For surveyors, architects, land surveyors and engineering offices
📐 Pro topo in the browser
A more accurate GPS point by averaging measurements, a long profile drawn on the map, and earthwork volumes (cut / fill) with contour lines from a set of points, exportable to DXF.
Keep the phone still on the point (on a pole or on the ground), under open sky. Positions are recorded for the chosen duration, outliers are discarded, then the accuracy-weighted mean is computed.
Saved points (on this device)
| Name | Lat / Lon | UTM | Z | 2DRMS | Actions |
|---|
Honestly: a phone usually gives 2 to 5 m of real accuracy. Averaging reduces measurement noise, not systematic errors (reflections off buildings, obstructions). Centimetre accuracy needs an RTK GNSS receiver. GPS altitude is approximate (often ± 5 to 15 m).
Tap the map to draw the axis (road, canal, pipe, hike). The profile is computed on the Copernicus GLO-90 digital elevation model.
The elevation model has a 90 m grid and a vertical accuracy of a few metres: perfect for a preliminary study or a hike, not for detailed design. The route coordinates are sent to Open-Meteo to get the elevations.
Paste a set of surveyed points (one per line: "name X Y Z" or "X;Y;Z"), or import a CSV / TXT file. The terrain is triangulated (TIN), then compared with a reference level.
The volume is exact for the triangulated surface: its correctness depends on point density and on break lines (ridges, toes of slopes). Always check with your professional software before a contractual measurement.
My apps for surveyors and architects, before everyone else
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Join the clubGeodesy: GeographicLib (MIT). Triangulation: Delaunator (ISC). Map: © OpenStreetMap contributors. Elevations: Open-Meteo, Copernicus DEM GLO-90 model (© DLR, Airbus, ESA).