OpenCities Map Help

Create Shapes

The Create Shapes tool is used to construct simple or complex shapes from linear elements that share consecutive common endpoints and together define or infer a closed area. A newly created shape is a copy of the original line work. It is assigned the active line color, weight, and level.

To use this tool, the following must be considered:

  • Linear elements must not overlap or cross over themselves or other lines.
  • All lines must be segmented wherever they meet other lines. It is strongly suggested that unnecessary segmentation be avoided.
  • Boundaries must form closed networks to enable the inference of areas. Open junctions, dangles or duplicate linework are not permitted.
  • There should only be one linear element where a common boundary exists between two areas. A single boundary line that separates two coverage areas is associated with both areas. A boundary line for each coverage area is not needed. This helps minimize file size and eliminates problems associated with duplicate boundaries.
  • All linear elements should be area boundaries.
  • All areas within a single coverage must be exclusive and cannot overlap. Every point within a coverage theme falls unambiguously into only one area.
  • Each area must contain a centroid for a shape to be created successfully. A centroid is a single piece of text, text node, cell or point that defines the interior of an area. Only one centroid should be interior to a set of lines that would define a shape. A centroid often has a database linkage which defines the properties for the created shape. This database linkage would be used with the Associate Linkages tool.
Setting Description
Force Complex If on, a complex shape is created. A complex shape preserves the original linear elements as distinct elements.

If off, a simple shape is created. A simple shape is formed by combining several distinct linear elements into a single element. This occurs if the original linear elements that define the shape have less than 100 vertices. A complex shape is created if the original elements have more than 100 vertices.

Note: Centroids and boundaries are required to create shapes.
Note: Force Complex preserves the original linear elements as distinct elements.

To create shapes from boundaries and centroids:

  1. Place a fence around the source linework.
  2. Select the Create Shapes tool.
  3. If needed, enable Force Complex .
  4. Initiate the processing with a datapoint.
Key-in: FENCE CREATE SHAPES