ifcpatch.recipes.FixRevitTINs

Module Contents

class ifcpatch.recipes.FixRevitTINs.Patcher(src, file, logger, is_solid=True)

Fix missing or spot-coordinate bugged TINs loading in Revit

TINs exported from 12D or Civil 3D may contain dense or highly obtuse triangles. Although these will load in Revit, you will not be able to use Revit’s Spot Coordinate or Spot Elevation tool.

See bug: https://github.com/Autodesk/revit-ifc/issues/511

If is_solid is enabled, we assume the surface is represented as a solid (e.g. I have come across surfaces which are extruded by 1mm from Civil 3D). The solution will delete any faces with a Z normal less than 0.5. In case the mesh has any side faces or thickness, this should leave only the top surface which is relevant for spot coordinates and elevations.

If is_solid is disabled, then we assume the surface has no thickness. In this scenario, all faces with any normals pointing in a negative global Z direction will be flipped. This is because Revit cannot annotate backfaces.

Vertices closer than 10mm will also be merged to prevent dense portions of the TIN at a minor sacrifice of surveying accuracy. It will also triangulate all meshes to prevent non-coplanar surfaces, and delete any obtuse triangles where one of their XY angles is less than 0.3 degrees. Therefore the result will contain some minor “holes” in the TIN, but these holes will only be in dense triangles that Revit can’t handle anyway and won’t affect most coordination tasks.

Note that you may may want to run other tools like OffsetObjectPlacements or ResetAbsoluteCoordinates to fix large coordinates as these can also cause issues in Revit (such as inaccuracy or inability to use the Spot Coordinate / Elevation tool).

This patch is designed to work on any TIN-like export, typically coming from civil software. It also requires you to run it using Blender, as the geometric modification uses the Blender geometry engine.

Example:

ifcpatch.execute({"input": "input.ifc", "file": model, "recipe": "FixRevitTINs", "arguments": []})

patch()