<div dir="auto">In addition to my previous email (My apologies for double post)<div dir="auto"><br></div><div dir="auto">Point 2 : An alternative would be to bring a small addon to the current topology-geometry implemtentation and provide a way for the user to disable node creation when 2 lines intersects or 1 line self-intersects... This could be an answer to to most uses cases I know, but as long as l know this is not promoted by any ISO Standard.</div><div dir="auto"><br></div><div dir="auto">I do not know if such implementation would be accepted as part of a postgis topology extension. What do you think ?</div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">Le mer. 20 nov. 2024, 22:02, Pierre HARDY <<a href="mailto:pierre.hardy5@gmail.com">pierre.hardy5@gmail.com</a>> a écrit :<br></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="auto"><div dir="auto">Hello Felipe,</div><div dir="auto"><br></div><div dir="auto">I am highly interested in implementing such feature for an application in hydraulics network modelling (check EPANET) some implementations of the topology-network logic in postgis contrib packages would be nice to amswer this need.</div><div dir="auto"><br></div><div dir="auto">To answer your points:</div><div dir="auto"><br></div><div dir="auto">1. I agree, but PgRouting does not provide editing functions, this is a high limitation and make PgRouting not suitable for easy and reliable topology edition from a desktop client such as QGIS without implementing some additional logic outside.</div><div dir="auto"><br></div><div dir="auto">2. After reading the standard I agree with you, and suggest that ST_ function described by the standard must be implemented as a first step. In a second step we should plan to combine them in more "smart" functions/logic that can handle real user needs for edition from a desktop client.</div><div dir="auto"><br></div><div dir="auto">3. For a first implementation, a 2D support is sufficient to the application I knows in water supply modelling.</div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">Le mer. 20 nov. 2024, 02:24, Felipe Matas <<a href="mailto:felipematas@yahoo.com" rel="noreferrer noreferrer" target="_blank">felipematas@yahoo.com</a>> a écrit :<br></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div><div style="font-family:Helvetica Neue,Helvetica,Arial,sans-serif;font-size:16px"><div></div>
<div dir="ltr">Ufff, I also wanted this time ago, and still want it! is just there is some things to take care.</div><div dir="ltr"><br></div><div dir="ltr">1. PGRouting already has Topologies, they do not follow the SQL/MM standard, also do not have the functions for a user be able to use it</div><div dir="ltr">2. The standard is well defined, is just actually do not define anything else, functions that take advantage of a Network Topology to make them useful, would be great be able to at least list functions for that, the standard is like SF without any spatial operation.</div><div dir="ltr">3. Personally, I think in this case 2D Points are a very hard constrains, one very useful case for a Network Topology are roads, but in a lot of places int he world, to have a valid Network Topology you need 3D Points, this causes to one of the most useful uses would be impossible.</div><div dir="ltr"><br></div><div dir="ltr">From my perspective the ideal is have a Standard v2, and be implemented on PGRouting instead of Postgis.</div><div dir="ltr"><br></div><div dir="ltr">Thx!<br></div><div><br></div>
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El martes, 19 de noviembre de 2024, 11:23:04 a. m. GMT-3, Pierre HARDY <<a href="mailto:pierre.hardy5@gmail.com" rel="noreferrer noreferrer noreferrer" target="_blank">pierre.hardy5@gmail.com</a>> escribió:
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<div><div id="m_3985302157009632979m_4275956909186683588m_-800965464870258210yiv0056779421"><div dir="ltr"><div dir="ltr"><div dir="ltr"><div dir="ltr"><div dir="ltr"><div dir="ltr"><div dir="ltr"><div>Hello PostGIS devs,</div><div><br></div><div>It seems that "postgis_topology" extension does not support topology-network approach.</div><div>Here are my sources:</div><div><ol><li>What is topology-network: <a rel="nofollow noopener noreferrer noreferrer noreferrer noreferrer" href="https://www.gaia-gis.it/fossil/libspatialite/wiki?name=topo-intro" target="_blank">https://www.gaia-gis.it/fossil/libspatialite/wiki?name=topo-intro</a></li><li>Source no1 indicating that Postgis does not support topology-network approach: <a rel="nofollow noopener noreferrer noreferrer noreferrer noreferrer" href="https://gis.stackexchange.com/questions/122636/prevent-postgis-topology-from-splitting-edges-on-line-insert" target="_blank">https://gis.stackexchange.com/questions/122636/prevent-postgis-topology-from-splitting-edges-on-line-insert</a></li><li>Source no2 indicating that Postgis does not support topology-network approach: <a rel="nofollow noopener noreferrer noreferrer noreferrer noreferrer" href="https://terragis.net/docs/other/MASTERING_POSTGIS.pdf" target="_blank">https://terragis.net/docs/other/MASTERING_POSTGIS.pdf</a> => p253</li></ol></div></div></div></div><blockquote style="margin:0px 0px 0px 40px;border:none;padding:0px"><blockquote style="margin:0px 0px 0px 40px;border:none;padding:0px"><div dir="ltr"><div dir="ltr"><div dir="ltr"><div><div>"Before we start working with topology, we need to discuss the key concepts behind the
PostGIS topological data model. PostGIS topology implementation is based on ISO standard
13249 - Information technology - Database languages - SQL multimedia and application packages -
Part 3: Spatial. The standard name is often abbreviated as ISO SQL/MM. This standard
defines two data models for topology: TopoGeometry and TopoNetwork; PostGIS
implements only the former."</div></div></div></div></div></blockquote></blockquote><blockquote style="margin:0px 0px 0px 40px;border:none;padding:0px"><blockquote style="margin:0px 0px 0px 40px;border:none;padding:0px"><div dir="ltr"><div dir="ltr"><div dir="ltr"><div><br></div></div></div></div></blockquote></blockquote><div dir="ltr"><div dir="ltr"><div dir="ltr"><div>I could verify this by testing on a basic local setup with QGIS and <b>Postgis version 3.3</b>. </div><div>I guess this feature was not added since. </div><div><br></div><div>I did not found any issues regarding this missing feature.</div><div><br></div><div>Is an issue already openned to request this new feature or should I create one ?</div><div><br></div><div>Best regards,</div><span>-- </span><br><div dir="ltr">Pierre HARDY<br></div></div></div></div></div></div></div></div>
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