Industry Foundation Classes (IFC) Reader Parameters

• Read Property and Quantity Set Definitions – Check this option to enable reading PropertySetDefinition features. Property and quantity sets will have an ifc_element_type of PropertySet and ElementQuantity respectively. User-defined sets will have suffixed type attributes for each property or quantity in the set, including .PropertyType and .ValueType.
• Read Material Definitions – Check this option to enable reading MaterialDefinition features. MaterialDefinition features can have an ifc_element_type of Material, MaterialList, or MaterialLayerSet.

Use this parameter to expose Format Attributes in FME Workbench when you create a workspace:

• In a dynamic scenario, it means these attributes can be passed to the output dataset at runtime.
• In a non-dynamic scenario, this parameter allows you to expose additional attributes on multiple feature types. Click the browse button to view the available format attributes (which are different for each format) for the reader.

Coordinate systems may be extracted from input feature data sources, may come predefined with FME, or may be user-defined. FME allows different output and input coordinate systems, and performs the required coordinate conversions when necessary.

For systems that know their coordinate system, the Coordinate System field will display Read from Source and FME will read the coordinate system from the source dataset. For most other input sources, the field will display Unknown (which simply means that FME will use default values). In most cases, the default value is all you'll need to perform the translation.

You can always choose to override the defaults and choose a new coordinate system. Select More Coordinate Systems from the drop-down menu to open the Coordinate System Gallery.

Changing a Reprojection

To perform a reprojection, FME typically uses the CS-MAP reprojection engine, which includes definitions for thousands of coordinate systems, with a large variety of projections, datums, ellipsoids, and units. However, GIS applications have slightly different algorithms for reprojecting data between different coordinate systems. To ensure that the data FME writes matches exactly to your existing data, you can use the reprojection engine from a different application.

To change the reprojection engine, Select Workspace Parameters > Spatial > Reprojection Engine. In the example shown, you can select Esri (but the selection here depends on your installed applications):

Use this parameter to enable or disable reading all of the geometric representations found in the source file.

Use this parameter to select which geometric representations in the file should be read.

If no representations are selected, Body and Axis representations will be read by default.

Unnamed representations will be given a default name of Unnamed_<ifc_representation_type>, or Unnamed if the representation type is also empty.

IFC Documentation References

Use this parameter to select whether the IFC_API reader reads Georeferenced or Local coordinates on features.

• Georeferenced coordinates will have the transformation specified by the IfcCoordinateOperation (either IfcMapConversion or IfcRigidOperation) applied, and the associated IfcCoordinateReferenceSystem (either IfcProjectedCRS or IfcGeographicCRS) will be set as the coordinate system on the feature.
• Local coordinates will not have the IfcCoordinateOperation (either IfcMapConversion or IfcRigidOperation) applied, and the feature will not be tagged with a coordinate system.

A search envelope (also known as a bounding box) is a rectangular area that defines a geographic area. In FME, the easiest way to define a search envelope is to use search envelope parameters.

Defining a search envelope is the most efficient method of selecting an area of interest because FME will read only the data that is necessary – it does not have to read an entire dataset. Search Envelope parameters apply to both vector and raster datasets and can be particularly efficient if the source format has a spatial index.

Most FME readers have parameters to define the search envelope of data that is being read:

The parameters include the x and y coordinates of the bounding box as well as a parameter that defines the coordinate system.

How to Define the Bounding Box

Using the minimum and maximum x and y parameters, define a bounding box that will be used to filter the input features. Only features that intersect with the bounding box are returned. Note that the bounding box intersection is not a full geometry intersection (based on spatial relationships) that would be returned by a transformer like the SpatialFilter.

When selected, the IFC model will be validated against its schema version after the input file is read. Any schema violations will be output as errors in the translation log.

This setting controls how nested attribute names are separated when reading IFC data, including property sets, quantity sets, and other nested structures. By default, the delimiter is ".", so attributes appear as Pset_WallCommon.Reference. Any single character except a space can be used as the delimiter. If the dataset contains the chosen delimiter in set or property/quantity names, the reader will output a warning, and the IFC writer will not output these attributes correctly.

Note that list attributes will be delimited by "." in all cases, regardless of the selected delimiter (for example, ifc_is_defined_by{}.Name)

When checked (default), openings will be read and a void will be calculated and removed from the geometry. Solids will be turned into CSGs.

• Output Opening Geometry in Subtractions – When checked, opening geometry will be drawn. All opening geometry is transparent, and is appended as an aggregate part to a feature’s existing geometry.