The Hidden-Point Bar Database
Hidden-Point Bar definitions are saved with the Users Options. Bars can be defined in either of three ways:
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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.
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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) .
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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)
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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.
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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.
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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.