[postgis-users] Trace network from each source node and check that the trace reaches the sea

[Shaozhong SHI]

Hi, Steve,

The network-walking-in_PostGIS sometimes produces additional straight lines.

Why does that happen?  How to make sure that resultant lines are correct?

Regards,

David

On Thu, 30 Dec 2021 at 23:36, Stephen V. Mather <svm at clevelandmetroparks.com>
wrote:

> Hi David,
>
> This is a good example. I have modified this to walk networks before, and
> it's a minimal and understandable example:
>
> http://blog.cleverelephant.ca/2010/07/network-walking-in-postgis.html
>
> There may be some better ways to do this, as the postgres tooling has
> changed quite a bit. The use of a function may be precluded by some modern
> fancy join type. Others can speak better to that than I can these days.
>
> Also, if you don't mind installing one more thing, pgrouting will do
> network traversal much more efficiently than a *WITH RECURSIVE* network
> traversal:
>
> https://pgrouting.org/
>
>
> Cheers,
>
> Best,
>
> Steve
>
>
> On 12/30/21 4:13 PM, Shaozhong SHI wrote:
>
> *WARNING: This email originated outside of Cleveland Metroparks. DO NOT
> CLICK links or attachments unless you recognize the sender and know the
> content is safe.*
> In hydrological network, how to trace network from each source node and
> check whether the trace can reach the sea?
>
> Any examples?
>
> Regards,
>
> David
>
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