Hi Daniel,

a parametric modeler is one that's driven by parameters, as
disappointing as it sounds. So, yes, on a basic level ALL modelers can
be considered parameteric.
However, that wouldn't be a useful term since it wouldn't exclude
anything, so when we talk about parametric modelers we usually refer
to indirect parameters.

For example, in Rhino you define a line segment by specifying the
start and end point. This is typically not considered parametric. In
Solidworks you can define a line segment as a tangent relationship to
a circle and a certain length and angle. This would be considered
parametric. One of the major outcomes of this different ideology is
that parametric models tend to be history based. When you define new
geometry using existing geometry, it doesn't take much to change the
starting conditions and have the entire model adjust itself. So, I
think most people will agree that in a non-parametric environment you
directly design the model, whereas in a parametric environment you
design the description of the model. In this light, Grasshopper is
definitely parametric.

However, the term "parametric" has been applied to packages such as
Solidworks and Catia and Pro-E for so long that it is now tightly
associated with that particular style of interface. Perhaps this is
why the term "Generative" has been introduced. To be honest, I don't
exactly know what generative modeling is supposed to be.

--
David Rutten
[email protected]
Robert McNeel & Associates


On Mar 4, 11:37 am, daniel hilldrup <[email protected]>
wrote:
> Hi All,
>
> I don't know if I am in the right place to start this debate, but I am
> looking for answers
> to my questions as I am about to undertake research on the field of
> 'parametric' CAD design and am looking for some terminology
> definitions.
>
> I am a MA product design student looking to adopt some of Grasshoppers
> excellent
> capabilities, and apart from the research would like to know how the
> software is defined.
>
> OK my questions/statement:
>
> What is a parametric design? Is there a definitive definition?
> At a fundamental level isn't all CAD parametric, using parameters that
> state type, insertion point and direction (as with a line). Elsewhere
> I see, dimension based modelers classified as parametric....
>
> Is Grasshopper Parametric? I know that the 'blurb' states that it is a
> Generative Modeler
> using algorithms, so does it make it parametric?
>
> Would really appreciate any sources of information on the definitions
> of generative/parametric modeling and the differences.
>
> Right, back to the hopper to see if I can make something from this
> incredible software!

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