2011

An example of network topology is a water-distribution application that traces
the flow of water from a pumping station to residences. A street network is
another example. For network topologies, you can specify the direction for a
link and specify the resistance for a link or node.
Polygon Topologies
■ Define polygons that represent enclosed areas such as land parcels and
census tracts. A single link defines the common boundary between adjacent
areas.
Uses of polygon topology include tax assessment and land planning in which
parcels of land are represented by polygons. Political boundaries, such as
voting districts, city, state, or provincial boundaries, special districts, and
school districts, are other examples of the use of polygon topology.
Notes
When you create a topology, keep the following points in mind:
■ Before you create network or polygon topologies, use the drawing cleanup
tools to
clean up your map (page 765). Node topologies do not usually
require cleanup.
■ Before you create a topology, freeze all layers containing objects in paper
space (Layout tab). Otherwise, these objects are included in the topology
creation when you use the Select All objects option.
■ MAPTOPOCREATE can create topologies on layers that are turned off. It
does not affect layers that are frozen.
■ When creating network or polygon topologies, if you enable the Create
New Nodes option, AutoCAD Map 3D detects where lines are connected
and assigns nodes to end points. It creates physical or explicit node objects
at all link end points where no objects exist. If the layer you specify does
not exist already, AutoCAD Map 3D creates the layer with a color of 7 and
a CONTINUOUS linetype.
■ You can create nodes using ACAD_POINT. To change their appearance
and size, at the Command prompt, enter ddptype.
■ When you create a topology, information is stored as object data on each
element of the topology and is saved with the map. Each node, link, or
polygon is automatically given a unique identification (ID) number. Each
ID is automatically processed when you use any topology command.
Creating, Editing, and Managing Topologies | 823