The Size command allows only one input feature at a time.
There's a difference in supported features in the different standards modes.
In the ASME Y14.5 mode, the valid input feature types are cylinders, circles, 3D widths, 2D widths, and spheres.
In the ISO 14405-1 modes, the valid input feature types are cylinders, circles, 3D widths, and 2D widths.
This difference is because ASME Y14.5 defines the unrelated actual mating envelope and the local size for all regular features of size. On the other hand, ISO 14405-1 is explicitly restricted to the "cylinder" feature of size and "two parallel opposite planes" and their cross sections.
Any input features that you use with the Size command should contain enough points to represent well the actual surface. To best mimic the intent of the standards, those points should be opposing points.
Limits on Input Features for Section Sizes
Several ISO specification operators for size are referred to as "section sizes". For example, "(GG) ACS" and "(LP) ACS (SX)" are section sizes. Section sizes are local sizes where each cross-section of the cylinder or of the 3D width has a size. Then, the worst section size is reported for each applicable limit.
One possibility for producing data in sections is to use 2D cross section features like circles and 2D widths. The other possibility is to use a measurement strategy that produces data in sections, such as "Default PC-DMIS Measurement Strategy" or "Adaptive Cylinder Concentric Circle Scan". For more information on measurement strategies, see the "Working with Measurement Strategies" topic in the "PC-DMIS CMM" documentation.
When evaluating the section sizes, the command partitions the data into sections, according to these rules:
For circle features and 2D widths, the command uses the data without partitioning, because the feature is already a cross section.
For cylinders, the command attempts to partition the data into circular cross sections. The data must be arranged in circles or the command will fail.
For 3D widths, the command fails.
When partitioning cylindrical data, the command first projects the points onto the cylinder's axis. It then identifies clusters of projected points as belonging to the same cross section.
