In the utility network, elevation information is managed centrally via so-called survey points. These survey points form the binding basis for all elevation values in point, line, and area objects in the network. Each survey point is a simple point data set that contains the complete three-dimensional geometry (x, y, z), the elevation type according to SIA 4008 (KoteRef, KoteZ, or KoteAnnahme), position and elevation accuracies, and information on the recording method. In addition, SurveyPoints store a reference to the associated network object, depending on whether they belong to a point, line, or area element. Storing the source (e.g., field survey, construction, or import) and the capture date makes it possible to manage SurveyPoints in a targeted manner throughout the data lifecycle and to delete them if necessary.
The point and line objects of the network are extended by the attributes KoteRef, KoteZ, KoteAnnahme, and additional assumption attributes (e.g., Dimension_Annahme or Breite_Annahme). These fields are used to transfer Z values from the referenced survey points and enable consistent storage of elevation information directly on the feature without losing the original measured source.
During interactive capture or editing, a series of attribute rules ensures that SurveyPoints are automatically linked to network objects and that heights are transferred correctly. When a line or area is snapped to a SurveyPoint during digitization, the reference point of the line automatically adopts its complete x, y, and z coordinates. At the same time, an attribute rule enters the GlobalID of the line or area into the SurveyPoint so that the reference remains traceable in both directions. A similar behavior is provided for point objects: If a junction or device feature is captured on a SurveyPoint, it receives the geometry, elevation type, and accuracy information directly from the SurveyPoint, which in turn stores the GlobalID of the point object.
Users can either digitize lines directly or first capture individual SurveyPoints and then use them to construct the line. If there are several SurveyPoints with the same x/y position, users must select the desired point specifically so that it is clear which elevation value is to be used. If objects are created directly in the GIS without involving SurveyPoints, no SurveyPoint is generated.
Automatic validation of survey points plays a key role in data quality. A special rule regularly checks whether the referenced network data record still exists and whether its geometry still matches the SurveyPoint. If, for example, the position of the object no longer matches the associated survey point, the object has been moved, split, or merged—in this case, the SurveyPoint is automatically deleted to avoid outdated elevation data. This logic is particularly helpful for complex editing processes such as split and merge operations, in which parts of the geometry are assigned new GlobalIDs or merged. Optionally, the model can be extended to store split or merge flags or old object IDs if more detailed tracking is desired.
When editing the geometry in the normal way—i.e., when moving, breaking, or merging lines—existing SurveyPoints are deliberately not adjusted and no new ones are created. The reason for this is the expectation that elevation information can be linked back to the geometries via export or automated processes and that the user retains full control over the persistence of the SurveyPoints.
Overall, this model ensures that elevation values always come from a clearly defined and verified source, that their origin and accuracy remain traceable at all times, and that no outdated or inconsistent elevation information can arise in the database. The combination of the SurveyPoint class, extended attribute fields, and attribute rules ensures that elevation maintenance in the utility network functions robustly, traceably, and automatically, both during digitization and data-driven model maintenance.
A special case in modeling is the recording of arcs. While an arc is represented in a 2D map as a single point object connecting two lines, in a 3D representation it consists of two points at different heights: the lower and upper ends. There are two methods available for recording this.
The first option is simplified representation using a single point. The lines connected to this point automatically adopt its height. For example, if the arc is at an average height between the upper and lower pipes, the upper pipe is moved downwards and the lower pipe upwards in the 3D view so that both are at the same height at the arc point. This method is quick and easy, but can lead to an inaccurate representation of the actual pipe route.
The second, more accurate method is to capture the bend as a separate line element between two fittings, each with its correct Z-values. This preserves the actual height of the pipes and accurately depicts the bend in space. Although this approach is more labor-intensive, it provides more reliable 3D data and is particularly recommended for high-quality modeling.
