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Some years ago QGIS was useful to me in spite of its UI: I got a PDF map of certain infrastructure that was not georeferenced, and I was able to correct its pro
by AlbertoGP 4y ago
Some years ago QGIS was useful to me in spite of its UI: I got a PDF map of certain infrastructure that was not georeferenced, and I was able to correct its projection to Web Mercator with great acccuracy. But at the end I was somehow unable to find out how to export the data! QGIS did show me with the transformation matrix it had built and I wrote a program that applied that matrix to my files.
- anakaine 4y agoIn the vast majority of cases you cannot turn a PDF into spatial data, except for georeferencing it as an image. There are some exceptions, such as when the PDF already includes georeferenced vector data, but its very unlikely you had that sort of file given the issue you described. You likely either: - needed to export an image of the data (raster); - needed to digitise the data within; - needed to extract the vector data first from the pdf and work out how to deal with it. Opening a pdf without appropriate data structures into a gis software package is akin to taking a picture of a billboard that has a printed image of a map on it and then expecting to be able to do anything with that picture. The pdf is a bit better, but not by much unless it began life as a georeferenced pdf with vector data maintained.
- AlbertoGP 4y agoThe PDF was a map of infrastructure that was likely produced with ArcGIS. By the time I got it, it was just a vector image. The infrastructure in question was pipelines, represented in the PDF by lines, so georeferencing them was enough to get spatial data adequate for the application.