Introduction to Parametric Modelling with Grasshopper

Traditional 3D modelling programs allow us to create 3D objects with tools that somewhat simulate how one might sculpt them in the real world to a high degree of accuracy. We start by creating simple shapes, and by using variety of commands are able to carve and mould these shapes into more complex objects. Designers work from briefs that state specific requirements and conditions to which designs must adhere and respond. The design process can be a lengthy exercise of product reworking in order to satisfy a variety of changing conditions (budget, legal, clients, materials, fabrication limitations, etc). As a result of these changes it is sometimes necessary to restart a design from scratch, delete and add parts to the design, or go back to an earlier version and continue from there. This process of reworking can be extremely time consuming.

But what if instead of going through this manual process of 3D drawing, we could automate it and give our designs the ability to respond to these changing factors? Parametric modelling allows us to automate the 3D modelling process and provides the designer with the power to simply generate infinite design variations. This is because when we design with parametric modelling software such as Grasshopper we give the 3D program a set of instructions (called a script) where each design step performed on an object is dependant on other steps in the process. This means that we can revisit the script we have produced, change part of it, and all the steps that are dependent on the part we changed will adjust themselves in response to the change.

For example, we may use a traditional method of modelling to draw three circles next to one another where the first one is double the size of the second one, and the third one is double the size of the second one. If the size ratio conditions change and we have to make the first one three times the size of the second one, and the second one three times the size of the third one, we would have to redraw at least the second and third circles to comply. With parametric modelling tools we are able to change one number value that represents the dependency of the circles size in relation to the previous circle in the group. By changing this one value the drawing will automatically adjust and the circles will redraw themselves to fit the new conditions. This simple example applies to the most complex objects and conditions we create in the parametric modelling environment.

In addition to being able to create highly adaptable designs, another advantage of parametric modelling is that it enables us to create very complex designs with mathematical properties that would be otherwise near impossible to devise. You will see examples of this type of complex geometry in architecture in Hank’s lectures.

Grasshopper is a plugin for the Rhinoceros 3D modelling environment which uses the built-in Rhino commands for parametric design in a visual programming workspace. It is generally used in combination with the regular Rhino environment to achieve the desired results. There are several programs like Grasshopper that allow users to take advantage of the power of parametric modelling in various modelling software environments, such as AutoDesk (Revit, Vasari, Dynamo) and Microstation (Generative Components).

Before our first tutorial class on Wednesday 5/3:

1. Read the first two pdf’s linked to the tutorial page of this website: http://parametri.dk/tutorials/. This will give you a basic understanding of the Grasshopper environment.
2. Sign up to the Grasshopper 3D forum: http://www.grasshopper3d.com/main/authorization/signUp?
3. Check out Digital Toolbox http://digitaltoolbox.info. It is another great tutorial resource.
4. Have a look at the official Grasshopper 3D Primer: http://www.liftarchitects.com/blog/2009/3/25/grasshopper-primer-english-edition

We will post more links to tutorial sites on this blog soon, and you can also find tutorials or forum posts that answer many questions you have about Grasshopper. Google is your friend :)

Remember: If you don’t understand what you’ve just read in the links above, don’t worry! That’s what your tutors are here for. The concepts may be a little different to what you’re used to and difficult to understand in the beginning, but once it clicks it will become a lot of fun.