GGU-GEO-GRAPH: "Manually" menu item
Generally, the automatically generated triangle mesh is very high quality. However, there are cases in which you might want to generate a different interpolation between individual points. Using this menu item, you can create a triangle mesh completely by hand or rework an existing mesh. A message box provides information on the procedure:

To define a triangle mesh (interpolation mesh) the data points (measurement points) are first displayed in their correct locations.
If no points are visible, got to the "Page size + margins/Auto-resize" menu item or use the [F9] function key.
Then click three data points with the left mouse button; these then represent an interpolation triangle. Repeat this process until all the required data points are integrated into the triangle mesh.
The triangles may not overlap as this will almost always lead to nonsensical contours. You can have this condition tested by the program by going to the "Graphics/Test" menu item.
If you want to delete an existing triangle, click the points of the triangle once more. By pressing the right mouse button you can reset a triangle.