STAR*NET V6 - Circe
STAR*NET V6 - Circe
STAR*NET V6 - Circe
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Chapter 8 Analysis of Adjustment Output<br />
The next section shows the error ellipses and elevation confidences computed using the<br />
confidence level you chose in the project options. The error ellipse parameters define the<br />
shape and size of the confidence region around each station. In the output below, for<br />
example, you can say with 95% certainty the adjusted station lies somewhere within the<br />
ellipse region.<br />
Station Coordinate Error Ellipses (FeetUS)<br />
Confidence Region = 95%<br />
Station Semi-Major Semi-Minor Azimuth of Elev<br />
Axis Axis Major Axis<br />
1 0.00000 0.00000 0-00 0.00000<br />
2 0.05980 0.04579 29-17 0.07472<br />
3 0.06722 0.05219 159-23 0.07510<br />
Station Error Ellipses (3D Example)<br />
If the adjustment passes the Chi Square test, the adjusted coordinate standard deviations<br />
are used to compute the error ellipses directly. However, if the adjustment fails the Chi<br />
Square test, the standard deviations are increased by the computed Total Error Factor, to<br />
reflect the weak adjustment. This is done to protect you from generating artificially small<br />
ellipses by reducing your global observation standard errors to the point where the<br />
adjustment is no longer valid.<br />
The last section resulting from error propagation shows relative ellipses and a vertical<br />
difference confidence. By default, relative error ellipse information is computed between<br />
each station connected by an observation. Alternately, the “.RELATIVE” inline options<br />
can be used to control exactly which ellipses to compute. Relative ellipses provide an<br />
estimate of the accuracy of the relative positions of two stations. Two stations can have<br />
large error ellipses but a small relative ellipse between them, if their positions are highly<br />
correlated. Note that relative ellipses are also inflated by the Total Error Factor if the<br />
adjustment fails the Chi Square test. For detailed information on ellipse and relative<br />
ellipse interpretation see the next section.<br />
Relative Error Ellipses<br />
Confidence Region = 95%<br />
Stations Semi-Major Semi-Minor Azimuth of Vertical<br />
From To Axis Axis Major Axis<br />
2 13 0.06135 0.03833 63-47 0.06248<br />
4 15 0.07709 0.05626 54-01 0.09281<br />
2 19 0.07856 0.06761 170-50 0.04554<br />
Relative Error Ellipses (3D Example)<br />
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