Nested Polygons in Geodatabases

It is important to look at the calculations of plane area (called Shape_Area) and perimeter (called Shape_Length) for nested geodatabase polygons. Look at Figure 4-13, which has an island polygon D that has dimensions of 2 units by 5 units. Be sure you understand the area and perimeter calculations of polygon A, particularly with regard to the Shape_Area and Shape_Length.

FIGURE 4-13 A simple topological diagram in geodatabase form

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