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Detail Calculation

A detail point is a sighting point that does not have known coordinates in all existing dimensions. This is an unknown point that has not been observed from, or that constitutes the endpoint in a one-way traverse.

Point status is D and the symbol is as shown below.

Detail point

Applications

Typical examples include polar measurements of:

  • Property boundaries
  • Utilities
  • Terrain features
  • Other objects measured from one station

A detail point is essentially a point where no specific requirements are set for quality or verifiability, meaning simple measurements for point calculation.

Info

The accuracy of detail points is estimated based on the assumed measurement accuracy of the instrument used.

Whether the detail calculation is performed in horizontal plane, height, or 3D is determined by the selected calculation type. This is chosen each time you run a calculation.

Limitations and Requirements

  1. Observations must not be made from the detail point. This means that selected points must have DETAIL POINT status.

  2. The station point must be known in the horizontal plane. This must be calculated first if it is not initially known, usually by means of an adjustment. If height is to be calculated, the station point must also be known in height.

Note

For detail points to be calculated in height, the following requirements must be met:

  • Vertical angle is measured to the detail point (from the known point/station)
  • Target height and instrument height are specified for the station and observation respectively
  • The station point has known/calculated height
  • The detail points have preliminary height values

Observations Included in the Calculation

The following observations are included in the detail calculation:

  • All distances and directions from known points to selected points
  • Other directional observations in the set if they go to known points
  • Vertical angles from known points to selected points, provided that:
  • The known point has a known height
  • The selected point has a preliminary height
  • Target height and instrument height are specified

Calculation Process

When you start a detail calculation, it follows these principles:

  1. Calculates preliminary coordinates for the unknown points
  2. Identifies all observations that can contribute to determining the detail point
  3. Performs adjustment calculation using the least squares method collectively for the selected detail points
  4. Estimates standard deviations for the detail points based on assumed measurement accuracy

Warning

It is usually not possible to perform an analysis of detail points, as there are no redundant measurements. This means that any errors in the measurements cannot be detected through the calculation.

Tip

To achieve higher reliability, a detail point can be measured from multiple stations. In such cases, the point should be changed to an adjustment point.