Hidden-Point Bar definitions are saved with the Users Options. Bars can be defined in either of three ways:
Gravity Frame. A gravity frame is a single point offset point. Added to support survey applications it can be used to com- pute the location of a point shifted a predefined distance along the Z axis of a reference frame.
2 Point Bars. Define the distance of a third point (C) based upon the vector between the two measured or selected points and the entered distance from one of those points (A or B) .
N-Point Bars or Fixtures. With 3 or more points defined, a 3D position can be computed anywhere in space relative to the measured or selected points. N-Point Fixtures are defined by selecting a set of points and also selecting a measurement lo- cation to return when those points are measured.
Automatic Hidden Point Computation
The most effective way to use hidden point bars or fixtures is to use a naming convention to designate points as part of a defined hidden point bar or fixture. To do so follow this naming convention:
point name $ (Bar index) _ (point index)
Point Name. The point name for the computed point should also be used for all the measurements of the reference points used to built it.
Bar Index. The Hidden Point Bars defined in the user options are not named but instead use an integer index. By specifying “MyPoint$0_0” you are specifying a point named “MyPoint” and telling SA to use the “0” index bar.
Point Index. Its important to specify a measured point as A or B for a 2 point bar to be computed correctly. Also the specific index of the points within an N Point Bar need to be defined. The final piece of the naming convention is the point index. So “MyPoint$0_1” tells SA to use the 0 index bar and that this point represents the “1” index point.
If this naming convention is followed hidden point locations can be updated/recomputed at any point by using the menu command Instrument>Instrument Shots>Compute Hidden Points. This can be quite helpful if hidden points are computed from multiple instrument plants and their relative positions are changed do to an alignment.