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TUTORIAL • June 1999

Modeling a World with form•Z

Part of the intention of this tutorial is simply to show how a 3D modeling system can be used to quickly model objects and to explore design possibilities.

by Lucien Swerdloff

3D modeling systems are used in a wide range of disciplines, including architecture, engineering, industrial design, and animation. They are wonderful, as we see in the polished images pervading the media, for developing detailed, sophisticated models of all forms of complex objects. They are, apparently, not so good for sketching design ideas.

One of the major criticisms of 3D modeling systems is their lack of ability to support quick 3D design studies, the equivalent of the stereotypical napkin sketch. Why is it that it is so difficult to use a 3D modeling system to quickly explore design ideas, to make, view, and change simple models of objects? There are a number of reasons, not all of which are the fault of the software. It is true that many 3D modeling systems emerged from the computer-aided drafting tradition, where the intent, the tools, and the interface are geared toward producing accurate, precise, and detailed drawings. It is also true that limitations of current interfaces, both hardware and software, can make working in 3D space tedious. For example, it is difficult to draw a freeform volume in 3D space using a mouse and flat screen. However, an equally important limitation, comes from the attitude and experience of designers using the systems. We are conditioned to think about and use CAD systems as precision tools. We hear about making 3D CAD drawings, for example, rather than designing things.

Part of the intention of this tutorial is simply to show how a 3D modeling system can be used to quickly model objects and to explore design possibilities. Of course these objects can then be made with greater precision and, if necessary, traditional drawings can be produced. The tutorial is also intended as an introduction to some of the 3D modeling capabilities of form•Z. Although form•Z is a comprehensive and sometimes complex system carrying with it as much baggage as any 3D modeling system, it does offer the benefit of a relatively intuitive user interface (a user can, in a few hours, get a good enough sense of it to do design) and an approach that is inherently suited to working in 3D space (rather than in separate orthographic projections of 3D space).

FIGURE 1. The default form•Z interface.

The form•Z Interface

Let’s begin with a brief review of form•Z’s interface. The major areas of the form•Z screen are the graphics window, the tool palette, the menu bar and the floating palettes (Figure 1).

The graphics window is the large window occupying most of the screen, containing a 3D Cartesian coordinate system and a grid (called the reference plane). It is where objects are created, manipulated, and displayed. The window tools palette is located along the bottom edge of the graphics window. This palette contains tools that control the graphic environment of the window, such as selecting different grids, zooming, and grid snap.

The tool palette, located on the left side of the screen, is the primary means of selecting modeling tools. There are two types of tools: operators and modifiers. Operators, displayed in black and white, generate or manipulate objects. Modifiers (second row; fourth row, left column; and eleventh row, left column), displayed in teal and magenta, set modes affecting the actions of operators. One modifier in each row of modifiers is always active and determines the behavior of any tool that is selected. For example, notice that the 3D Extrusion modifier in the second row is selected by default. Click on the Rectangle tool in the third row and pick two points in the graphics window. A box is generated: the result of extruding the rectangle up. Now select the 3D Convergence modifier in the second row. The Rectangle tool is still selected so pick two points in the graphics window. A pyramid is generated: the result of converging (extruding to a point) a rectangle. So the same tool is used to generate different forms from the same base shape depending on the active modifier.

The menu bar across the top of the screen contains standard pull-down menus (e.g., File and Edit) as well as items specific to form•Z (e.g., Heights, View, and Options).

The floating palettes, located in various places on the screen, provide information (e.g., Coordinates and Prompts) and the means to control various functions (e.g., Tool Options, Layers, and Lights).

Setting up the Work Environment

Although form•Z has a fairly intuitive user interface, a few simple things can be done to customize the working environment for easier use.

Individual rows of the tool palette can be torn off and made into free-floating palettes. Tool palettes are the primary means of selecting modeling operators. There are 14 rows in the tool palette along the left edge of the screen organized into two columns, most containing a number of tools. Although they are reasonably well organized, it is often difficult for the beginning user to remember the location of all the tools. Tearing off the rows that are commonly used lets the user see all the tools at once (although it can clutter the screen). We will tear off three rows of the tool palette containing commonly used modeling operators: Generation (second row, left column), Polygons & Circles/Ellipses (third row, left column), and Points, Lines, Splines & Arcs (third row, right column). To tear off a row, place the cursor on the row, press and hold the mouse button so that the row is expanded, drag past the end of the row and release the mouse. Once torn off the palettes can be arranged on the screen or closed like any floating window. Window tools palettes can also be torn off. Tear off the Zoom & Pan palette (second from the right side of the window tools palette along the bottom of the graphics window).

Turn off the sun symbol so that it doesn’t interfere with the display of objects. The sun symbol, the small circle with arrow, indicates the direction of light for shading. Turning it off simply removes the display of the symbol from the screen without affecting its parameters: It will still shine light. Click twice on the diamond icon (¨ ) in the row named Light 1 in the Lights palette.

Simplify the display by closing and rearranging palettes. Click on the close button for the Lights, Objects, Layers, Views, and Animation palettes. Since we will not be using these palettes for this tutorial, closing them provides more screen space. They can be opened again by selecting them in the Palettes menu. Move the Surface Styles and Coordinates palettes to the empty area on the right of the screen and arrange the torn off tool palettes on the screen by moving them to the edges of the graphics window. Figure 2 shows the customized interface.

FIGURE 2. The customized interface. Modeling tool palettes are torn off, unused floating palettes are closed and palettes are rearranged on the screen.

Turn off the display of ghosted objects. Select Hide Ghosted from the Edit menu in the menu bar. Ghosted (or inactive) objects are created when operators destroy existing objects: for example, extruding a circle to form a cylinder ghosts the circle; joining two cylinders together to form a complex object ghosts the original cylinders. Ghosted objects are displayed in gray in wire frame views. Hiding ghosted objects clarifies the display, allowing the designer to focus on the active objects. Ghosted objects are sometimes used (by unghosting them) to restore previous versions of a design.

Finally, we will set the method of indicating the height of extruded objects to interactive mode. The default method of creating a 3D extruded object is to use a preset height. Changing to interactive mode allows the height to be graphically indicated by moving the mouse, allowing for a much more fluid method of modeling. Before we make the change, let’s make an object using a preset height to compare the two methods. Select the 3D Extrusion modifier (third icon in Generation palette) and the Polygon tool (third icon in Polygons & Circles/Ellipses palette). Pick two points in the graphics window to indicate the center and radius of base shape. A 3D solid is generated. The solid is 10 feet high, the default height setting. Select Graphic/Keyed from the Heights menu in the menu bar. Pick two points in the graphics windows then slide the mouse to indicate height and click. Notice the height is tracked in the Prompts palette as the mouse is moved. If a more exact height is required, it can be typed into the Prompts palette followed by Return or Enter. The interactive heights mode is particularly useful for design explorations where it is important to be able to see and compare objects as they are being made. Use the Delete tool (last row, left) to remove all objects.

And now on to the models. The examples used in this tutorial are designed to show general methods of making 3D models. Therefore the emphasis is on quickly modeling and working with objects in 3D space. Once the techniques are mastered, you can easily reconstruct the models with more precise dimensions if you wish.

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