To Find Sliver Polygons

A sliver polygon is very long and thin; its perimeter is very large compared to its area. When overlaying two topologies, AutoCAD Map 3D toolset checks for sliver polygons. When creating a new polygon topology, checking for sliver polygons is optional.

To find sliver polygons when you create a polygon topology

  1. Follow the basic steps to create a polygon topology.
  2. In the Create Polygon Topology - Set Error Markers dialog box, select the option for checking for Sliver Polygons.
  3. Do one of the following:
    • To highlight errors with red Xs, select Highlight Errors.
    • To mark errors with blocks of the shape and color you specify, select Mark Errors With Blocks.

      In the Marker Size box, specify the marker size as a percent of the screen size. A value between 3% and 7% is usually suitable. Specify the shape and color of the block to use to mark each error.

  4. Click Finish to create the polygon topology and locate sliver polygons.

    To remove highlighting, use the REDRAW, REGEN, or SAVE command. To remove an error marker, select it and press Delete.

To find sliver polygons when overlaying two topologies

  1. In Map Explorer , under Current Drawing, right-click the source topology AnalysisOverlay.
  2. In Topology Overlay Analysis - Analysis Type, select Identity as the type of overlay analysis to perform. Click Next.

    The result topology includes areas that appear in the source topology and areas in the overlay topology that are within the source topology boundary.

  3. In the Topology Overlay Analysis - Select Overlay Topology dialog box, select the polygon topology to use as the overlay topology. Click Next.
  4. In the Topology Overlay Analysis - New Topology dialog box, do the following:
    • Select Highlight to highlight the resulting topology on screen. Select the highlight color.
    • Enter a name and description for the new topology, and specify the layer to place it on.
    • Click Next.
  5. If desired, specify how to copy data to the result topology, whether to create new nodes to complete the resulting topology, and the block to use for centroids.
  6. Click Finish.

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