Geometric Accuracy Example(Cont’d)
If CAD-X sends the .003 mm tolerance value (uncertainty value in STEP) in the file then CAD-Y would be alerted that it may need to perform some operations , such as reintersect the edge curves e1, e4, and e5, or associated surfaces, in order to calculate a vertex point within .001mm of the edge curves.
The situation for edge curves that fail to be exactly on surfaces is more complex. Generally, surface-to-surface intersection algorithms require an iterative approach that converges on a solution. The 3-D points output will generally be on one surface and be within some tolerance of the other. The accuracy of that curve may be increased by increasing the density of the points output from the algorithm.