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    by Dennis Collin

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    It is easy to model hard edge geometry in Revit like columns, walls, slabs, doors and wooden furniture, but what about soft furnishings like cushions, chairs and curtains? These elements need to look softer and are difficult to realise without excessive modelling of cuts and voids.

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    Fig 1. Revit 2024 has many file import options when making component families!

    Newer versions of Revit will let users import curved meshes in from other products like Rhino, Sketchup and 3ds Max, but there may be a need to modify the incoming geometry and apply parameters, which cannot be done unless using 3rd party plug-ins or the BIM exchange workflow with Autodesk Inventor.

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    Fig 2. Revit’s legacy modelling tools do not make it easy for users to quickly make organic/soft forms.

    Revit’s modelling tools, at first glance, do seem a little limited in the main family template environment as tools like extrude, blend and sweep etc. do not provide options to fillet edges unless several void cutting objects are applied making the creation of an object like a cushion or curtain somewhat tedious. Issues can also occur with the mapping of textures when using sweep tools, or when mirroring geometry.

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    Fig 3. Regular modelling tools are fine for modelling handles and curtain fixings.

    However, by using an adaptive component template users can leverage its create form geometry tool and define a series of cross-sectional and guide curves and model more organic forms using ‘Loft’-like modelling tools. The term Lofting comes from the ship building concept where a keel is laid (path), cross beams set out (profiles) and the hull planks or plates fixed to the structural frame (or guide curves / form geometry).

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    Fig. 3a Categorising a component.

    The generic model adaptive component can be categorised in the same way as other Revit Families via the Family categories and parameters function.

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    Fig 4. Choose Generic Model Adaptive for the ‘organic form’ function.

    From the adaptive component template, a series of reference curves and points can be created forming the skeleton of the cushion or other required form.

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    Fig 5. Creating a form from profile and guide curve(s). A Cushion’s ‘skeleton’!

    These elements can be selected and an irregular organic form can be created. A fabric material can be applied to enhance visual views and if required, the skeletal framework can have parameters applied, or if desired the points can be set to ‘adaptive’ so that points and their related geometry can be stretched to an appropriate size. Adaptive components are workplace based and will snap to surfaces, snap references or user defined work planes.

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    Fig 6. The completed cushion component with a fabric material applied.

    Like other families’, properties can be scheduled and tagged if parameters are set as ‘Shared’. It is also possible to nest the family so that the cushions will be present when placing sofas, chairs or bed components.

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    Fig 7. A similar approach could be used to model features such as curtains.