3.1. Break Line Definition

The options of this group of commands allow break lines to be defined if the tools available for exploiting code possibilities have not been used, which is generally advisable.

These comprise different tools to manually, automatically and semi-automatically define break lines, which will a priori generally have to form part of the obligatory lines used to form part of the digital terrain model either due to either the terrain’s characteristics or the specific way of viewing it. Defining them is not obligatory. However, it is highly advisable to ensure the work is valid and accurate, given that these lines define the relief marked by existing slope changes.

In this example, we can see how the surface adapts itself to the slope changes represented by the break lines, troughs, slope crowns or feet, construction lines, white road lines, etc.

Break lines are conventional CAD polylines that are defined on specific layers. These polylines’ vertices may or not coincide with surveying points. If they coincide on the ground plan, the triangulation considers the point’s height Obviously, if they do not coincide, the height of the polyline’s own vertex is taken.

These polylines can be drawn on the plan or the space, depending on whether the 3D Break Lines parameter is activated in the program’s configuration of the program, Utilities > Configuration > Surfaces. It is normally advisable to draw them in 2D, since all kinds of editing operations can be performed with the CAD commands, which would be more difficult in three dimensions. Additionally, these objects contain no additional information associated to them, so they can be treated by users as they wish. If the triangulation is defined and one wishes to include new break lines, the triangulation has to be repeated by selecting the layers where the break lines are found.

The application does not check if there are cuts in the break lines when it draws, so the user has to do so. In any case, triangulation cleanup commands have been implemented and they should be used to detect these cases. One example is the Check Break Lines command.