Thank you for your answer! This is much clearer now. So, I will continue to live with floating precision operations for the moment.
Best regards, man Le ven. 6 juil. 2018 à 22:34, Sandro Santilli <[email protected]> a écrit : > On Fri, Jul 06, 2018 at 11:25:16AM +0200, Marc-Antoine Nüssli wrote: > > Hi there, > > > > First, I want to say a big thanks to Sandro Santilli and all people who > > work on the topology features. It looks like it becomes now mature enough > > to be used for production applications and this is really great to manage > > geo-data much more consistently than with simple geometries (especially > > when you deal a lot with territorial partitions like in my case) > > Thanks for the feedback! > > > I have a question regarding the precision value that we have to provide > > when creating a topology. I am not sure to understand its purpose. > > Somehow, I would have expected that it would be used when computing new > > nodes positions, for example resulting from an intersection, but from my > > tests it seems it is not the case (see my example below) > > Do you have some links or other infos that would describe how & when this > > global topology precision parameter is used? > > Using it for nodes position is planned. Doing so will need introduction > of the concept of fixed-precision operations which are still unavailable > in PostGIS. Such operations would first enforce snapping of input > geometries to a fixed-precision grid and then ask GEOS to perform the > operation using that grid. > > Right now PostGIS Topology only uses the "precision" value to snap > incoming lines and vertices to existing nodes and vertices when using > toTopoGeom or the underlying TopoGeo_addPoint, TopoGeo_addLinestring > and TopoGeo_addPolygon and not overriding the global value. > > --strk; >
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