Product(s):	AECOsim Building Designer
	Version(s):	V8i (08.11.09.747)
	Environment:	N/A
	Area:	Architectural Design
	Subarea:	Slabs

Overview

Can I create a Slab by choosing a shape as the Slab's boundary, and then projecting that shape onto the ground geometry below it to determine the Slab's elevation and slope? 

The Place Slab tool always uses the element selected for the Boundary, Flood or Shape methods as both the boundary and location of that slab.  However, there's a fairly simple way to accomplish this result by first using MicroStation's Surface tools as outlined below. 

Steps to Accomplish

1.  Choose Tools > Surfaces > Modify Surfaces > Trim Surfaces by Curves.

2.  Set the Direction to "View", Method to "Project Curve" and Convert to B-spline Surface unchecked.
 
3.  In a Top view, select the shape that represents the ground and then the shape that represents the Slab boundary, and accept.  This should result in the boundary shape projected onto the ground shape.

4.  If the resulting element is a Complex Chain, choose Tools > Groups > Create Complex Shape.

5.  Set the Method to Automatic, select a segment of the new shape, and continue data-pointing until all segments have highlighted. Accept to generate the Complex Shape.

6.  Open the Place Slab tool and set the Place By option to Shape.

7.  Select the new Complex Shape and accept - this should result in a Slab following the shape's boundary but at the slope of the ground geometry.