We are currently using the 'Designer defining nominal point' method for the development of a new product line. We are using this for PPAP design control only. What happens is the Designer defines a point cloud on the nominal 3D surface then applies a surface profile to the point cloud. These points then follow the development cycle of the part through to production then become the design control for the purpose of PPAP. We determine the locations of the nominal points through our SE meetings. The method of determining where the point will actually lie on the surface is determined from the input of the Manufacturing Engineer, Product Engineer, Product Designer, Tool Engineer, Product Supplier, Product Customer, and the Inspector. Actually, everyone in the SE group has input. The roll of the Engineering base is to illustrate what features are considered functionally significant by defining a point cloud on a particular feature. The inspector then determines the best location and number of points required to inspect the feature based on what engineering has said the functionality of the feature to be. Not only does the Inspector provide input on the point locations, but also the Tolerance to be applied to the feature. The Inspector provides the best input for the measurement systems that will be utilized to inspect the product. They also know the capabilities of the analysis systems that will be used to analyze the collected data. This allows them to apply the points and tolerance on the feature in a more cost effective manner, based on functionality and control intent. As you may see, the Inspector plays a major roll in Feature and Tolerance Management. It goes much deeper than this, but at least you have some idea of how we determine point locations.
Now, to the real question you asked, I have heard that there is a group that is trying to determine a 'best practice' for defining how best to measure any given feature on any given measurement system, but cannot at this time remember what group it is. I will track it down and post it next week. But, what it boils down to is experience and understanding the measurement systems capability.

Hope my Babble didn't cause confusion.

John Foreman
Chrysler, Kokomo Casting Plant