[talk-au] Use of DEM data to generate streams

[Andrew Harvey]

On Tue, 14 Jan 2025 at 22:24, Tom Brennan <website at ozultimate.com> wrote:

> One field that I have in my data that doesn't have an equivalent in OSM is
> a relevance/importance field. Essentially a number that gets bigger the
> larger the stream. NSW SS data also has a relevance field from 1?-9 (where
> 9 is the smallest). The main problem with streams in OSM at the moment is
> that they all suddenly appear at the same zoom level, even though in some
> cases the streams are larger than the nearby rivers that they flow into! It
> makes the map suddenly very cluttered. Yes, this is a rendering issue, but
> there's not much for the renderer to go on.
>
> There are the width and intermittent tags, but they don't really give you
> a relative importance.
>

I think that's something the downstream data consumers can calculate from
the OSM data rather than tags we add to OSM. This is how
https://waterwaymap.org/#map=9.87/-33.6952/150.5121 does their stream
thickness rendering.


> > Either way I think it would be helpful for others to have the end-to-end
> > process documented on the wiki.
>
> If I develop it further, then I'll add some more documentation. At the
> moment, I am just exporting the layer as GeoJSON and dragging it into ID.
> There are videos and tutorials on various things you can do with the DEM
> data at:
> https://maps.ozultimate.com/wiki/nsw_lidar


Nice documentation there.
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