Frequently Asked Questions

How do I georeference a floor plan using AutoCAD?

AutoCAD DWG files are commonly in a local coordinate system whose origin is close to their data. SISfm can use these for most purposes, but for some purposes (such as way finding) all floor plans and site plans must be in the same coordinate system, and for display with aerial imagery such as Google Maps they must be georeferenced.

Plans can either be georeferenced in their original format (e.g. by using AutoCAD), or they can be georeferenced by transforming their coordinates in a Cadcorp SWD file, leaving the dataset files unchanged. If DWG files are currently being compiled directly, to do the latter compile them with DwgSaveSwd set TRUE, then add the georeferencing transforms to the SWD files, and subsequently compile those instead.

A separate FAQ topic describes how to georeference a floor plan using Cadcorp SIS. Here we show how to georeference a floor plan using the the Autodesk AutoCAD application, using the AutoLISP file GEOREFSIS.lsp (available from IFM on request).

To load GEOREFSIS.lsp in AutoCAD, enter APPLOAD into the Command Line box, press Enter, browse to GEOREFSIS.lsp and load it. (N.B. This step can be automated, see Autocad help for "load on startup").

This method requires a site plan DWG file which is georeferenced and has a layer containing building outlines.

This site plan DWG is then modified to XREF all building floors (moved and rotated) to be above each building outline (care and precision in this step will yield best results). A coordinates file is then exported using the EXPT function of GEOREFSIS.lsp.

After that, to georeference a floor plan, its DWG file is opened and the GEOREFSIS.lsp function CVSIS is used to read the coordinates file and create a georeferenced copy of that DWG file.

Part 1 - Creating the coordinate reference TXT file (one-time)

  1. Open the site plan (master) DWG in AutoCAD.
  2. From the ribbon select INSERT, from the Reference section select Attach, and use the Reference File dialogue to select a floor plan (source).
  3. With the floor plan now open, click and drag it into position over its building outline on the site plan. Use your preferred methods to align and rotate the plan to the best position.
  4. Repeat steps 2 and 3 until all floors are positioned over their building.
  5. Repeat steps 2 to 4 for all buildings.
  6. Enter EXPT into the Command Line box and press Enter to run the Export Coordinates command. This creates a coordinate reference TXT file (master) with the same name as the site plan, e.g. site.txt. In this file there will be a line for each XREF'd building floor plan with x, y, scale and angle values based on the coordinate system of site.dwg.
  7. Close and Save the site plan DWG.

Part 1 only needs to be repeated if changes are made to the site, e.g. new construction.

Part 2 - Creating georeferenced DWG floor plans (initially or when revised)

  1. Open a floor plan DWG (source) to be georeferenced, or one that has been modified and therefore needs to be reprocessed.
  2. Enter CVSIS into the Command Line box and press Enter. The LISP derives the site from the DWG's path and determines the correct site coordinate reference TXT file to use (e.g. for ...\source\site_code\floor.dwg it uses ...\master\site_code\site.txt). It reads this file to locate the floor's coordinate record and uses those values to create a georeferenced copy of the floor plan DWG in the configured (target) folder (e.g. ...\target\site_code\Buildings\georeferenced-copy.dwg. N.B. During this step the floor plan will move out of view and reappear in its correct orientation.
  3. Close the floor plan DWG (without saving).
  4. If further plans are to be processed repeat steps 2 to 4.

The georeferenced copies are placed in the sisdata\site_code\Buildings folder ready for use in SISfm swd's

Folder structure used by GEOREFSIS.lsp: 



LISP SettingFolderFile


(master)...\Mstrdata\site_codesite.dwg


(master)...\Mstrdata\site_codesite.txt


(source)...\dwgdata\site_codebuilding\original-floorplan.dwg


(target)...\sisdata\site_codeBuildings\georeferenced-copy.dwg

If you need further assistance, please contact IFM Support <support@integratedfm.com.au>.