On Wed, Jun 24, 2020 at 4:33 PM carlo cancellieri < geo.ccancelli...@gmail.com> wrote:
> *Disabling that flag this error disappears and the tile is loaded.* > > Looking at this ( > http://www.tsusiatsoftware.net/jts/javadoc/com/vividsolutions/jts/simplify/DouglasPeuckerSimplifier.html > ) > page I see that actually it's possible to obtain invalid geometries if > setEnsureValid(false). > > Could that be the case? > > When do we need so aggressive simplification? May we've to expose also > that flag or put it as default to true? > The simplification is meant for rendering data. "topology preserving" simplification during rendering is so slow that you might as well not apply it at all, and render all the original points instead (tried, it's actually faster). Ensuring validity is also pretty slow, it comes with a lot of extra checks besides the one that you actually need (having at least 4 points to test orientation). When you are using pre-generalized, the generalization already happened once, so it's safe to turn off the extra simplification step in the database, we are already close enough to the target resolution. When not using it, a simple check can be added to the resulting geometries, if they are polygons with less than 4 points, it means they became the equivalent of a line going over itself (A to B and back to A, 3 coordinates, first and last superimposed), the geometry can be replaced with a simple variation adding a third point mid line, slightly above or below the A to B line (extra points for keeping it already in the right orientation for valid MVT encoding). > Maybe geoJson or other vectorial readers are currently supporting these > hints so they can be affected by the same problem? > Possibly... not sure, JSON tile encoding is not very common, not sure if there is anyone actually using it. That said, I'm not sure GeoJSON requires geometries to be topologically valid to start with, I see not mention of that in the standard. Cheers Andrea == GeoServer Professional Services from the experts! Visit http://goo.gl/it488V for more information. == Ing. Andrea Aime @geowolf Technical Lead GeoSolutions S.A.S. Via di Montramito 3/A 55054 Massarosa (LU) phone: +39 0584 962313 fax: +39 0584 1660272 mob: +39 339 8844549 http://www.geo-solutions.it http://twitter.com/geosolutions_it ------------------------------------------------------- *Con riferimento alla normativa sul trattamento dei dati personali (Reg. UE 2016/679 - Regolamento generale sulla protezione dei dati “GDPR”), si precisa che ogni circostanza inerente alla presente email (il suo contenuto, gli eventuali allegati, etc.) è un dato la cui conoscenza è riservata al/i solo/i destinatario/i indicati dallo scrivente. Se il messaggio Le è giunto per errore, è tenuta/o a cancellarlo, ogni altra operazione è illecita. Le sarei comunque grato se potesse darmene notizia. This email is intended only for the person or entity to which it is addressed and may contain information that is privileged, confidential or otherwise protected from disclosure. We remind that - as provided by European Regulation 2016/679 “GDPR” - copying, dissemination or use of this e-mail or the information herein by anyone other than the intended recipient is prohibited. If you have received this email by mistake, please notify us immediately by telephone or e-mail.*
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