RhinoInsideRevitEssentialGuide

Webpage link: https://www.rhino3d.com/inside/revit/1.0/guides/revit-revit
This article is the note after I read the essential guide from RIR.

The Element DNA

Keep in mind that not every element has geometry. Some of these elements might only carry information.

• Category
  defines the highest orgasnization level and carries a template for input and output properties of the element. The category list is built into Revit and cannot change.
• Family
  defines the second organized level. Family is like a function f(x), that takes inputs from type and instance parameters, produces metadata, and geometry.
  The family logic is either built into Revit as System Families e.g. Floors, Walls, and Roofs, or can be defined using Custom Famuilies e.g. Doors and Windows.
• Type
  defines the third organization level. Type also carries value of type parameters. These values are fed in to the Family function to generate the element and calculated type parametes.
• Instance
  carries transform information that places the element in the 2D or 3D space. It also carries values of instance paramters. These values are fed in to the Family function to generate the element and calculated instance parameters.

So practically, we feed type and instance information into the family function, to generate the element metadata(including calculated properties) and geometry.

The generated elements are stored in a Revit Document. They are also organized by a series of Containers.

Subcategories can be think as a property of geometry.
When a Family function generates geometry, it can group them into subcategories of the main category.

Elements & Instances

• Elements are the basic building block in Revit data model.
• Elements have Parameters that hold data associated with Element.
  • Bulit-in parameters
  • custom parameters defined by user.
• An Element could
  • has geometry (e.g. Walls(3D), Detail Components(2D))
  • has no geometry (e.g. Project information)