Graphics Programs Reference
In-Depth Information
The final product of a grading design is a surface—the same type of object you
used to model the existing terrain in Chapter 4, “Modeling the Existing Terrain
Using Surfaces.” As you may recall, to create a surface representing existing ground
(EG) elevations, you use breaklines drawn along linear terrain features such as
curb lines, ditch lines, and so on. You can use the Civil 3D tools to make these
breaklines from data collected in the field by surveyors. To create a design surface,
you draw breaklines along curbs and ditch lines that are
going
to be built in the
field. The process is fundamentally the same as creating an EG surface except that,
in this case, the linear features are part of your design. For example, in Figure 17.1,
you see the grading design for a pond represented by the red and blue contours.
Civil 3D tools were used to draw the edges of this pond according to the required
design specifications such as size, shape, depth, and so on. The objects representing
the edges were then used to build a pond surface.
FiGuRE 17.1
A grading design for a pond
understanding Feature lines
In Chapter 4, you used survey figures to serve as breaklines in the EG surface.
For a design surface, you'll use
feature lines
for most of your breaklines. Survey
figures and feature lines are fundamentally similar: They are three-dimensional
linear objects that can be named, stylized, and shown in Prospector. The primary
difference is that you design feature lines, whereas survey figures are driven by
data collected in the field.
understanding Sites
When working with feature lines, you have to consider the use of
sites
. Feature
lines in the same site are “aware” of one another and will try to interact if the
