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| Deletions are marked like this. | Additions are marked like this. |
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| (Getting Started with ArcGIS p 50) | (Getting Started with ArcGIS starting on p. 50) |
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| ''Primary'' features in coverages are | '''Primary features''' in coverages are |
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| ''Composite'' features are built from primary features. | '''Composite features''' are built from primary features. |
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| ''Secondary'' features are | '''Secondary features''' are |
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'''Label points''' can represent individual point features (e.g. wells, intersections etc). The points ''label'' or ''link'' the attributes to polygons. Each polygon in a coverage has a single label point with its feature ID number, usually at the center. '''Arcs''' are connected sets of line segments, with nodes at the endpoints. Arcs can be organized into polygons that represent areas. '''Nodes''' are the endpoints or and connections between arcs. Nodes can have attributes so that they can represent point features in a network such as values in a network of water mains. Nodes are important because they connect "features" to each other. (form the topology???) '''Polygons''' represent areas bounded by arcs, including island polygons. We DEFINE polygons such that they do NOT OVERLAP. a point can fall into at most one polygon. |
Coverages
(Getting Started with ArcGIS starting on p. 50)
Coverages contain primary, composite and secondary feature types.
Primary features in coverages are
- label points,
- arcs, and
- polygons.
Composite features are built from primary features.
Secondary features are
- tics,
- links,
- annotations which are used to provide text about the geographic features on the maps.
Label points can represent individual point features (e.g. wells, intersections etc). The points label or link the attributes to polygons. Each polygon in a coverage has a single label point with its feature ID number, usually at the center.
Arcs are connected sets of line segments, with nodes at the endpoints. Arcs can be organized into polygons that represent areas.
Nodes are the endpoints or and connections between arcs. Nodes can have attributes so that they can represent point features in a network such as values in a network of water mains. Nodes are important because they connect "features" to each other. (form the topology???)
Polygons represent areas bounded by arcs, including island polygons. We DEFINE polygons such that they do NOT OVERLAP. a point can fall into at most one polygon.