any other issues. The first thing I noticed was that there were too many unique diameters of circles, which would complicate construction due to the sheer amount of variation. To solve this issue I modified the script to take the values being spit out of the image sampler and bound them to just 3 unique values ranging from 1"-8". Then, the three values that were generated were redefined to equal a set diameter, in this case 4", 6", and 8". Now instead of having an infinite number of diameters, we were working with just three standard dimensions.
Screenshot of the script, modified to produce a pattern with constrained diameters.
An example of the exact same pattern, before (left) and after circle diameters were constrained (right).
Although the resulting design worked out in plan, I rendered it out to see what it would look like at eye level. The visual study revealed that this design was barely perceptible from eye level, since there was not enough visual diversity. In order to address this problem I played around with the resolution of the pattern, trying three different U and V values while keeping the same dimensions of the circles. In essence, this preserved the dimensions of the circles while increasing or decreasing the spacing between them. Of the three options I tried, the team agreed on a medium resolution pattern, with circles being spaced 15" on center. 
The original pattern (left), the same pattern at high resolution (center), and the final mid-resolution pattern which our team ultimately chose (right). 
Once we landed on a design that we were happy with on the screen, it was time to test it out in the physical world. In order to visualize what the design would look like if built, I printed a section of our final pattern out at full scale and placed it in the lobby of our office. I also printed out some options that we had explored earlier, allowing our team and others in the studio to comment on which option they preferred.
Kevin Conger, founder of CMG, evaluating a full-scale mockup of my design. 
Rendering of the San Mateo County Building, featuring my paving pattern in the plaza. (Credit: Studio Gang and CMG)
IDEAS FOR IMPLEMENTATION
After presenting our design to the building architects and client, we received the green light to incorporate our concept into detailed construction drawings. Although we had a clear design in mind complete with precise dimensions, we did not yet have a strategy to build the pattern we had on screen. Our team began to brainstorm ideas for the best way to construct this design, consulting with employees in our office that specialize in construction. The brainstorming session resulted in a list of viable options that highlighted the pros and cons of each method, as seen below:

Decision matrix highlighting the pros and cons of each construction method that we evaluated.
After evaluating all our available options, we decided to proceed with the sandblast method. Although this method couldn't provide as strong a visual contrast as some of the other methods, it stood out due to its low cost and ease of implementation. The process would work as follows: 
1) CMG would develop a custom rubber template that reflects our desired pattern.
2) Contractors would pour concrete, filling up the footprint of the plaza.
3) The contractor would lay the custom template over the finished concrete and sandblast over the template.
4) The template is removed, revealing dots of contrasting texture where the concrete was sandblasted. 
Example of a pattern created using the sandblast method (Source: Graco.com).
Now that we had our construction process worked out, we began to detail a small section of our design to see what the pattern templates would look like in practice. We chose to use a thin 3'-8" x 7'-0" rubber sheet, which is easily and cheaply available due to its manageable size. We would then send the plates to have the pattern cut into them either by laser or water jet. With this pattern mock-up complete, we had successfully transformed our concept into a design that could feasibly be implemented on site. 
Construction diagram outlining the layout of rubber templates that would be sandblasted to reveal our pattern.
RESULTS AND LEGACY
As a result of my efforts on the team, the project had a novel design concept that was fleshed out enough to convince the client that it could be built in a cost-effective manner. My well documented grasshopper script also allowed future designers working on the project to further iterate on the pattern even after I was off the project. If this project comes to fruition as currently planned, it will be the largest - if not only - known project of its kind to use this technique.
On a personal level, my relatively short two-week long involvement on this project changed the course of the plaza's design entirely. I was able to have a lasting impact on this project by proposing a concept that was taken all the way through to construction documentation. Ultimately the project was left with a unique pattern that reflected local ecology while breaking up a monumental space, meeting all the goals that we set to achieve at the beginning of our design process. 
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