ogr2ifc

ogr2ifc converts GIS data to BIM models using GDAL/OGR (read) and IfcOpenShell-python (write).

This allows the import or visualisation of GIS data in a BIM project.

All GIS vector data formats supported by GDAL/OGR can be converted.

GIS features are converted to IfcProduct/IfcWall elements. GIS attributes are also added to the IFC element as custom property sets.

GIS geometries can be converted to multiple IfcShapeRepresentations.

Coordinates can be transformed to match the BIM project coordinate system using simple transformation and rotation, or a custom coordinate transformation can be applied by passing a transformation function.

Depending on the source and destination representation geometry types, GIS geometries are extruded vertically to produce lines, surfaces or volumes. Extrusion boundaries can be defined using fixed elevations, or using attribute values from each GIS feature (eg: 'floor-slab_elevation' and 'roof_apex') data attributes.

Development Status

This tool is currently in development, but is useable in it's current state.

Implemented

• Polygon implemented (swept solid extrusion)
  • Inner holes supported
  • Multipolygons supported
• Attributes added as custom property set
• Coordinate transformation from GIS to BIM coordinate system

Under Development

• Points, lines, footprints
• Curved geometry
• Surfaces
• Create features as part of IfcSpace instead of IfcBuilding
• use of IFC4 HasCoordinateOperation/IfcMapConversion as alternative to transformation

Installation

Dependencies:

• Python 3
  • ifcopenshell-python
  • GDAL
  • shapely

Copy file ogr2ifc.py to the script folder or to a folder on the python module search path.

Command Line Use

Type python ogr2ifc.py -h for help with the command line use.

Example use in command line:

python ogr2ifc.py gis2bim.ifc polygons.shp -top 520 -bottom 450

Python Module Use

The python classes offer more flexibility and functionality, including coordinate transformations. See the main conversion class Ogr2Ifc for details.

Example use in python scripts:

o2i = Ogr2Ifc('gis_files/complex.gpkg', bottom_elevation='bottom', top_elevation='top')
o2i.add_vector_layers('multipolies')
o2i.save_ifc('test.ifc')

Geometry Representations

Multiple IfcShapeRepresentations can be created for each feature, as shown in the table below.

Ogr2Ifc Attribute (IFC shape representation identifier)	Description	Implemented for OGRGeometry Class
		Point	Line	Polygon	Triangle/Polyhedral/TIN
CoG	Center of gravity 3D IfcCartesianPoint	(Y)	(Y)	(Y)
Box	Bounding box			(Y*)
Axis	Line representation of an element	(Y*)
FootPrint	Foot print projected to ground view			(Y)
Surface	3D Surface representation		(Y*)		(Y)
Body	3D Body representation			Y*
* Extruded to elevation bounds (Y) planned functionality

If an IfcShapeRepresentation is not desired, this can be prevented by setting the relevant Ogr2Ifc attribute to False prior to conversion.

For example:

o2i = Ogr2Ifc('gis_files/complex.gpkg')
o2i.Box = False
...

Transformation

To convert coordinates from a GIS WorldCoordinateSystem to the IFC project coordinate system, a function can be created and passed to the converter as follows:

from ogr2ifc import Ogr2Ifc, transformer

# Create coordinate transformation function
coord_tran = transformer(eastings=2719310, northings=1225070, 
                         orthogonal_height=410.10, rotation=44.2939)

# Convert
o2i = Ogr2Ifc('gis_files/poly.shp', coord_transformer=coord_tran)

Custom transformations can also be provided, for example any shapely transformation, including map reprojections.

Example Visualisation

GIS File

BIM IFC File