DEM to
contour lines, online

Upload a georeferenced GeoTIFF and export its contours as DXF, GeoJSON or SVG. No GIS to install.

Open the editor What's in the file

Works with

  • GDAL
  • QGIS
  • ArcGIS
  • AutoCAD

Your DEM,
traced in the browser

TopoLines

Upload, draw a zone, export. Your raster never leaves the server.

Open the editor

What's in
the file

  1. 01

    Contours at height

    DXF with 3D polylines, GeoJSON with elevation and type on every feature.

    QGIS 3.44 with the DXF and the GeoJSON exported from the same Navacelles zone: the DXF on its CONTOUR_INDEX and CONTOUR_INTERMEDIATE layers on the left, the GeoJSON in a second map view on the right, its attribute table listing elevation and type per contour
  2. 02

    The GDAL contour step

    Interval, index contours, simplification and a minimum length to drop noise.

    TopoLines Settings panel, 10 m interval, index contours on, simplification and minimum length, beside the contours traced from an uploaded GeoTIFF of the Cirque de Navacelles
  3. 03

    In your coordinate system

    UTM, Lambert-93, British National Grid… or WGS 84.

  4. 04

    Nothing shared

    The raster is traced on the server. Only the contours come back.

    TopoLines Map info after the trace: elevation 270 to 701 m, and Source reading Uploaded DEM · 2 m (RGEALTI_2m_Navacelles_LAMB93.tif)
QGIS 3.44 with the DXF and the GeoJSON exported from the same Navacelles zone: the DXF on its CONTOUR_INDEX and CONTOUR_INTERMEDIATE layers on the left, the GeoJSON in a second map view on the right, its attribute table listing elevation and type per contour
TopoLines Settings panel, 10 m interval, index contours on, simplification and minimum length, beside the contours traced from an uploaded GeoTIFF of the Cirque de Navacelles
TopoLines Map info after the trace: elevation 270 to 701 m, and Source reading Uploaded DEM · 2 m (RGEALTI_2m_Navacelles_LAMB93.tif)

From map
to file

TopoLines editor, search mode menu set to DEM upload; the footprint of the uploaded GeoTIFF, 18.88 km² around the Cirque de Navacelles, outlined as a zone on the map

A georeferenced GeoTIFF up to 200 MB. The map moves to its footprint.

From 5 to 100 m, with index contours. The preview redraws as you go.

GeoJSON for GIS, DXF for CAD, SVG for design.

No DEM?
Use ours

Draw a zone anywhere: the finest open model covering it is traced instead.

Contours of the Cirque de Navacelles (Gard/Hérault), 2.1 × 1.6 km, traced from IGN RGE ALTI at 1 m: 10 m interval, index every 50 m

National lidar. France, US, Switzerland, England and more, down to 1 m.

The same Cirque de Navacelles zone traced from IGN RGE ALTI at 5 m, the step a larger zone is served at: 10 m interval, index every 50 m

Sized to the zone. Finest on small zones, coarser on large ones, picked for you.

The same Cirque de Navacelles zone traced from the GEDTM30 30 m bare-earth model: 10 m interval, index every 50 m, smoother lines and less detail

30 m bare earth. GEDTM30 everywhere else, ground under the trees.

Elevation data

Sharper
where the data is

National 5–10 m models where they exist, a global bare-earth model everywhere else.

Bare earth first

Contours follow the ground, not treetops or rooftops.

Picked for your zone

Auto reads the finest source covering the whole zone.

Bring your own

Upload a georeferenced GeoTIFF and trace it like any zone.

Credited in the file

Source and licence are written into every export.

Other tools

AutoCAD 2027 with the Chamonix contours in 3D: one index contour selected, the Properties palette reading 3D Polyline on CONTOUR_INDEX, Z 2750 in the status bar
AutoCAD & Civil 3D A 3D-polyline DXF in your drawing's coordinate system.
TopoLines DXF of the Chamonix valley open in Rhino, with the contour layers in the Layers panel
Rhino & Grasshopper Curves at height for surfaces, scripts and the laser.
Sandbox terrain of the Chamonix valley in SketchUp, the contours coloured by tag on the mesh, Tags panel open
SketchUp From a DXF to Sandbox terrain.

Frequently asked questions

Formats, coordinates, data and pricing. More in the exports documentation.

Which DEM files can I upload?

A georeferenced GeoTIFF (.tif or .tiff) up to 200 MB: a lidar DTM from a national portal, a drone survey, or any elevation raster. Uploading is a Pro feature.

What do I get back?

Contour lines as DXF (3D polylines on layers), GeoJSON (each feature with its elevation and type: index, intermediate, auxiliary, coastline), SVG grouped by elevation, or PNG.

Is my DEM shared or stored publicly?

No. The raster stays on the server to be traced; only the contours you export leave it.

How does it compare with gdal_contour or QGIS?

It covers the same contour step: interval, index contours, simplification, minimum length and reprojection, without installing anything. For analysis beyond contours, a full GIS is still the right tool.

Is the export free?

No. The free account exports PNG; DXF, GeoJSON and SVG cost 1 credit for a zone under 10 km² (3 with national lidar). Packs start at €5 for 20 credits, never expire, no subscription.

What can't it do?

Replace a survey. The finest interval is 5 m, and the contours come from bare-earth terrain models: accurate to within a few decimetres to about a metre with national lidar, to a few metres with the 30 m worldwide model. A vector export covers up to 500 km² per zone.

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