Andrea Aime ha scritto: > Hi, > first off, sorry for cross posting, yet the topic is > of interest of both communities. > > During the last couple of months I've been working in the > background to make the streaming renderer + shapefile > datastore work at a similar level of performance as the shapefile renderer. > > The reason for that is simple, to avoid the double maintenance > the shapefile renderer code imposes on the rendering subsystem. > With the patches I've committed today (after testing them in > my checkout for a few weeks, the biggest one for longer) > the streaming renderer should have become more or less > as fast as the shapefile one in most common cases, but one, > and faster in another. > > The slower case is when the shapefile to be painted is > disproportionately bigger than the area to be painted. > The shapefile renderer here uses a trick, it keeps a binary > map of the pixels where anything has already been drawn, > and any feature smaller than a pixel gets compared to it, > and not drawn at all if the pixel has been touched once > already. > This gives it a 10x speedup compared to the streaming > renderer, but at the price of breaking solid any thematic > map: if you think about a map in which there are a number > of tiny geometries to be colored according to their attributes > and, say, all the red ones are read fist, you'll just get > a red map, because the geometries with other colors just > won't be painted over the red ones. > Basically this way the shapefile renderer gives the user > a fast overview of where things are, but breaks the actual > thematic distribution. > > The case in which the streaming renderer is faster instead > is mapping with multiple feature type styles to get a layering > effect: the streaming renderer will allocate multiple back buffers > and do a single scan of the data source, whilst the shapefile > renderer will scan the data source one time per feature type style > (so the streaming renderer speedup is proportional to the number > of feature type styles involved). > > I would like to just drop the usage of the shapefile renderer > and move it to unsupported land before we go RC. > > Opinions?
Forgot one important bit: can people try out both renderers out of today's trunk (or later) and see how they work for them? Do you get similar results to mine? What discrepancies, and where? Afaik uDig already dropped the ShapefileRenderer. Can uDig people confirm that? Cheers Andrea -- Andrea Aime OpenGeo - http://opengeo.org Expert service straight from the developers. ------------------------------------------------------------------------------ Come build with us! The BlackBerry® Developer Conference in SF, CA is the only developer event you need to attend this year. Jumpstart your developing skills, take BlackBerry mobile applications to market and stay ahead of the curve. Join us from November 9-12, 2009. Register now! http://p.sf.net/sfu/devconf _______________________________________________ Geoserver-devel mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/geoserver-devel
