Point cloud to CAD
Point cloud to CAD and DXF, from E57, LAS or PLY
Point cloud to CAD in Neurones 3D is one command: open an E57, LAS, LAZ or PLY scan, run Process › Floor plan…, and save the plan, sections and elevations as DXF R2000, SVG and PDF 1.4, lettered and scaled to ISO standards. It runs offline on your own Windows PC. DWG is not written.
By Dr. Florent Poux, 3D Geodata Academy · Updated
At a glance
Short statements, each one checkable. Where there is a number, it was measured, and the guides say on what.
- N3D reads E57 (multi-scan), LAS, LAZ, COPC, PLY, PCD and ASCII points, and an IFC model can be drawn too.
- One command, Process › Floor plan…, draws a plan per storey and automatic sections and elevations, with nothing traced by hand.
- The DXF is R2000: model space in metres at 1:1, real dimension entities, ISO 13567 layer names, pure ASCII with a declared code page.
- The SVG is in real paper millimetres with text kept as text; the PDF is 1.4, vector, at the sheet’s true size.
- Sheets follow ISO 3098 lettering, ISO 5455 scales, an ISO 5457 frame, an ISO 7200 title block and ISO 128 line weights, on A4 to A0.
- On S3DIS Area 4 (43 million points) it wrote the plan, six sections and elevations, 21 files and the GIS layers in 1.0 s.
- Wall thickness is within about ±30 mm at the default voxel on a real survey.
- DWG and DGN are refused: DWG’s specification is not published and the only open library is LGPL, which N3D’s permissive-only licence policy excludes; DXF R2000 opens in AutoCAD and every CAD package.
- Drawing and previewing are free and offline; saving DXF, SVG and PDF needs a paid edition, bought once.
How a scan becomes a CAD drawing
From E57 to DXF in one run
Open the scan with File › Open…: E57 with its multiple scans, LAS, LAZ, COPC, PLY, PCD or an
ASCII point file, from any scanner. A 127.8 million point, 7.9 GB E57 opens in about 22 s, and
the index is built with bounded memory, so a file larger than RAM still opens. Then choose
Process › Floor plan…. N3D decomposes the cloud, builds a scene graph, finds the rooms as
volumes of free space, extracts the walls between their two measured faces with their doors and
windows, and draws a dimensioned plan per storey with its sections and elevations. Choose the
sheet, the scale and the units, and press DXF, SVG or PDF. On S3DIS Area 4, 43 million
points, the whole set of 21 files and the GIS layers took 1.0 s. The same run is available
headless as n3d-render-cli floorplan.
What each file contains
| File | What is in it |
|---|---|
| DXF | R2000; model space in metres at 1:1; real dimension entities; ISO 13567 layer names; pure ASCII with a declared code page |
| SVG | real paper millimetres; text stays text |
| version 1.4, vector, at the sheet’s true size, with an embedded font when a name needs one | |
| GeoJSON, Shapefile | the building as GIS data; the Shapefile with its .dbf, .shx and .prj |
On every sheet the lettering is from the ISO 3098 series, the scale from ISO 5455, the frame per ISO 5457 with a 20 mm filing edge, the title block per ISO 7200, and pen widths and hatched poché per ISO 128. Dimension text sits above the line as read, per ISO 129.
Sections, elevations and quick slices
The floor plan’s sections and elevations are drawings: a cutting plane draws the walls it meets cut, in poché, with everything beyond in projection, and moved past the façade the same plane gives an elevation. For a quicker look, the 2D sections & floor plans tool in the toolbar cuts a horizontal slab or a vertical section at any angle, locks into an orthographic view you can measure in, and saves a PNG orthoimage up to 8192 px. That image is a picture of the points, not a drawing: nothing is extracted and nothing is dimensioned, so it is not a CAD file.
Why there is no DWG
DWG and DGN are proprietary binary formats. DWG’s specification is not published, and the only maintained open reader is LGPL; N3D ships only permissively licensed code, so it refuses both, on reading and on writing, and says so. DXF R2000 is the open exchange format that AutoCAD and every CAD package open, and N3D writes it with real dimension entities so the dimensions stay dimensions after import. Going the other way, N3D reads DXF fully: a design drawing can be laid over the scan in the same coordinate frame as a vector layer, and a DWG can be saved as DXF from the program that made it, or converted with the ODA File Converter.
Limits, stated
A wall the scanner did not see cannot be drawn. Wall thickness is as good as the decomposition voxel, about ±30 mm on a real survey. Wall ends are joined within 0.9 m, and a wall meeting another’s side within 2.2 m; wider gaps are left as surveyed. A sprawling space riddled with furniture is lettered Open plan rather than called a room. Levels are on the scan’s datum, with no field yet for a project datum. The drawing set is made for buildings; for a terrain survey, contours leave as GeoJSON or Shapefile, not DXF. For the plan itself, room by room, see point cloud to floor plan.
Questions
How do I convert an E57 point cloud to DXF?
Open the E57 with File › Open…, choose Process › Floor plan…, pick the view, storey, sheet, scale and units, and press DXF. Change the View to save each section and elevation the same way. A 127.8 million point, 7.9 GB E57 opens in about 22 s.
What is in the DXF?
A DXF R2000 file with model space in metres at 1:1, real dimension entities rather than exploded lines, and ISO 13567 layer names, written in pure ASCII with a declared code page. The drawing holds walls in poché between their measured faces, doors with their swing, windows with their glass, dimension chains, room labels with areas and levels.
Can N3D export DWG?
No. DWG and DGN are proprietary binary formats: DWG’s specification is not published, and the only maintained open reader is LGPL, which N3D’s permissive-only licence policy excludes. So N3D neither reads nor writes them, and says so. It writes DXF R2000, which AutoCAD and every CAD package open, plus SVG and PDF.
Can I get sections and elevations, not only a plan?
Yes. The same run places sections and elevations automatically where they cross the most rooms and openings, and the plan carries their marks. Each is saved as DXF, SVG and PDF.
Which scales and sheet sizes are available?
Sheets from A4 to A0 (A3 by default), a scale from the ISO 5455 series or fit to the sheet, and units in metres, centimetres or millimetres. Lettering is on the ISO 3098 series: 1.8, 2.5, 3.5 and 5.0 mm.
Can it turn a terrain scan into a DXF with contours?
Not as DXF. Contours are written as GeoJSON or Shapefile, and the terrain rasters as GeoTIFF or ESRI ASCII grid. The DXF drawing set is the floor plan’s.
Can I edit the drawing before exporting it?
Partly. Dimensions, room labels and marks can be dragged, notes added with a leader that snaps to a wall, and the title block filled in. Further editing belongs in CAD, which is what the DXF is for.
Is point cloud to DXF free?
Drawing and previewing the set are free, with no account and no trial clock. Saving DXF, SVG, PDF, GeoJSON and Shapefile needs a paid edition, bought once, with no subscription.
The guides behind it
Each guide gives the menu path, the steps, the command-line equivalent and the limits.