I work with a small non-profit mountain bike trail advocacy organizationand as a result have created a number of PDF-based maps. These are all Mercator projection, built off of OpenStreetMap data, and work great as print maps. For example: Map 1, Map 2
I'd like to georeference these so they can be viewed with something like Avenza PDF Maps on trail users' phones. Unfortunately, something like Avenza MAPublisher is beyond what we can afford.
How can I georeference my existing maps using free/open source/lower cost tools?
Best Answer
Regarding the original posted question - I don't think this is possible without somehow rasterizing the original PDF. In regards to the bounty, I am posting the following as an answer.
Go to http://www.frontenacmaps.ca/Html5Viewer/index.html?viewer=Public, zoom to your area of interest, add bike trails/roads etc., click on the wrenches icon in the upper-right corner of the map, on the 'Printing and Exporting tab, export the map as a GeoTIFF (GeoTIFF has location information stored in the file).
Open the exported geotiff file in QGIS 3.2 and warp/reproject it to WGS84 coordinates.
Remove the original Export.tif file. Right-click in Layers menu -> Remove Layer.
Make sure the Coordinate System is set to WGS84. Click on the coordinate system icon in the lower-right corner of QGIS, set it to WGS84.
Add a new Layout.
Set the page size.
Add a new map canvas, size it to the page, double-check coordinate system is correct, print it as a Geospatial PDF.
ADJUSTING MAP CONTENTS NOTE: Pan and zoom around in the map window with the tool pictured below. Activate tool, click in map canvas, wheel-mouse to zoom in/out, press/hold mouse button and drag mouse to pan etc. Print to PDF.
Open in Acrobat. Look for the 'Measure' Tools. Click on 'Geospatial Location Tool' -> click in the map -> you should see values in the coordinate display and be able to take distance measurements etc.