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Coordinate Observations

When using CPOS and RTK, you now often get observations of coordinates directly, without these coordinates being connected in a network as with traditional adjustments. When you have multiple measurements of the same point with standard deviations and correlations between x, y, and height, you can still run an adjustment of the coordinates and provide a quality measure of how good these measurements are.

Procedure for Processing Coordinate Observations

Procedure

  1. Import coordinates
  2. Possible transformation of correlations and standard deviations to the map plane
  3. Control of measurements
  4. Analysis
  5. Adjustment calculation

Import of Coordinate Observations

When importing coordinate observations, coordinates with associated standard deviations and correlations are imported. You currently have the option to import individual point observations from KOF format.

See Import from Field Book.

Transformation of Geocentric Values

In KOF files, the values for standard deviation and correlation can be given both in relation to coordinates in the map plane and in relation to geocentric coordinates. If they are given in relation to the geocentric system, a transformation to the current coordinate system is performed when importing into the surveying application layer.

Important Information About Coordinate System

It is important that the correct coordinate system is selected for the project. This is crucial for the transformation to produce correct values as a basis for the adjustment.

Control of Measurements

Before performing adjustment calculations, you should control the observations that have been imported into the project. In the list window for coordinate observations, a radio button Control is defined, which provides a list window specifically designed for such control. Values found here are time, PDOP, number of measurements, number of satellites, and time differences from other measurements of the same point. To check time separation for one point, you can first sort by time and then by PointID. Any measurements that do not meet the requirements should be removed here.

You should also control the imported standard deviations to ensure they are realistic. You have the option to correct these by manually scaling them with the replace function or calculating them from instrument parameters. This is done by selecting all observations, right-clicking, and choosing Calculate Standard Deviation from Instrument. If you want to get the original data back, simply run a new transformation. Select all observations, right-click, and choose Transform Observation w/ Standard Deviation.

Analysis and Adjustment of Network

In both the analysis functionality and adjustment calculation, parameters are calculated from the observations associated with points in the selection. This affects which test values are used in analyses and calculated error ellipses in adjustment. You must be aware of this - all points in the selection are run as calculation of one network. If it should be run for individual points, this is done through selection.

Adjustment Calculation

Coordinate observations can be adjusted together with other types of observations. See also Adjustment Calculation.