Hi all, this thread has deviated lots from the initial question about high water marks but on a broader level, it’s important to note that statewide maps like the NSW Base Map are not the basis for legal questions. Individual property title plans are. The statewide maps just give a good (sometimes excellent) representation of relative patterns across broad areas. To quote from the NSW Six Maps FAQ:
“It is important to note that cadastral data displayed within SIX Maps has no legal status and is intended for viewing purposes only. Only the registered deposited or strata plan of survey is recognised as the legal definition of the boundaries.” The NSW Base Map we use in OSM is the same as that shown at the Six Maps website. The reliance on property titles is shown in the two examples Cleary provided which refer to lot numbers. The property plans for the individual lots provide the legal basis for the boundaries of those lots. (Some of these might refer to natural features perhaps.). The schematic maps are indicative only. The NSW Base Map is compiled from layers, each of differing precision/accuracy. Roads, POIs, houses, etc are often very accurate. Streams are extremely coarse. Property boundaries are usually accurate in towns but often very imprecise in regional areas (inc National park boundaries etc). The “shape” of each allotment is broadly accurate, but there are a lot of offsets and imprecision in where the boundary actually is. As described in the six maps FAQ page, many of these boundaries were transcribed from old, broad-scale, paper plans. The process of increasing the accuracy of the statewide datasets is on an as-needs basis. Broadly, the bulk of attention is on newly subdivided lots in towns and cities, and remote properties, inc public lands, get little attention (unless there’s some legal appeal presumably). You can easily see these inaccuracies on the nsw base map by seeing how often road alignments deviate out of the road easements. The actual roads are geospatially accurate. On imagery and on the ground, the roads lie within fenced easements. On the base map, the easements are often offset, so roads appear to go through private paddocks. For public lands, the same issue arises. The statewide maps are the best we have usually, but they’re not the legal representation of boundaries. The Base Map is a fantastic resource, but actual boundaries often need to be moved to better align with fence lines. Where the boundaries follow creeks and the like, the boundaries are probably best treated as indicative and left untouched, as there’s no verifiable way of knowing where they should lie without chasing up individual property plans. Cheers Ian _______________________________________________ Talk-au mailing list [email protected] https://lists.openstreetmap.org/listinfo/talk-au
