2011

■ Representation of node, network, and polygon topologies
If possible, plan on completing all digitizing for one map in one session because
the map media may distort over time.
Digitizing Linear Objects
Linear objects are objects such as lines, arcs, and polylines.
■ If you plan to use topography later to generate 3D views from digital terrain
models, place linear objects at the elevations (Z- values) they represent.
■ If you use the SKETCH command to trace an irregular line, make sure the
variable SKETCHINC is set to a reasonable value, because each line segment
ends at the interval set by SKETCHINC. The SKETCH command can create
huge files for one small line when SKETCHINC is set to a small value.
■ When digitizing irregular curves with PLINE or
MAPDIGITIZE (page 1081),
the spacing of the selected vertex points should depend on the curvature
of the line. Straighter segments require fewer points.
Examples of digitized curves
■ However accurately you work, you lose data when you digitize a curve.
You need to digitize more points when you create sharp curves to ensure
that the line is as accurate as possible; however, while you reduce the data
loss, you increase file size and complexity. If you know the parameters
used to define a regular curve, such as the radius or length, use the Arc
option of the PLINE and
MAPDIGITIZE (page 1081) commands for digitizing.
Irregular lines, such as topography contours, should be continuous
polylines. They can be smoothed with the Fit option of PEDIT if necessary.
Set the PLINEGEN system variable to 1 (on) before digitizing, so that any
dashed linetypes are evaluated correctly.
1076 | Chapter 6 Creating and Editing Data