Applying Precision

This adjustment recomputes the coordinates in the traverse based on direction and distance precisions you give it. Once computed, the traverse closure reports the errors based on this precision. The resulting direction and distance are also displayed in the Traverse View and will be printed in any traverse reports.

Raw Data

When TPC applies precision to a traverse that has not been adjusted, but has raw data, it applies precision to the raw directions and distances before it computes each foresight or sideshot.

Adjusted Data

When coordinates have been adjusted, precision is applied to the inversed azimuth and horizontal distance between the existing coordinate positions. These are then used to re-compute the point.  For grid traverses, the grid azimuth and distance are inversed. For geodetic traverses, the geodetic azimuth and distance are inversed.

Warning!! You can get different results (adjusted coordinates and closure) depending on whether you apply precision before or after adjusting coordinates. If precision is applied before coordinates are adjusted, the adjustments are based on the rounded raw data values and so the closure error will probably not be zero. If precision is applied after adjustment, the adjustment is based on the raw data and the resulting inverses are then rounded based on the precision.

Traverse Units

Beginning with TPC Desktop 2011, TPC applies distance precision based on the units of the traverse. To apply a precision of 1 link per the PLSS, first insure that the raw distance data in the traverse is in chains, then choose a distance precision of 0.01 chns.

The precision dialog displays units with the precision, as does the Adjustment Details section of the Closure View. So you will see 0.01 ft, 0.01 chns, etc. depending on the traverse units.

TPC also applies any elevation scaling before rounding. If for instance, you have selected a distance type of "Geodetic distance at mean project elevation (3500 ft) PLSS", the rounded distance based on precision willl also be a distance of this type.

Sticky Adjustment

TPC refers to Precision, Curvature & Refraction and Scale Factor as 'sticky' adjustments. You can apply sticky adjustments before balancing angles and coordinates. Sticky adjustments also remain in effect when you choose Tools | Recompute from the Traverse View.

Precision Report

Precision is reported in the Closure View and traverse reports as 'Precision: 10 min, 0.1 ft' with the direction precision followed by the distance precision.

Direction precisions display the value and units, like 1 degree, 1 minute, 10 seconds or 0.1 seconds.

Related Topics

Traverse Closure
Closure View
Apply a Scale Factor
Balancing Coordinates
Balancing Angles
Curvature and Refraction
Adjusting a Traverse
Sticky Adjustments


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