Costly site visits
For a first site assessment — feasibility, quoting, slope study — a full topographic campaign is often disproportionate: travel, equipment, delays.
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Online topographic survey, built on IGN data
Enter a cadastral reference: GeoAlt assembles the LiDAR HD point cloud, the contour plan and the elevation report for your parcel.
A topographic survey describes the relief and land cover of a site: elevations, slopes, buildings, vegetation, parcel boundaries. GeoAlt produces it entirely online from public IGN data — LiDAR HD for relief, RGE ALTI for digital elevation models, the cadastre for boundaries — with no site visit.
What usually gets in the way
Underused public data
The IGN LiDAR HD program covers a large part of France with a classified point cloud, and RGE ALTI provides elevation models nationwide. Exploiting them takes GIS tooling and time.
Deliverables you cannot use as-is
Raw tiles cover square kilometres: the data must be clipped, classified, projected and formatted before it serves a project.
What GeoAlt delivers
- LiDAR point cloud clipped to your parcel
- The LiDAR HD cloud is extracted over the exact parcel boundary, with the useful classes: ground, buildings, vegetation. Delivered as LAS, E57 or XYZ, ready for your software.
- Plan with contour lines and sections
- The PDF plan overlays the cadastral boundaries, contour lines and elevation points; sections follow the real terrain profile.
- Elevation and constraints report
- Minimum, median and maximum elevations, slopes, built footprint: the report gathers the figures an study needs, with their sources.
- Exports for the rest of your pipeline
- DXF 3D for CAD, OBJ and STL for 3D, IFC for BIM, SVG for layout: every deliverable is one click away.
See the workflow on real data
The public demo runs the same engine on a real parcel: selection, LiDAR extraction, plan and exports.
Open the demoSupported formats
- Point cloud: LAS, LAZ, E57, XYZ
- CAD: DXF 3D, survey DXF, SVG
- 3D / BIM: OBJ, STL, IFC
- Documents: PDF plan, PDF report, CSV
Stated technical limits
- Vertical accuracy follows IGN LiDAR HD (a few centimetres on bare ground, less in dense vegetation).
- LiDAR HD coverage is progressive: some municipalities are only covered by RGE ALTI (1 m grid, no object classification).
- A survey built on public data does not replace a licensed surveyor’s regulatory measurement for boundary staking or easements.
Frequently asked questions
How accurate is the survey?
On bare ground, IGN LiDAR HD offers vertical accuracy of a few centimetres. On vegetation and roofs, accuracy depends on point density and classification. GeoAlt displays the source and date of every dataset used.
Is my municipality covered?
LiDAR HD coverage progresses by geographic blocks. Outside coverage, GeoAlt falls back to RGE ALTI (1 m digital surface model): relief stays available, without fine object classification.
How fast is the survey ready?
Extraction, contour computation and deliverable generation run on demand: a few minutes for a standard parcel.
Can I use the survey for a building permit?
The data serves to prepare the graphic documents (site plan, sections). The regulatory pieces of the application remain the owner’s responsibility and, where applicable, the architect’s.
Start your topographic survey
Enter a cadastral reference or draw your boundary: the cloud, the plan and the report are generated on demand.
Open the application