Identifier: polygon_validation
Identifier: polygon_validationsystem numeric
The level of validation checking done on new (or changed) polygon entities. The various levels are:
0 - Checks for coplanarity. All vertices should be in the same 3-D plane. Adjustments are made where necessary.
1 - Checks for coplanarity, coincident vertices and slivers.
2 - Checks for coplanarity, coincident vertices, slivers, crossovers and overlapping edges.
3 - Checks for coplanarity, coincident vertices, slivers, crossovers,
overlapping edges,
and checks for crossovers and overlapping edges between any
parent or child polygons.
The default value at system startup is 1.
No adjustments (other than for coplanarity) are made for invalidities found for levels 1,2 or 3.
The same checks are made using polygon_validation whenever a polygon's vertex list changes.
Note: Changing the value of this identifier will not perform validity checks on existing polygons, but only on subsequent new or changed polygons.
After validity checks, a polygon's vailidity may be examined by looking at its boolean attribute entity.valid.
If it is invalid, the reason for its invalidity may be examined via the attribute
entity.invalidity.
Manual validity checking may be performed
by using the validate command.
Here is an illustration for what constitutes an invalidity:
| 1 | Coincident vertices: |  |
Sliver: |  |
| 2 | Crossover: |  |
Overlapping edges: |  |
| 3 | Child crossover: |  |
Child overlapping edges: |  |