Undershoots on map border check

The verification and editing of the metrics of linear and area objects are being performed. When checking a linear object, the first and last metric points are processed. When checking an area object, all metric points are processed.

The procedure for checking a point (P) that extends to the border (B) is as follows:

1. The distance (D) from the point to the sheet border is calculated.

2. If the distance «D» is greater than the value in the «Threshold for extending to border» field (d1), then it is considered that this point is far from the border. The point is skipped (no error).

3. If the distance «D» is less than or equal to the value in the «Threshold for extending to border» field, an additional check is performed (see points 4, 5).

4. If the distance «D» is less than or equal to the value in the «Threshold for alignment with the border» field (d2), then it is considered that point «P» aligns with the sheet border. The point is skipped (no error).5. If the distance «D» is greater than the value in the «Threshold for alignment with the border» field, point «P» does not align with the sheet border. An error message is recorded in the log: «Error in extending metric to sheet border». This scenario is illustrated in the figure.

During control in «Editing» mode, objects containing errors in extending to the sheet border are corrected. On zone boundaries, verification is performed using values of longitude of extreme meridians of zones.

Recommendations:

1. The value in the «Threshold for alignment with the border» field should be less than the value in the «Threshold for extending to border» field.2. It is not recommended to increase the «Threshold for extending to border» by more than 0.1 mm, especially in «Editing» mode. Increasing this threshold may cause unnecessary contour points far from the border to be extended.

3. By default, the «Threshold for alignment with the border» field has a value of 0.01 mm. Decreasing the value in this field allows for more thorough control of extending points to the border. For example, if a distance of 0.001 mm between linear or area object points and the border contour is detected, it is recommended to set the «Threshold for alignment with the border» to 0.0001 mm.