On Sat, Nov 17, 2018 at 10:16 AM Matt Hakim <[email protected]> wrote:
> Many thanks for your reply. I followed your thread on the devel list as > well. > > We are using Vector tiles so we can apply styling on the client > (openlayers) when a feature is selected. > For our scenario, if the output Vector tile just included the Polygons > that would have been rendered into the PNG anyway then that would be fine > (I think). > I had a bit of a look through the geotools StreamingRenderer.java and it > seems to deal with simplifying geometries and rendering shape primitives > using java's Graphics2D, StreamingRenderer interestingly also calls > TopologyPreservingSimplifier (similar to Vector output tiles). > Normal simplification is not topology preserving, see the Decimator class, it brutal, efficient and the geometries that come out of it are barely usable for rendering (but definitely not topologically valid) The only case you can find using the TopologyPreservingSimplifier is for building polygon offsets, in that case we need to start with a topologically valid geometry to compute the buffer. > Conceptually, could you capture the draw primitive requests going to > Graphics2D and instead output them in Vector tile format? Wouldn't that > work at the same speed as the Raster output tiles (or even faster as no > styling is applied)? Obviously I'm dreaming here (and it would take me > months to understand StreamingRenderer...) > I did not write the vector tiles module, had nothing to do with it actually, but if you check, it's using a lot of the rendering chain functionality. There is quite a bit of chatter about vector tiles efficiency on the net these weeks, you'll find that others are doing a non topological preserving simplification followed by a "make valid" operation, which tries to fix the errors. JTS, the library we use for geometries, does not provide such operation, but if you want you could look in the GEOS MakeValid operator (used by postgis for example) and replicate enough of it to use it in MVT, or sponsor someone (http://geoserver.org/support/) to do it on your behalf, well, that would be very welcomed. In parallel, I'm discussing on the devel list about doing clipping before simplification, in my tests it speeds up your use case quite a bit (mind, still slow). 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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