Building Face Survey
Chapter 12
One unapparent restriction is that the three points cannot be in a line. If the points are linear, you will see the warning message Linear and the Type field will display No solution.
The second major difference of a nonvertical plane is the method used to determine a local coordinate system. The first point is still the origin of the local coordinate system; however, the second point defines due east, not positive east, as with a vertical plane. The instrument station is still assumed to have a positive elevation in the local coordinate system, as it does with vertical planes. Once the plane has been defined, and you understand how the local coordinate system works for nonvertical planes, picking up detail observations is the same as for vertical planes.
SRX
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