Читать книгу Designing Geodatabases for Transportation - J. Allison Butler - Страница 51

If all you really need to do is make maps with your transportation geodatabase, then you should use a design that emphasizes the structure and attributes appropriate to such an application. Such a database would include annotation classes in addition to the feature classes of a facility inventory.

Figure 4.12 From the set of thematic layers described in chapter 8 of Designing Geodatabases: Case Studies in GIS Data Modeling, by David Arctur and Michael Zeiler (ESRI Press 2004).

The top part of this transportation mapping database is intended to support the editing process. It contains all the elemental pieces of the highway mode of travel like you may have in a normal segmented data structure of the type discussed above. These four feature classes exist in a transportation topology that will help ensure that clean linework is produced.

The bottom part of the database contains the classes that will be used to produce the maps. The RoadsCartoDissolve feature class contains the results of merging the various road segments in the MajorHwy, Ramp, and Road feature classes to produce the highway facility linework for our maps. This intermediary has been added to the mapping process in order to provide complex geometry. For example, you may want to outline major highways in black with a red center fill, or outline unpaved roads in black and use a white center fill. You cannot get this appearance through line styles applied to a single feature class. What you will need to do is produce a wide black line and overlay with an identical, but slightly narrower red or white line. This means printing two copies of the road features with slightly different line styles. It also means merging linear features so that intersections look outlined rather than overlapping. A valid values table (RoadsCartoDissolve_VVT) says which combinations are legitimate.