Pretty cool that these maps are finally free and easy to get. It's been really interesting to see LPI slowly come around on this issue. They used to be super-protective of their data! Open data FTW. (Taxpayer-funded, after all.) The next step is to get all the NSW DTDB (Digital Topographic Database) available free for download as shapefiles. (
data.nsw.gov.au is pretty much empty of topographic datasets, currently.)
I'd also love to see them step up their game and replace the old coarse vegetation underlay with the new SPOT5 data (
SPOT5 woody extent and foliage projective cover from 2011: much more detailed at about 5-10 metre resolution, versus 25 metres previously). My nswtopo maps use this data as do all our ACT rogaine maps. It looks so much better. And how about a nice shaded relief on the top? I love love love a good shaded relief depiction, it makes a map much more intuitive and attractive. I implemented
this multi-directional shaded relief algorithm for my Victorian maps with great results.
As for converting GeoPDFs like these ones to GeoTIFFS, just get the GDAL tools installed on your machine and stop fearing command-line! :) It's as easy as:
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gdal_translate '8727-3S TUGGERANONG.pdf' '8727-3S TUGGERANONG.tif'
If you're using Avenza Maps, just get a copy of Tom's spreadsheet on your device and then open or share the link for the map you want. (Alternatively, download from the etopo link.) It should give you an option to open with Avenza Maps, and the map should download and install from within the app. You can change the import DPI in settings if you want higher resolution than the default.
Yes, it kinda sucks what Avenza have done with their app from 2.0 forward. (Artificial limit of three self-imported maps at any one time.) Their subscription model to remove the restriction is ludicrous. They have trashed their app-store rating with the backlash. I really hope they relent before their casual users just move on. It's really nice to be able to import GeoPDFs and GeoTIFFS directly on a mobile app; I don't know of any other apps that can do that. Hint: on Android you can just download and install the last pre-2.0 version to keep unlimited map imports. Just don't update the app once installed. The APK is
Avenza_PDF_Maps_1.7.3.apk. There are sites where you can download older versions of APKs, assuming you trust them.
Michael & Phil, for mosaicing the maps, there is neatline data embedded in the files. (The neatline is basically the border of the map itself within the larger page.) You can see it with
gdalinfo:
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gdalinfo 8727-3S\ TUGGERANONG.pdf
# => ... NEATLINE=POLYGON ((680019.768017437 6068807.67187656,679959.751862371 6083912.02000497,705775.764175994 6083901.85531787,705792.904086281 6068817.74320769,680019.768017437 6068807.67187656)) ...
It's possible to use this information during the mosaic, so the borders don't mess things up. (There is some information
here; it's a bit messy but it does work.)
I converted a couple of the etopo PDFs to tiff and opened them in Google Earth. I couldn't find any places which were out by more than a few tens of metres. Certainly no 100m or 500m discrepancies, so I think the georeferencing is correct. (Unlikely that it wouldn't be.)