Geometric Control of Points with Point Measurements

Introduction

Geometric control against points is a direct deviation calculation between two coordinates.

In other words, we calculate the vector deviation between a measured point and a theoretical point (reference). The deviation is calculated using the formula Deviation = measured coordinate - theoretical coordinate. A deviation of e.g., +0.020m in the north direction means that the measured point is 2 cm north of the theoretical coordinate.

We can use the presentation rule Vector to get a presentation in plan and 3D.

Figure: A = Theoretical point, B = Measured point

Measured points should be compared with the nearest theoretical point either by comparing point ID (S_OBJID) or by searching within a given radius in 2D or 3D.

The theoretical points (setting out data) must be in a separate application layer.

We specify the tolerance requirement in the control, from Min. tolerance to Max. tolerance.

We can set different tolerances for 2D, Height, and 3D.

Control Results

Horizontal List Field

After the control is performed, the program outputs the result of the calculation in the layer with measured control points.

Example of results from a 3D control.

The following properties become available in the horizontal list field:

• DIFF_ERROR - the vector deviation
• D_EAST - the East component of the vector deviation
• D_NORTH - the North component of the vector deviation
• D_HEIGHT - the Height component of the vector deviation
• CONTROL_RESULT_3D - the control result of the point. If the deviation is greater than the tolerance requirement, we get an X in the column.

Report

We get a dedicated Excel report for the control.