STAR*NET V6 - Circe

Appendix C Additional Technical Information
Since slope distances and zenith angles are both “sloped” observations, their total
standard errors are each inflated by both horizontal and vertical centering errors.
In the following formulas:
d = Horizontal distance from instrument to target
s = Slope distance from instrument to target
e = Elevation difference from instrument to target
Slope Distances: The total standard error is equal to:
Total Dist StdErr = Sqrt( DistStdErr 2 + (d/s) 2 * (I 2 + T 2 ) + 2*(e/s) 2 * V 2 )
Zenith Angles: The total standard error is equal to:
Notes:
Total Zenith StdErr = Sqrt( ZenithStdErr 2 + (e/s) 2 * (I 2 + T 2 ) + 2*(d/s) 2 * V 2 )
1. The calculations for angle and direction centering error in the formulas shown on
this page and the previous page are carried out in radians.
2. In any formula shown above for a linear observation (slope distance, horizontal
distance or delta elevation), the resulting “total” standard error is calculated from the
entered standard error of the observation plus any given centering errors. It should be
noted that the “entered standard error” for any linear observation is made up of a
constant part and PPM.. See the discussion of the PPM (Parts per Million) settings
starting on page 23 of Chapter 4, “Options.”
3. When standard errors are explicitly entered on an observation data line, these values
are by default used as the “total” standard error value that will be used during the
network adjustment. They will not be inflated by centering error.
If there are situations where you would like explicitly entered standard errors to be
inflated by entered centering errors, you can use the “.ADDCENTERING” inline
option as described on page 91 in Chapter 5, “Preparing Data.”
4. Centering errors are not applied to differentially leveled elevation differences.
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