Last month, in Mass Modeling the Autodesk Architectural Desktop Way, we looked at the Mass Elements and Mass Groups functionality in Autodesk® Architectural Desktop Release 3. These tools help you quickly build 3D models. This month we'll explore the undocumented MASSELEMENT > CONVERT command and how it can help you even more. (This command is not supported by Autodesk, so use it at your own discretion.)

ACIS Solid Models
Although the Mass Elements capabilities in Autodesk Architectural Desktop software are effective, they do have their limits. You cannot edit Mass Elements at the face level, and you cannot apply sweeps to them. But you can get around these limitations by creating and editing your solid models with the software's ACIS solid-modeling kernel, then using the MASSELEMENT > CONVERT command to convert ACIS solid models into Mass Elements. It works great except that doors and windows don't insert correctly in curved boundaries; this should be corrected in future updates.

The ACIS kernel consists of routines for creating and editing solid models that mimic the real-world behaviors of solid objects. These routines include primitives such as box, sphere, and so on, which are similar to the Mass Element primitives. The difference is that with the ACIS routines you can edit down to the face level of an object.

Let's work through the following exercise to see how you can create Mass Elements from ACIS models and then convert the Mass Elements into walls.

Creating a Solid Model
1. Start a new drawing using the Aec [imperial] massing template.

2. Activate the Solids, Solids Editing, and View toolbars by right-clicking any AutoCAD®-specific icon, and selecting these toolbars from the resulting contextual menu.

3. Select the Mass-Group Layout tab and set the left viewport to Top View.

4. Using the Rectangle command, place three rectangles sized as shown in Figure 1.

5. Select the Extrude icon from the Solids toolbar, and extrude the following measurements as shown in Figure 2.

You have now created a solid object.

• Rectangle A = 30' x 50'
• Rectangle B = 15' x 35
• Rectangle C = 20' x 20'

Figure 1: Use three rectangles (polylines) to create your design.

Figure 2: Extrude your rectangles.

6. Again using the Rectangle command, add a new rectangle to the object you have just created (see Figures 3 and 4).

Figure 3: Add a rectangle (polyline).

Figure 4: Rotate the rectangle in place from the Top View.

7. Select the Slice command from the Solids Editing toolbar, and select the solid made from rectangle A, then select O (Object) from the command line.

8. Select rectangle D as the O (Object), and type B at the command line to keep both sides.

You have now created a new solid object (see Figure 5).

Figure 5: After the Slice command, you have a new object.

9. Select Extrude Faces from the Solids Editing toolbar, and extrude the new object faces 10' higher, and 25' outward. Then move the new figure 10' away from Object A as shown in Figures 6 and 7.

Figure 6: Extrude the Faces of the new Object.

Figure 7: Move the new Object.

You have now completed your massing model using the ACIS solid-modeling kernel.

10. Type masselement at the command line and press Enter.

11.Type C, for convert, on the command line and press Enter.

12. Select each of the objects and name them A, B, C, and D respectively, erasing their layout geometry when prompted by the command line.

You have now created Mass Elements, which can be modified as shown in last month's column.

Mass Groups
13. Select Concept> Mass Groups> Add Mass Group from the main toolbar.

14. Add the Mass Group object in the viewport (the rotation angle doesn't matter) and press Enter.

15. Select the Mass Group object and right-click to bring up the contextual menu.

16. Select Attach Elements, and select the Mass Elements you created earlier.

17. Select the Layers icon, and freeze the A-Mass layer to leave the Mass Group.

18. Select Concept> Slice Floorplates> Generate Slice from the main toolbar.

19. Enter 5 (for 5 slices) at the command line and press Enter.

20. Select two corners for the Slice Object indicator, and accept 0.00 as the rotation angle. Accept 0" for the starting height, and make the distance between slices 10'. (See Figure 8.)

Figure 8: Apply Sliceplates to your design.

21. Select all the Slice Object indicators and then right-click.

22. Select Attach Objects from the contextual menu that appears and select all the Mass objects.

You have now sliced your Mass Object into floorplates.

23. Select the Layers icon, and freeze the A-Mass Grps layer to leave just the floor slices.

24. Select Concept> Space Boundaries> Convert to Boundaries from the main toolbar.

25. Type SL for Slice at the command line, press Enter, select all the slices, and press Enter again to bring up the Space Boundary Properties dialog box.

26. At the Space Boundary Properties dialog box, choose the Design tab, and change the wall base height to 10'. Click the OK button and then press Enter to close the command.

You have now gone from the conceptual stage of your design to the Space Boundary stage where you can generate walls and add doors and windows. (See Figure 9.)

Figure 9: Your model is ready for walls, doors, and windows.

Conclusion
In this article and last month's, we looked at only a few of the editing capabilities available to you with the Mass Elements tools in Autodesk Architectural Desktop software. You're sure to learn more as you work with the MASSELEMENT > CONVERT command. With a little practice, you should be able to develop your ideas into complex 3D models very quickly.