Based on this I'm comfortable that we can use this data under the existing waiver we have.
Thanks Andrew
What I'd suggest is to document your process for deriving the stream geometry from the ELVIS data and what you're proposing to import and how. eg. how do you determine how far upstream to map, how do you determine if what's in OSM is better already than ELVIS or if ELVIS is better.
The general process of deriving stream data from DEMs is documented at https://maps.ozultimate.com/wiki/qgis_hydrology In terms of detail, I have found that using the SAGA Channel Network tool, an Initiation Threshold of around 9.6-9.7 (based on D8 flow, log accumulation), along with a minimum length of around 60m, gives a similar level of detail to the existing DCS stream data. That's in my areas of interest, typically the Blue Mountains. A different threshold might apply in flatter country. At this stage I'm not proposing an import. I think there are too many potential problems around connectivity. I did the "import" (manually!) of the missing named streams for the Sydney Basin, and it involved a massive amount of work manually connecting things up, fixing broken connections etc. I have no idea how you would do an automated import of streams without a lot of manual work, though I'm happy to take suggestions/advice! I was mainly proposing to improve the existing streams with the aid of an additional source of data. cheers Tom ---- Canyoning? try http://ozultimate.com/canyoning Bushwalking? try http://bushwalkingnsw.com _______________________________________________ Talk-au mailing list [email protected] https://lists.openstreetmap.org/listinfo/talk-au
