WMS:General Coverage

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Sometimes which coverage attributes to use is uncertain, especially when importing a layer from another source (GIS, CAD). The general coverage provides a way to examine feature objects when the attributes are uncertain or unknown.

The general coverage allows creating or editing points/nodes, arcs, and polygons without defining attributes or worrying about special rules associated the different coverages and attributes. For examples WMS requires that stream and time computation arcs be defined from downstream to upstream, with the general coverage the direction of the arc does not need to be considered. Later, these feature objects can be converted to other coverages or data types.

When importing data from another source, there is no guarantee of the ordering, and if importing them to a drainage coverage type, it may cause problems. Therefore, import them to a general coverage, make appropriate edits (streams can be reordered by selecting the downstream most point and choosing the Reorder Streams command from the Feature Objects menu), and then convert the coverage to a drainage type.

Specific attributes cannot be assigned to feature objects in a general coverage. Arc elevations can be set as well as specific elevation values for nodes and vertices. Projections can also be defined for a general coverage.

After setting up the feature objects, change the coverage to another coverage type by right-clicking on the coverage and selecting a new Type. Convert a general coverage to another data type (TIN, 2D grid, etc.) using the standard map module conversion processes.


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