Hello dear mailing list. I'm having troubles with postgis-topology Please see the history of this mail to see the self contained example, which involves 4 polygons crashing the toTopoGeom function
Cheers, Rémi-C @ STRK : Ok I post this to mailing list. Thanks for your answer. As I'm a new user to postgis-topology, I keep track of what I'm missing in doc, and I would be glad to add some high level documentation, provided that you check that I don't write stupid things. A simple tutorial about postgis-topology using open data could maybe do it? I guess for somebody used to topology concept in GIS it much be much easier to understand postgis-topology. I find your presentation of 2011 is a good starting point. I already have latest stable release for GEOS (3.3.8), but tomorrow I can try to go to dev version. I'll fill ticket tomorrow as well ;-) Cheers, Rémi-C 2013/7/31 Sandro Santilli <[email protected]> > On Wed, Jul 31, 2013 at 05:13:38PM +0200, Rémi Cura wrote: > > Hello , and thank you for your answer. I realized that mbr is "maximum > > bouding rectangle"... > > "minimum" > > > I was guessing that you stored face geometry to avoid to compute it each > > time, and couldn't find the right place in documentation saying > otherwise. > > No, I'm not storing it. > Up for a patch for documentation ? > > > I'm still trying to work with postgis-topology extension :-) > > > > By the way, do you prefer me to ask question directly or on the postgis > > mailing list? > > Mailing list please. > > > I have encoutered a problem using the extension, while loading data. > [...] > > I get an error : "ERROR: Spatial exception - geometry intersects edge > 1" > > . > > I don't understand why I get an error as this is a legitimate spatial > > partitionning data. All geometry are valid according to postgis and qgis > > They don't st_overlaps, but they do st_intersects (boundary) > > > > Is this because postgis topology doesn't support having areal inside > areal? > > Sounds like a robustness issue. Could you please file a ticket with > the data ? Things may change by reducing the tolerance, or using a newer > GEOS (snap operation has been made somewhat better in current dev branch). > > --strk; > > > > > > Thanks a lot for your time, > > > > Cheers, > > > > Rémi-C > > > > 2013/7/26 Sandro Santilli <[email protected]> > > > > > On Wed, Jul 24, 2013 at 02:01:29PM +0200, Rémi Cura wrote: > > > > Hello, > > > > I'm trying the postgis topology extension, and I'm running into > > > something i > > > > don't understand while re-enacting your example given in 2011 > > > presentation. > > > > > > > > First problem : > > > > If I get it correctly, we create 3 points, then 3 edges between these > > > > points. After this a face it automatically created. > > > > Then when creating the 4th edge (crossing as a diagonal), the strange > > > > behaviour happens : > > > > it correctly creates a new face, but the 2 faces are squares, and not > > > > triangles. > > > > > > > > I checked in the "face" table, and both faces are the same (and > > > represent a > > > > square polygon). A normal behaviour would be to have triangles. > > > > I used the function polygonize() to update the face, with no changes. > > > > I updated GEOS, no changes > > > > > > You might be confusing the "mbr" field of the face table > > > with the face geometry. See if ST_GetFaceGeometry helps. > > > > > > > Second problem : > > > > It is miscellaneous, but when deleting the postgis-topology postgres > > > > extension, the topology schema created aren't removed (the 'conf' > schema > > > > using your example). > > > > As it has no senses without the extension, I guess we could expect > to be > > > > deleted along. > > > > > > Someone actually asked to go the other way: forbid deletion if tables > > > depend on it. So this is an open issue. > > > > > > > NB 0 : > > > > the "face" table : the 2 polygon are identical > > > > 0;"" > > > > 2;"POLYGON((10 -90,10 20,100 20,100 -90,10 -90))" > > > > 1;"POLYGON((10 -90,10 20,100 20,100 -90,10 -90))" > > > > > > Right, those are the minimum bounding rectangles. > > > > > > --strk; > > > > > >
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