Converting CAD Datasets to IMDF: Part 2

Liz Sanderson
Liz Sanderson
  • Updated

FME Version

  • FME 2018.x


This article is Part 2 of 3 of the AutoCAD to Indoor Mapping Data Format (IMDF) tutorial series. This part moves away from FME Desktop and into AutoCAD to manually clean up the drawings before writing to IMDF. Review each of the issues against your drawing and then fix them by following the examples. This part also creates a Location.dwg file that is used for georeferencing in Part 3.

Please note that this article is for demonstration purposes only in Windows. The data is not supplied. If you require data please see the Scenario: Victoria Airport Esri Geodatabase to IMDF article

Disclaimer: This is not an AutoCAD tutorial, this article is only meant to highlight the issues that may need to be fixed, not how to fix them.



Windows Operating System

Converting CAD Datasets to IMDF: Part 1 completed


Google Earth (optional)


Before You Begin

Ensure that Part 1 was completed and you have an AutoCAD file that is aligned with attributes following the IMDF naming convention.


Completed DWG from Part 1 viewed in AutoCAD


Workflow Overview

Part 2a: AutoCAD Clean Up

The ToEdit.dwg created in Part 1 should be opened in AutoCAD and then each of the layers reviewed with the following list of potential issues that will need to be manually fixed:


A. Single Lines and Openings

Where single line processing and opening extraction are not perfect the results may need touching up in AutoCAD, especially small ‘notches.’


Problem A: Notch artifacts from single line process



Fix A: Notches removed


B. High Rooms that Open to Below

High rooms that extend into the level(s) above need to be reproduced on that level, on the layer ‘OpenToBelow.’


C. Openings on Unit Boundaries

Openings should sit on Unit boundaries. At Openings between Units, both Unit boundaries should be coincident at these Openings. The AWA layer can be used to check for these Openings.


Problem C: Opening not on Unit boundary and column prevented the wall from being single-lined



Fix C: Opening rotated into line and Unit boundary adjusted


D. Exterior Openings

Exterior Openings should sit on Unit and Level boundaries. Unit and Level should be coincident at these Openings.


Problem D: Unit (cyan) should be coincident with Level (red) at Openings (blue)



Fix D: Unit boundary moved


E. Adjoining Units without a Door Symbol

Adjoining Units that are open to each other, but do not have a door will need to have the Opening between them placed manually.


Problem E: Units have no Openings due to the natural absence of door symbols



Fix E: Use AWA layer (white) as a guide to place new Opening lines (red)


F. Null Areas

Any null areas in the Units layer, inside the Level boundary, will be considered as a wall in the final IMDF. If any are known to be structural columns, they should be moved to the Columns layer for that level.


G. Small Details

Small details (less than 2 ft.) should be removed from the Levels boundaries, and small offsets between the Level boundaries should be removed.


Part 2b: Georeference Drawing

Once the geometry has been cleaned up, the final step in AutoCAD is to determine a precise latitude/longitude coordinates for a reference point on the building.

If a reference point is not available, Google Earth can be used. A reference point can be located by adding a placemark. In the New Placemark dialog, make note of the latitude/longitude values. From there, use the Ruler Tool to determine the heading of a vertical edge in the DWG file.

Back in AutoCAD, create a new empty file called Located.dwg and add the edited DWG as an Xref. The Xref is set so that the reference point is at 0,0 in the edited DWG file. Finally, the Xref is rotated so that it matches the alignment that was in Google Earth.

The georeferenced DWG is then saved and moved back into FME for the final processing. Continue to Part 3 to learn how to finish the processing.


Edited DWG Xrefed to rotate and align by a known point

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