Graphics Programs Reference
In-Depth Information
Making Holes in a Surface with the Project Geometry Tool
Eventually, you'll need to place an opening in a surface, so AutoCAD offers the Project
Geometry tool. This tool allows you to project a closed 2D object's shape onto a 3D surface. For
example, if you want to place a circular hole in the surface you edited in the previous exercise,
you would draw a circle parallel to that surface and then use the Surface Projection UCS tool.
Try the following exercise to see how the Project Geometry tool works:
1. From the Layers palette, turn on the Circle layer. A circle appears in the drawing.
2. Type UCS ↵ and then type OB ↵. This lets you align the UCS to an object.
3. Click the circle to align the UCS to the circle.
4. Type SURFACEAUTOTRIM 1 ↵ to turn Autotrim on.
5. Type PROJECTGEOMETRY PRO U ↵.
6. Click the circle and press ↵.
7. Click the surface. The circle is projected onto the surface and the area inside the projected
circle is trimmed (Figure 23.55).
FIGURE 23.55
The circle pro-
jected onto the
surface
In this exercise, you aligned the UCS to the circle. The Project Geometry tool you used in step 5
projected the circle in the Z axis of this new UCS that is aligned with the circle.
The other two Project Geometry options use different criteria to project geometry. The View
option will project geometry along the line of sight. If you had used this tool in the previous exer-
cise, the projected circle and opening would appear directly behind the circle from your current
view. The Points (or Vector) option projects geometry along a vector that you indicate with two
points. You can use the 3D object snaps to select points on the geometry and the surface.
Visualizing Curvature: Understanding the
Surface Analysis Tools
In addition to the surface editing tools, AutoCAD offers several surface analysis options. These
options offer some visual aids to help you see the curvature of your surface's models more
clearly. They can be found under the Analysis tool group on the Tool Sets palette and are called
Zebra Analysis, Draft Analysis, and Curvature Analysis.
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