Wednesday, May 9, 2012

Slab Depression - Part 3

Revit facilitates an iterative process in which the output is constantly being improved. For many Revit is the antithesis to CAD, where, due to the complexity of the system, the goal of quality is often perceived to be an effect of consistency, which is pursued through standardization.

With Revit quality is seen to be an effect of innovation, within a modular system that supports and facilitates innovation. Once every year a new version brings new tools and functionality, to be implemented as needed, but in practice the improvements are incremental and continuous.

Soon after I deployed the Slab Depression families I received a request to slope the depressed surface to enable tagging with spot slopes. It was a fairly easy task to enhance the original void extrusion with a blend tapering from the outer boundary to a three inch square bottom surface representing the drain location. 

The depth of the depression, however, had to be set manually in order to achieve the desired slope, more or less by trial and error. 
The required depth for any slope is determined by the longest distance from the perimeter to the drain. 
An Internet search on "Revit conditional formula" led to this discovery on Autodesk WikiHelp:

if(A > D, if(A > C, if(A > B, A, B), if(B > C, B, C)), if(B > D, if(B > C, B, C), if(A > D, if(A > C, if(A > B, A, B), if(B > C, B, C)), if(B > D, if(B > C, B, C), if(C > D, C, D)))))

This is a conditional formula which by comparison returns the largest of four different values  originally posted  by 'ekkonap', a Revit user in the Netherlands, on
The formula variables were equated to the four distances, and the depth calculated as a percentage (0.25/12). This slope factor could also assigned to a parameter.
The faces of the depression may be painted with floor materials, or for simplicity a level floor may be placed into the recess. As a serendipitous effect of this modeling strategy, the slope lines are now edges which can be transformed to hidden lines with the linework tool. 

Go to the Files and Families tab above to download "GEN_Slab Depression w

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