2nd generation of 3D printed Shells for Visualise

July 25, 2012 by  

I have just come back from the Digital Manufacturing Centre 3D printing lab at UCL where we just had our second round of shells made for us.

This time around you can see shells which are beginning to have some life (or data to be exact) put in to them. They are ‘grown’ by using the health data we have previously collected from the body sensors and data logger which we are beginning to use to evolve different types, shapes and sizes of shell.

We captured the initial data over a week back in May which consisted of blood pressure, step counts, length of sleep, body temperature, exposure to air pollution and alcohol intake. These were gathered to provide a range of values we could use  to make the shells change the way they are evolved over time.

These different dimensions of data are used in our growth model as parameters that influence where and how much the shell grows and in which particular way. Each set of data values contribute to determining how much it grows, how smooth or jagged the surfaces are and whether or not there are other outgrowths. All together this results in a very personalised and specific shape that is unique to each data set.

We are planning to fabricate two further sets of shells, one with more extensive data sets informing the shell growth pattern, and the second experimenting with different data sources. More posts to come!

Our growth model as mentioned before is using variants of ‘parametric design’ via L-Systems and Growth Grammars. Here is a very quick explanation of what these do in principle:

Parametric Design
In a parametric design different numerical values – called parameters – are put into a set of related mathematical formulas or rules. These are able to generate variations of shapes or objects based on different input values. It is for example possible to create a parametric definition of a basic chair that  when combining the height and leg length of a person – can generate a chair with proportions that make it comfortable for that person to sit on. So a parametric design in this case captures the idea of a chair that can be made to fit different bodies – i.e. how many legs the chair has, the way the legs are connected to the seat area, the seat sitting area and the height position of the backrest.

L-Systems
These were invented by a man called Aristid Lindenmayer and are type of formal language that uses sequences of letters that define how something grows over several time periods. They can for example express how a tree expands from its trunk into branches and then into leaves or how a flower’s petals are arranged.

Growth Grammars
These are more complicated variations on L-Systems that have a richer set of features that can be used to describe growth models such as plant models. Growth Grammars are used in not just modelling the structure of plants i.e. how it is put together and its parts but also how it functions and its parts interact with each other.

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