How do I create a geospatial PDF?

Many proprietary terminal procedures are distributed as a PDF file. Standard PDF files without embedded geospatial information cannot show your GPS position on them or be overlayed on the Maps view in ForeFlight. Geospatial PDFs are supported by ForeFlight's as georeferenced charts.

ForeFlight supports both the Adobe and OGC standards for geospatial PDF files. You can georeference PDF files and export them as geospatial PDFs using several different GIS software options, including Avenza MAPublisherTerraGo Composer, and QGIS.

To georeference your plates, you'll first need to download and install the program you plan to use. This article will cover georeferencing a terminal procedure using the free, open-source program called QGIS

Once you have the program installed, to add geospatial information to your plate, you'll need the Georeferencer GDAL plugin. To add the Georeferencer GDAL plugin, select PLUGINS > MANAGE AND INSTALL PLUGINS. Search for GEOREFERENCER GDAL. Once you see it in the list, make sure it is installed and that the box is checked to the left of its name. 

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Image 1. Install the Georeferencer GDAL plugin and check the box next to it.

Once the plugin is installed, begin a new project and select RASTER > GEOREFERENCER.  

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Image 2. Open a new project and select RASTER > GEOREFERENCER. 

Once the Georeferencer opens, click on the OPEN RASTER button to choose your terminal procedure. 

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Image 3. Select OPEN RASTER and choose your file.

NOTES: Your PDF terminal procedure will need to be converted to an image (PNG, JPEG, etc.) before it can be imported into QGIS Georeferencer. Also, when converting your PDF to an image file, it is recommended you crop your terminal procedure to eliminate unnecessary margins. 

After you select OPEN, you will may a Coordinator Reference System Selector popover. Make sure WGS 84 EPSG:4326 is selected and then choose OK.

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Image 4. Select WGS 84 EPSG:4326 and then select OK.

After your plate has opened in the Georeferencer, you may see a window to add Lat/Long values. Click CANCEL. Use the ADD POINT button to define at least three easily identifiable points on your plate using Lat/Long values. If you don't see the Lat/Long entry window, it may be behind your Georeferencer window. The more precise you are, and the more points you specify, the more accurate your plate georeferencing will be.

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Image 5. Define a minimum of 3 Lat/Long points on the plate.

We recommend defining the waypoints that make up your approach. The coordinates of these waypoints are generally made available by the originator of the procedure. Alternatively, you can find waypoint coordinates in ForeFlight or the FAA database.  

After defining a minimum of 3 points, click the TRANSFORMATION SETTINGS button and verify the following settings:

-Transformation Type is set to LINEAR.

-Resampling Method is set to NEAREST NEIGHBOUR.

-Target SRS is set to EPSG 4326: WGS 84.

-Check the box for "Load in QGIS when done."

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Image 6. Transformation Type is set to LINEAR. Resampling Method is set to NEAREST NEIGHBOUR. Target SRS is set to EPSG 4326: WGS 84. Check the box for "Load in QGIS when done."

After verifying the Transformation Settings, click on the START GEOREFERENCING button.

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Image 7. Select START GEOREFERENCING.

Once georeferencing is complete, the plate will be copied from the Georeferencer to the QGIS home page. From the home page, select RASTER > CONVERSION > TRANSLATE (CONVERT FORMAT). 

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Image 8. Select RASTER > CONVERSION > TRANSLATE (CONVERT FORMAT).  

Selecting Convert Format will open a new window. Select the Converted "..." button and choose SAVE TO FILE. Specify the destination and verify PDF FILES (*.PDF) is selected as the exported file type. Select SAVE. Select RUN in the Translate (Convert Format) window. Your plate will be exported as a geospatial PDF that can be used in ForeFlight. 

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Image 9. SAVE TO FILE > Choose Destination > Specify PDF FILES (*.PDF) as export format.