Studio MAKE in Conversation

CONVERSATION #5: Dr Chengzhi Peng and Dr Tsung-Hsien Wang with Chenjun Liu, January 2017

About the project


Chenjun Liu is inspired by Feathers – Pennaceous and PlumulaceousLed by Dr Tsung-Hsien Wang, Inspired by Nature is a five-week long project to explore the underlying formal elements and rules of pattern-forming found in nature.

Beginning with a small scale study, each student investigates a chosen topic of natural evolution through Rhino-Grasshopper based parametric modelling.

The goal is for each student to develop 3D parametric models that simulate the pattern-forming process or behaviour observed. The outcomes are expected to inform further Studio MAKE projects later in the semester.

Chenjun Liu is inspired by Feathers.Two kinds of Barbs show two frame of feather in Pennaceous and Plumulaceous

CP: How did you choose this particular topic of investigation?

CL: Since I was an undergraduate architecture student, I have thought about finding something in nature that shows the combination of its form and function. I found that birds’ feathers have this unique arrangement in which they function according to the different forms, so I decided to work on feathers as my research topic and direction.

CP: What is the key question you have been exploring?

CL: The study of the relationship between the organisation of feathers and their structure and function is the main area of my research. As shown in Figure 1, Pennaceous and Plumulaceous are two basic types of feather. In Pennaceous feathers, the barbs control the growth of barbules which result in two different forms: tight and sparse. The corresponding functions are flight, waterproofing and warmth.


Figure 2. Diagram of Barbs: Controlling the density and extension of feathersTHW: How did you translate the ‘pattern-forming’ system observed in feathers into parametric geometrical modelling?

CL: I started to research the rules of feather arrangement as a combination of geometric objects. I wanted to find the relationship between the arrangement of feathers to inform the shape of my model. However, the research now aims to convert the control points of a single feather shape into the key points in the model so that the shape and form of the model can be controlled by these points (Figure 2).

THW: Can you say a bit more about what is meant by ‘control points’ here? Is it a concept or method mainly from a parametric modelling approach such as the Rhino-Grasshopper?


The grids set different series of control pointsCL: The concept of ‘control points’ comes from the microstructure of the single feathers. I observed that the barbs in the connecting parts between the barbules control the density and morphology of entire single feathers. It seems the locations and densities of barbs play a determining role in feather formation.

In my parametric modelling, I firstly used a grid to get the lines and intersections, and then controlled the number of intersections and arrangements to control the density of lines. As shown in Figure 3, I controlled the two-dimensional grid with different versions and then applied forces through ‘Kangaroo’ - a well-known Grasshopper plug-in. This leads to different 3D forms in three-dimensional modelling, which is the so-called ‘control point control line.’


Figure 4. Barbs and Barbules in a micro-environmentCP: You seem to be adopting a strategy that moves from macro structures of feathers to micro structures. Is this strategy working well in this project?

CL: Yes, I changed the focus of my research from macro structures to micro (Figure 4). I found that in the micro-environment, the feathers are the same among the elements, but the combination of patterns is different, so I developed the idea of multi-layered control points to control the shape in my modelling process.

THW: We see a triangular truss-like structure coming out of your parametric modelling. How is this framework inspired by feathers?


Figure 5. Changing the relationship between barbs and barbules from 2D to 3D through triangulation

CL: I transformed the model from 2D to 3D by introducing the geometric archetype of a triangle. The triangle allows me to change the control points from (a) controlling two lines to (b) three control points controlling multiple lines. In addition, the stability of the triangle is used to ensure that the model remains unchanged when the relative distance between the control points is fixed. I also transformed the model from a triangular prism into a triangular polyhedral structure (Figure 5).

CP: Does the formation of birds’ feathers contain a generative procedure that produces feathers as we see them in nature?

CL: We now know that birds are evolved from reptiles, so the growth of feathers in the early stages of the process is similar to the reptiles’ scaly horny growth of the skin. After the stratum corneum (the outermost layer of the skin) open, barbules grow from the inside of the feather stent, followed by the main growth pattern under the control of barbs.

CP: Have you tried building physical models of the underlying pattern-forming principles of feathers?


Figure 6. Diagram of a physical modelCL: Yes, I tried to use 3D printing technology with different materials in the feather model control point in the production process. I used two kinds of materials, PLA and rubber, with different properties to control the force and direction of the control points. (Figure 6).

CP: How would you summarise the work-flow you have experimented with throughout the project? Is this work-flow new to you? What is the most challenging part of the work-flow?

CL: The whole process is a system consisting of three key steps: (1) select the research subject, (2) extract the key elements of the subject, and (3) transform the elements into a parametric model. While concentrating on my own study, I saw the extractions of different prototypes by other Studio MAKE members who also produced wonderful results. Although I worked with objects or rules extracted from nature in my previous design projects, this project changed my thinking about morphology, function, transformation and derivation.

The design challenge here is how to extract the key elements from the natural life-form studied and how they might be converted to three-dimensional models. I spent a lot of time on this challenge, and finally a relatively complete transformation system was developed.

CP: Given that you had only five weeks from start to finish, you have been successful in showing us how you translate feathers into a parametric model. Can this initial result be developed into an adaptive pattern-forming production system mimicking how nature makes such extraordinary feathers?

CL: The element that I managed to extract from the feathers is not the process of formation, but the point of control of different forms of formation. So we will not be able to produce the same shapes seen in the natural feathers, but change the formation in response to different control points. (Figure 7).

THW: Are there any unique ways to determine the position of these points in conjunction with the control point design, and how do you allow for changes of the control points in response to a changing environment?

CL: I want my parametric design system not only to model the structural form found in nature, but to introduce some interactivity to my model. I want it to be connected to current social media technology such as Twitter. I am working on a Python script for extracting data from Twitter feeds (tweepy), which I learned from another module, Elements of Computational Design 1. The Twitter content used here includes user location, gender, keywords, mood and other data. (Figure 8).

Figure 7. Diagram of comparison Figure 8. The route of data and location framework imposed on the campus site

CP: Introducing ‘social media data’ into your system is a very interesting idea. In my view, it could develop into a dynamic representation of changing environments linked to social data streams. What are you trying to test through this experiment?Figure 9. Hierarchical control related to Tweeter location data

CL: Through tweepy, I can format Twitter data as Excel files, and then import them into Rhino-Grasshopper. This will turn the coordinate data into x, y, for example. I also use other features as inputs to different control points, linking Twitter features to the model at multiple levels. This is to explore a transformation rule mimicking the micro-organisation of bird's feathers such that changes in the control points of my model correspond to a changing environment characterised by users of social media in real-time and places (Figure 9).

CP: Thanks, Chenjun for sharing your Feathers’ story with us. We look forward to hearing from you more about your design development inspired by feathers.


Chenjun Liu studied Architecture (BArch) at the Huaqiao University (华侨大学) in Fujian, China. In his third year at Huaqiao, he had the opportunity to study architectural design at the Department of Architecture at Chung Yuan Christian University (中原大學) in Taiwan as an exchange student. Through this study abroad experience, he decided to undertake the MSc Digital Architecture and Design programme at Sheffield to learn more about Digital Architecture in areas such as data analyses, interactive spaces and digital fabrication.