I have mentioned before how the Ring Orientation for the exterior ring of a Polygon is significant when instantiating a SqlGeography object. In this case, a Counter-Clockwise orientation is required so that as an observer walks along the path, the interior of the Polygon is always to their left.
But, what I have never really seen documented (or paid attention to, at least) is the fact that the interior rings, or holes, of a Polygon also have specific Ring Orientation requirements.
In keeping with the "Left-handed" rule, interior rings must be defined in a Clockwise manner - the opposite orientation of the...
A Ring is a list of points such that the starting point and ending point are the same (forming a closed shape). The order the you define the points that make up a Ring - known as Ring Orientation - is significant, for various data formats (including SQL Server's Geography type) imply special meaning for rings that are defined in a clockwise manner as opposed to a counter-clockwise manner.
Given a list of points with no additional context, it can be difficult to determine the Ring Orientation being used.
For example, suppose that you have a generic list of points that...