You might be able to skip the manual tracing process that Devdatta
linked to and pull out vectors directly, if your PDFs are made that way.
1. Extracting from PDF
- It's one of those PDFs exported from Autocad or so where you can see multi-layers and turn them on or off.
- Rajesvari used a command-line GIS tool called "ogr2ogr" to extract individual layers from the PDF into .geojson shapefiles.
- There was a tricky bit where the output lat-longs were all like (716882.20,3166456.28) - a different CRS and we didn't know which.
- I used
http://projfinder.com/ to find it, then Rajesvari included CRS conversion into the ogr2ogr commands to produce proper shapefiles.
- You can see all that in this repo:
https://github.com/draftmpd41/layers_draft_delhi_master_plan_2041 - see the .bat file for the ogr2ogr commands