Elevation query
Retrieve terrain elevations for all network nodes from an online elevation service and apply them as z-coordinates
Overview
The elevation query automatically assigns terrain elevations to all nodes of the active network. To do this, the node coordinates are sent to an online elevation service and the returned elevations are applied as z-coordinates. The elevation profile is a prerequisite for a realistic calculation of the geodetic pressure heads in the network.
How to open
The 
Query elevations button in the Topology editing group - 
Network tab, General & topology page.
Prerequisites
| Prerequisite | Explanation |
|---|---|
| Valid coordinate origin | The project must be georeferenced (coordinate origin with UTM zone). The origin is set automatically when importing OpenStreetMap or GIS data, but can also be defined manually. |
| Internet connection | The elevations are retrieved from an online service (Mapy.cz Elevation API). |
Procedure
- VICUS Districts converts the position of each network node via the coordinate origin into absolute UTM coordinates and from there into geographic latitude and longitude.
- The coordinate list is sent to the elevation service; a progress dialog (Retrieving elevation data.) shows the ongoing retrieval.
- The smallest returned elevation is set as the new z-height of the project origin. Each node receives its elevation relative to this minimum as its z-coordinate:
- All remaining networks in the project are corrected by the origin shift so that they retain their absolute elevation.
- After successful completion, a confirmation message appears.
The change is recorded as a single undo step (Updated elevation data.) and can be fully reverted with Ctrl+Z.
Error cases
| Message | Cause and remedy |
|---|---|
| No valid coordinate origin set | The project is not georeferenced. Import OpenStreetMap or GIS data or set the coordinate origin manually. |
| Error in coordinate conversion | The computed latitudes/longitudes are invalid - check whether the origin coordinates and UTM zone are set correctly. The message names the affected node with the computed coordinates. |
| No elevation data could be retrieved from the server | No connection to the elevation service - check the internet connection; details may be in the attached error message. |
Checking in 3D
After the query, a visual check is worthwhile: leave 2D mode or rotate the view to check the elevation profile of the routes spatially. Outliers (e.g. from nodes on bridges or in excavation pits) stand out immediately in the side view.
Practical tip:
Run the elevation query only once the topology is essentially in place - that is, after Create intersections and Connect consumers. This way the automatically inserted branch nodes (mixers) also receive a correct terrain elevation. On topographically varied routes, the geodetic pressure heads have a major influence on the worst point and the required pump head.