Friday, February 7, 2014

Surface styles

Support for IfcSurfaceStyles, when importing geometry from IFC files, is a feature that has been requested much over the years. Starting with IfcOpenShell 0.4 surface styles are supported. Some refer to these styles as materials, but within the realms of IFC, surface styles and materials are actually two different beasts. Materials (IfcMaterialDefinition) describe metadata that pertain to the physically built structure. For example: the composite structure of an insulated brick wall can be described using an IfcMaterialLayerSet.

Surface styles on the other hand govern the way that surfaces or solids are visualised in IFC viewers. Often there is some correlation between the two: that the style of a surface is actually an indication of the material, but this is not necessarily the case. For example in MEP models, surface styles can also be used to colour code the contents or direction of flow segments, as can be seen above. In this post you find two images attached that derive their colouring straight from the IFC file: the Hitos HVAC model and an interior part of the Cobie Duplex Architectural model. In the image below you can also see how multiple distinct styles can be applied to different items within the same product.

Subsequent releases of IfcOpenShell will also account for surface styles linked to IfcMaterials and will provide an option to slice the geometric representation of elements according to their compound layer structure defined in the IfcMaterialLayerSet.

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