ALKIS NAS to DXF Converter
Converts an ALKIS NAS file (.xml) to a DXF drawing with one layer per ALKIS object type.
Upload one unzipped ALKIS NAS file (.xml, up to 50 MB). The worker reads it with GDAL's NAS driver and writes a single DXF file for CAD programs: every ALKIS object type lies on its own DXF layer named after it (for example AX_Flurstueck or AX_Gebaeude), areas are closed polylines and the drawing units are metres.
Drag a file here to convert, or select file
Accepted: .xml · max. 50 MB
What the converter does
- The file is checked and read as on the ALKIS NAS to GeoPackage converter: GDAL's NAS driver (-if NAS), coordinate system from the NAS header.
- GDAL's DXF driver writes a single layer; the DXF layer of each drawing object comes from the field Layer. The worker therefore collects all object types in an intermediate GeoPackage and joins them with a VRT union that fills Layer with the name of the object type.
- Areas such as parcels and buildings are written as closed polylines (LWPOLYLINE), not as hatches (GDAL option DXF_WRITE_HATCH=NO). Points stay points.
- The DXF header declares metres ($INSUNITS=6, $MEASUREMENT=1). GDAL's own template would declare inches, and CAD programs that evaluate this would read the metre values as inches.
- Coordinates are not changed. They stay in the coordinate system of the NAS file (in the test EPSG:25832, first vertex E 372210.782, N 5709971.700); the DXF itself stores no coordinate system.
- Only geometry and layer name are written, because DXF has no attribute table. Object types without geometry (for example AP_Darstellung) are not included; the report lists them.
- The report below the upload shows the DXF layers with the number of drawing objects, the notes and the exact commands.
GDAL command the worker runs
AX_Flurstueck stands for the object types in your file; the worker lists all of them in one call (e.g. AX_Hafenbecken AP_PTO AP_Darstellung). -a_srs is only added when the header names ETRS89_UTM32 or ETRS89_UTM33. nas_layers.vrt is a VRT union written by the worker: one OGRVRTLayer per object type with geometry and SourceLayerFieldName=Layer. dxf_header_metres.dxf is GDAL's DXF header template with the units set to metres.
Tested with
| Test file | Result |
|---|---|
| 40 parcels (AX_Flurstueck) from Herne, 275 KB | Layer AX_Flurstueck with 40 closed polylines; first vertex 372210.782 / 5709971.700 as in the NAS file |
| 40 buildings (AX_Gebaeude) from Herne, 358 KB | Layer AX_Gebaeude with 40 closed polylines |
| 7 harbour basins (AX_Hafenbecken), 1 label (AP_PTO), 1 AP_Darstellung, 103 KB | Layers AX_Hafenbecken (7 closed polylines) and AP_PTO (1 point); AP_Darstellung has no geometry and is not included; the text "Hafen" of the label is not in the DXF |
| All three DXF files in QCAD 3.33.1 | Opened without errors or warnings; layers and numbers of drawing objects (8, 40, 40) as expected; buildings and harbour basins drawn as closed outlines |
Tested on 28 Sep 2026 with the worker code of this site in the worker image (Debian, GDAL 3.10.3) on Fly.io's build server; the DXF files were opened in QCAD 3.33.1 (portable trial version). Test data: OpenGeodata.NRW, Grundrissdaten (NAS), package Herne, as of 2026-07-28, licence dl-de/zero-2-0. Only NRW data (GeoInfoDok 7.1) was tested; Archicad and AutoCAD were not tested.
Limits
- Upload: one unzipped .xml file up to 50 MB. ZIP archives are not accepted.
- No labels: the converter writes no texts, so parcel numbers, house numbers and street names are missing. ALKIS keeps them as attributes or as presentation objects such as AP_PTO; in the test the AP_PTO object became a point without its text.
- No attributes: DXF stores only the geometry and the layer name. For the attributes use ALKIS NAS to GeoPackage.
- The drawing keeps the original coordinates in metres (in the Herne test data E 370 836 to 379 041, N 5 709 546 to 5 714 019); the converter does not shift them to a local origin.
- All layers have colour 7 and the line type Continuous; ALKIS symbols and line styles (signature catalogue) are not written.
- Each GDAL step may run for up to 240 seconds; a longer run is stopped with an error message.
- Need files over 50 MB? Email us your file size and format.
Frequently Asked Questions
Which CAD programs can open the file?
The file is a DXF in the AutoCAD 2004 format (AC1018). We opened the test files in QCAD 3.33.1 without errors. Archicad and AutoCAD were not tested.
Why are there no parcel numbers?
In ALKIS the parcel number is an attribute of the parcel (in the test data for example zaehler 133). The converter writes only geometry and layer name, so the number is not in the DXF; labels would have to be added in the CAD program.
In which units and coordinates is the drawing?
In metres, in the coordinate system of the NAS file (in the NRW test data EPSG:25832, ETRS89/UTM zone 32N). The DXF header declares metres; the coordinates themselves are unchanged.
What happens to my file?
Your browser uploads it directly to the GDAL worker on Fly.io (region Frankfurt). The worker converts it in a temporary folder and deletes the folder after sending the result, or immediately if the conversion fails. Files are not stored permanently.