★ Grid Infrastructure

Substation drawings, profile plans, as-builts — on the map

Bring the engineering department's DWG / DXF / DGN drawings onto the map alongside your transmission and distribution network: substation one-line diagrams, structure profile drawings, corridor as-builts, and equipment layouts — georeferenced with control points or a source CRS, then served as GeoJSON, MBTiles vector tiles, or GeoPackage. No more toggling between AutoCAD/MicroStation and the GIS just to see a drawing in context.

DWGDXFDGN Substation one-linesProfile drawingsAs-builts affine · polynomial-2MBTiles-vector

What it reads

Three CAD formats, three outputs

DXF is read in-process via the managed OGR driver (always available). DWG and DGN fall back to external ogr2ogr with the OpenDesign / ODA driver — the response carries a driver field so the UI can tell you when a portable GDAL is needed.

Outputs served as layers: GeoJSON (GeoJSONLayer), MBTiles vector tiles (VectorTileLayer), and GPKG (FeatureLayer).
All output geometry normalized to EPSG:4326 (WGS84); the MBTiles path additionally reprojects 4326 → 3857 during tiling.
Files written in-process for DXF/GPKG — no external GDAL required for the common case.

POST /api/cad/convert (multipart)

// DWG/DXF/DGN → georeferenced layer
fields:
  file        = site-plan.dwg
  format      = mbtiles-vector
  georefMode  = controlPoints
  controlPoints = [
    {src:[0,0],   wgs84:[-74.00,40.71]},
    {src:[500,0], wgs84:[-73.99,40.71]},
    {src:[0,500], wgs84:[-74.00,40.72]}
  ]
  transformKind = affine   // or polynomial-2

→ driver:"ogr2OgrFallback"
→ served at /api/tiles/{id}/…

Two ways to georeference

From local CAD coords to real-world positions

CAD lives in arbitrary drawing units. VoltGrid gives you two robust paths onto the globe, both with a live RMSE preview before you commit.

🎯

Control points

Click ≥3 matching points between the drawing and the map. A least-squares affine (6-param) or polynomial-2 (12-param) transform is solved with RMSE reported — so you see the fit before importing.

🌐

Source EPSG

If the plan already carries a real projected CRS (e.g. a UTM zone), supply it directly. OSR reprojects to WGS84 with no manual clicking.

The conversion API

Convert, preview, serve

Capability	Endpoint	Notes
Preview	POST /api/cad/preview	Bounds, layers & GeoJSON in source coords
Convert	POST /api/cad/convert	Multipart → GeoJSON / MBTiles-vector / GPKG
Features	GET /api/cad/{id}/features.json	Transformed GeoJSON, ETag / 304 cached
Tiles	GET /api/tiles/{id}/{z}/{x}/{y}	MBTiles-vector rendering
Style	GET /api/tiles/{id}/style.json	Vector tile style
Spatial facades	/api/spatial/cad_{id}/…	MVT / OGC Features / FeatureServer
Remove	DELETE /api/cad/{id}	Removes from registry + deletes files

Source: CAD_IMPORT.md and Src/LocalMapServer/Cad/ (CadReader, CadGeoreferencer, CadConverter, CadRoutes). Affine/polynomial math via least-squares; reprojection via GDAL/OSR.