# 3D Modeling Special Interest Group – December 2018

In this session, we discussed how to go about modeling various objects in 3D, making the simplest shapes with extrusions and proceeding to increasingly more complicated shapes made from multiple extrusions, sweeps, Extrude Along Path, NURBS curves, and subdivision modeling.

Topics Covered:

• 00:07    When you set about modeling something in 3D, how do you decide whether you need a curvy shape or a rectilinear shape—or just where to start? We talked about things to consider as you begin to model an object, such as a Tizio table lamp. I like to start by breaking the object up into simple parts and then seeing which of those can be created using extrusions—as those are by far the easiest to create. For example, we saw that the base of the lamp could be made from an extruded circle. If an object has tiny parts, I tend to ignore those. There are two ways to control the graphic qualities of an extrusion: The Attributes palette can be used to give it a solid color and the Object Info palette can be used to give it a texture. Often, I like to draw in an orthogonal view so that I can be sure to get all of the heights right.
• 12:44    Extrusions are always perpendicular to the plane of the object, and they always start at zero on the working plane. If I can, I like to create my model at (0, 0) so that it is easier to place the various parts of the object. We covered how to model a curvy shape that’s tapered. The Multiple Extrude command can be used to make a tapered rectilinear shape. Using an object’s profile and the Sweep command can create a tapered shape that’s curvy—an object that looks like it could be made on a lathe. Double clicking on the object reveals its original shape. If parts can’t be created using extrusions, multiple extrusions or sweeps, I look at using Extrude Along Path or NURBS curves.
• 26:46    Next, we demonstrated creating parts by using the Extrude Along Path command, including how to edit the path or profile of the object. We made a handrail, interrupting it with columns by using the Subtract Solids command and adding horizontal bars by editing the Extrude Along Path profile. We showed how to model a baseboard for a wall with different slopes at the bottom. We wanted to use the Extrude Along Path command. First, we created the path by using the Extract tool in Extract Curves Mode to get a NURBS curve that could follow the bottom edge of the wall. Then, we created the profile of our baseboard. Vectorworks centers the profile along the intersection of the green and red paths. Usually, it is necessary to adjust the profile.
• 54:33    The curviest objects require using subdivision modeling. Sometimes, the most challenging part is selecting the right shape to start with. Often, once you have the shape, you just have to fiddle with it to get the end shape that you want.

3D Modeling December 2018

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