Reduce Contour Vertices
Function
Contouring and smoothing often creates an explosion in file size due
to the many vertices it
adds to the individual contour polylines. Fortunately, many of these
vertices are very close together, some of which can be removed with no
visible effect on the contour polylines themselves. Reduce Contours Vertices can reduce
the total number of vertices up to 90%. This has the benefits of a
smaller drawing file, faster
drawing loading, and faster regens.
This command removes vertices in a polyline that are within a user
specified
offset cutoff. The algorithm looks at three vertices at a time, and
calculates the distance between the second
point and the line from the first to the third point. If this distance
is less than the user specified
cutoff, the second point is removed. In theory, reducing the polyline
vertices should not shift the
polyline more than the user's cutoff distance. The default for this
cutoff is one tenth of a foot.
Increasing the cutoff will remove more vertices while decreasing it
will more closely preserve the
original contour line. When combining vertex reduction with smoothing,
it is suggested to smooth
before reducing, although it can be done the other way around.
|
Original
Contours with 98 Vertices |
|
Original Contours Reduced by .5,
50 Vertices |
|
Smoothed
Contours with 540 Vertices |
|
Smoothed
Contours Reduced by .1, 194 Vertices |
|
Smoothed
Contours Reduced by .5, 88 Vertices |
|
Smoothed
Contours Reduced by 4.0, 39 Vertices |
Pulldown Menu Location: Surface > Modify Contours
Keyboard Command: reduce
Prerequisite: Create Contour lines to reduce.
File Names: \lsp\scadcntr.dcl, \lsp\scontour.lsp,
\lsp\reduce.arx