Stupid question, what is parametric

OK, so I have been printing going on 4 years now and I see a lot of objects say "parametric" and I just wondered what that means exactly? I looked it up online but the definitions I read don't seem to apply to 3D objects.

Thanks

Edited 1 time(s). Last edit at 01/25/2015 10:18PM by tmorris9.

What that usually means is that the object is defined with formula - so that you can change various characteristics of the object by just changing a variable's value. For instance if you just want to make a part wider, you can increase its width variable and all the other characteristics adjust to the new width value.

If an object is not parametric, adjusting the width might make two parts collide for example. I would be willing to bet that many objects that are described as parametric are not truly parametric. I think it can be an over-used adjective.

Hello,

Could you edit your post and give it a meaningful title? Like "What is a parametric model".

The most basic definition of parametric in the context of CAD is that an object can be controlled through parameters. See [en.wikipedia.org]

The term was coined first by Parametric Technology Corporation (PTC) in the late eighties when they introduced Pro Engineer (now Creo). The idea is that each time you make an operation on a part, it is saved as a specific step known as "feature" and listed in a history tree. Most features are first defined by a sketch which is usually a 2D profile. At any time you can go back to any of those feature to change their parameters (length, width, radius and so on).

This animated GIF taken from Wikipedia shows pretty well what I'm clumsily trying to convey:



Most of the designs found on Thingiverse labeled "parametric" were created in OpenSCAD, which defines object by parameters, but solely through scripting (lines of code) rather than by using GUI tools. In professional CAD, scripting is available to automate tasks, but it's not the only way to produce geometry, and AFAIK most CAD operators use GUI tools exclusively.

The most well known commercial parametric modeling software are CATIA, NX, SolidWorks, Autodesk Inventor but there are many more.

In the open source area, there are only three desktop parametric modeling software that I know of:

• OpenSCAD (script-based, and known as "The Programmers Solid 3D CAD Modeller")
• FreeCAD, in continuing development with a well-featured GUI, multi-platform (Windows, Mac, Linux)
• NaroCAD (Windows only, not as far advanced as FreeCAD because the project was started years later)
• I'm not sure if BRL-CAD can be considered as parametric, I don't have any experience with it.

In the world of architecture there is also parametric design. Basically they put a formula into a 3D-program to generate shapes with distinct repetitive features such as 'Voronoi's and it attributes to buildings not being user-friendly anymore since 99% of the design is done in the computer and not with the bare hands.

This makes up for some pretty flashy architecture but it's usually just landmarkish and that's it. When you think of parametric design in architecture you think of 'Zaha Hadid' (google her name), her design office makes the weirdest stuff, it's not even funny anymore.

In my opinion parametric design should be a tool to help design the technical aspects of a building. It becomes problematic when you design things for 'the human dimension' with parametric formulae.

Oh, and good morning
(I'll edit this post later on to expand on the subject and give more examples)

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http://www.marinusdebeer.nl/

OK I think I get the gist of it.

Thanks