> What are you envisioning when you say geo-diff? I'm interested in geodiff > tool too, but haven't been able to get anyone to come up with good ways of > visualizing the difference data.
I did a SQL-based diff of TIGER 2008 -> TIGER 2009. This only looked for changes in named ways; adds and deletes. Given separate OSM data sets of 1.) New ways - load into JOSM as a separate layer. New ways that I accept and validate can just be copied to the OSM data layer and stitched in. 2.) Deleted ways - load into JOSM as a separate layer. I can validate and delete the ways from the OSM data layer. 3.) The final dimension to define a full geo-diff is finding ways that have had nodes added, moved, or deleted. Once again, load into JOSM, validate and apply to the OSM data. It would be necessary to ensure that existing edits are preserved - in most cases existing edits would be preferred and may already contain the same fix as the updated TIGER. A geo-diff is less useful in cases where an entire county has been refreshed from the county GIS data from more accurate data because it would basically return the entire TIGER 2010 dataset.
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