While search regions are usually fixtured, step results are by
default produced with respect to the absolute coordinate system. It
is possible and sometimes useful to have the results of a step
returned relative to another coordinate system, frame, or
fixture.
Note that in Matrox Design Assistant, the terms "coordinate
system", "frame" and "fixture" are synonyms.
If you need metrology results relative to a certain position,
use the global
frame, which is a reference frame available in every
Metrology step. The global frame is set to the absolute
coordinate system by default. However, you can reposition the
global frame to a required position (a fixture on a part, a datum
in a reference drawing), and then retrieve results relative to the
global frame.
When you access metrology feature results, you can choose from 2
available result sets: RelativeToGlobalFrame and
RelativeToImage
(the default). RelativeToImage results are
relative to the absolute coordinate system.
Note that you should not use the global frame to set features or
search regions relative to a certain position; use fixture outputs
from other steps or local frames for this purpose.
In most other analysis steps (all but the
PatternMatching step and the
ModelFinder step), the frame used to return results is set
by the Output
coordinates input. The default output coordinate system is the
absolute coordinate system, but you can set it to any other
fixture.