Find Gaps

Used to find empty space between the endpoints of two linear elements.

A gap is not the same as an extended intersection, which occurs when the minimum distance between the endpoint of one element is within the tolerance of another element.

Finding and repairing gaps is essential for creating area topology and linear networks. When endpoint gaps are repaired, the coordinates of all the endpoints within the gap tolerance are modified to have the same value. If there is a coordinate among the set of endpoints that occurs most frequently, it is selected as the new value; otherwise, the average point is used. For example:

The Find Gaps tolerance setting determines if an endpoint is to be fixed or flagged. For example, a tolerance setting of 5.0 would affect an endpoint gap of 4.0, but would not affect a gap of 7.0. For example:

Setting	Description
Mode	Determines how unconnected endpoints are handled. Flag Unconnected Endpoints - Places a circle flag on boundary endpoints that are not connected to other boundaries. The endpoint must be within the gap tolerance of another boundary's endpoint. Boundaries with unconnected endpoints are another way of saying dangles. Flag All - Locates endpoint gaps within a specified tolerance and flags them with a circle. Repair Unconnected Endpoints - Repairs only boundary endpoints that are not connected to other boundaries. The endpoint must be within the gap tolerance of another boundary's endpoint. Unconnected endpoints move to the closest connected endpoint within the gap tolerance. If there are no connected endpoints within the gap tolerance, then the endpoints of all unconnected endpoints are averaged. Repair All - Locates endpoint gaps with a specified tolerance and repairs them.
Tolerance	Defines the tolerance between element endpoints.
Facetize	Breaks the fence into a grid of cells. See Facetization for details.
Columns	Sets the number of cells (in the grid) that the fence is cut in the X or horizontal direction.
Rows	Sets the number of cells (in the grid) that the fence is cut in the Y or vertical direction.
Write Flags	When turned on, flags are written to the file, otherwise they are display only.
Level	Sets the target level of the flags.
Color	Sets the target level of the flags.
Weight	Sets the target weight of the flags.
Flag Radius	Determines the size of the circular flags placed at boundary endpoints within the gap tolerance of other element endpoints.

To Find Gaps:

Place a fence around the target linework.
Select the Find Gaps tool.
Select a Mode type.
Set Tolerance, Facetization, and Flag settings as appropriate.
Initiate the processing with a data point.
Review the content of the Results dialog.
The results can be saved or appended to a text file by selecting the appropriate option from the Results dialog File menu.

When gaps are repaired, circular arcs and curves are preserved as long as they are not part of a complex chain. Arcs and curves within complex chains are stroked before gaps are repaired. Since a new arc may have both its endpoints modified, the new arc is defined using the new endpoints and the mid-point of the original arc. This minimizes the displacement of the new arc with respect to its original position.

Note: Repairing gaps may create duplicate or similar elements. Elements shorter in length than the gap tolerance are removed.

Key-in: FIND GAPS