Scaled site plans — a true-to-scale DXF plus a printable A4–A0 PDF — from a small JSON file of plain measurements in metres, or straight from the official Austrian cadastre (BEV) given a Katastralgemeinde and plot number.
No CAD application, no licence, no API key. Pure Python, runs headless — built to
be driven by scripts and AI agents (see AGENT.md).
Fictional example: 40 × 60 m plot "Grst. 100/1, KG Musterdorf", 20 × 12 m house with 5 m setbacks, 6 m access road, parking — auto-scaled to 1:500 on A3.
- Plan from measurements — parcels, buildings (hatched, area computed), streets from a centreline + width, parking with stalls, green/gravel/water areas, setback lines, free labels, dimensions (any angle).
- Automatic plot scale — picks the largest standard scale (1:50 … 1:5000) that fits the sheet, trying both orientations.
- Real sheet — frame, title block, north arrow, scale bar, all in true paper millimetres; text stays 2.5 mm on paper at any scale.
- Verified print scale —
verify.pymeasures the printed parcel in the PDF: an 80 m edge prints at 159.93 mm at 1:500 (target 160.00; the 0.05 % is PDF point quantisation of the page itself). - Audit of the finished drawing —
checkplan.pyreads the DXF back and re-measures areas, building-to-boundary and building-to-building distances. - Austrian cadastre —
kataster.pypulls the real parcel, its neighbours, building footprints and existing roads from the BEV's free vector tiles, reprojects to Gauss-Krüger metres, stitches tile seams and cross-validates each parcel against an independent land-use layer.
pip install -r requirements.txt
python build.py example/musterdorf.json -o out/ # DXF + PDF + PNG
python verify.py example/musterdorf.json # true-scale check -> PASS
python checkplan.py out/musterdorf.dxf --setback 5 # audit the finished drawing
# a real Austrian plot, from the cadastre:
python example/from_kataster.py <Katastralgemeinde> <Grundstücksnummer> [radius_m]The plan schema is documented in AGENT.md; start by
copying example/musterdorf.json.
QCAD, LibreCAD and FreeCAD are interactive editors with scripting bolted on.
ezdxf writes DXF directly from Python, has a
drawing add-on that renders to PDF, and was the only one of the four that gave a
verifiable print scale without a commercial licence. Modelspace is metres
(1 unit = 1 m, nothing pre-scaled); the PDF is emitted with
Settings(fit_page=False, scale=1000/N) for 1:N.
- Every real error was invisible from inside the generator. A setback that
read "2 m" in the code pinched to 1,15 m against a skewed boundary; a building
sat exactly on a plot line; a second sheet went silently stale. Hence
checkplan.py: audit the drawing you hand over, not the variables you held. - Cadastre tiles exist at zoom 16 only for survey geometry (~6 mm quantisation); z15 is generalised, z17 is 404.
- Tile truncation: a parcel longer than the fetch radius is cut at the tile
edge and its area comes out too small — yet it still cross-validates at
0.0000 %, because both layers are cut at the same edge. Always pass
cover_bbox; completeness is a separate test from consistency. - ezdxf traps: ACI colour 7 renders white-on-white unless both the render
context background and
BackgroundPolicy.WHITEare set; dimension text comes out ×100 withoutdimlfac = 1;get_pixmap_bytes()ignores the scale settings (write the PDF, then rasterise); hatches render as nothing without an explicitdefinition=; AR-CONC needs a paper scale of ~0.03 or it silently draws nothing.
More in AGENT.md.
This produces a drawing, not a survey: no surveyor's certification, not a
Vermessungsurkunde. Cadastral boundaries are legally binding only where the
parcel is in the Grenzkataster (rstatus == "G"). Sheet labels follow Austrian /
German drafting conventions.
Cadastral data retrieved by kataster.py comes from the Austrian Federal Office of
Metrology and Surveying (BEV) under CC BY 4.0. Any plan built from it must carry:
"Datenquelle: BEV — data.bev.gv.at (CC BY 4.0)". No cadastral data is shipped in
this repository; the example is fictional.
MIT — see LICENSE.