How to successfully convert a Revit BIM model into a lightweight augmented reality experience for a construction site?

Export the Revit model as FBX or IFC, then decimate the mesh in Blender or Autodesk 3ds Max to mobile-friendly polygon counts (under 200K polygons). Divide the model into location-based sections, partitioned by floor or zone, that load independently based on the user's GPS or AR-tracked position on site: as the worker moves into a new section, the relevant 3D chunk streams in while distant sections unload from memory, keeping the app within typical mobile memory limits of 1 to 2GB usable. Use physical marker placement throughout the building so the AR app can use image recognition to accurately overlay the BIM plans onto the physical construction in real-time.