On Tue, Apr 14, 2009 at 10:09:43AM -0300, Chris Adams wrote: > I don't think a lot of experimentation is required, I would implement it > as such: > > g = [view port width / cell size][view port height / cell size] > > For each point, p: > px <- convert p to view port PX > px <- floor(px / cell size) > if px in g is valid and g[px.x][px.y] not defined: > g[px.x][px.y] <- p > > for each cell in g, if defined: > render g[x][y] as marker > > I'd run this on zoom end, and move end (after pan completes, or after > mouse button released) > > The only configuration is the cell size, where 1 would mean there would > be at most 1 marker for a given pixel, and the values increase from > there. A higher value would mean better preformance, a lower would have > a higher density of points.
This is basically how the clustering strategy works. -- Chris > - Chris > > alts...@yahoo.com wrote: > > I think the proper solution would be to limit number of markers depending > > on zoom level and visible map region. If you're at high zoom level and > > markers are too close to each other, they will overlap and you do not > > really see anything. Solution is to render not all markers but skip markers > > if distance between them is too close (probably distance should be > > determined by experimenting). When user zooms in, app should communicate > > with server and request more markers for visible region. > > > > opengts tracking system has the very same problem. I was going to implement > > something like I explained above myself but it's quite low on my priority > > list. But if you have the solution, I'd like to use it ;) > > > > Serg > > > > > > > > ----- Original Message ---- > > > >> From: willson <talentp1...@yahoo.com.cn> > >> To: users@openlayers.org > >> Sent: Tuesday, April 14, 2009 12:26:40 PM > >> Subject: Re: [OpenLayers-Users] How to add many(>400) markers to the map? > >> > >> > >> > >> > >> Hi, > >> if you were using Geoserver and wms, dynamic symbolizer could help you. > >> Check the following out: > >> > >> http://blog.geoserver.org/2008/12/08/dynamic-symbolizers-part-1/ > >> > >> - mika - > >> > >> > >> willson kirjoitti: > >> > >>> Hi, > >>> try to search mailing list for strategies, performance. I have the same > >>> > >> problem not solved yet. It looks I will have to render at server site. > >> > >>> Michal > >>> > >>> > >>> Hi everyone, this is the first post on this forum. I have search the > >>> problem > >>> > >> on the forum, but find no anwser. > >> > >>> What I need to solve is: I have more than 400 points need to show on the > >>> map, > >>> > >> these points query my db every 10 secs, and change their color according > >> to the > >> return value. > >> > >>> I use the openlayers.layer.marker to implement, but in ie the markers > >>> make the > >>> > >> map so slow when zooming. > >> > >>> Then I move to openlayers.layer.vector, but it's even slower than marker. > >>> Any suggestion in such "Adding large and dynamically changed markers" > >>> > >> situation? > >> > >>> > >>> > >>> hi, render in serverside(may be wms) can improve the performance much, > >>> but how > >>> > >> to make markers dynamically change color? Any solution? > >> > >>> > >>> > >> _______________________________________________ > >> Users mailing list > >> Users@openlayers.org > >> http://openlayers.org/mailman/listinfo/users > >> > >> > >> > >> hi, > >> Yes, I am using geoserver and wms. I have look at the link, but it may be > >> not > >> the answer. Since the data in my db change frequently, and the marker > >> need to > >> reflect these changes. For example , I have a table, and a column named > >> "kpi", > >> when kpi<0.01, the marker's color is green, else is red. It may be not an > >> "sld" > >> issue. > >> > >> -- > >> View this message in context: > >> http://n2.nabble.com/How-to-add-many%28%3E400%29-markers-to-the-map--tp2631715p2632376.html > >> Sent from the OpenLayers Users mailing list archive at Nabble.com. > >> > >> _______________________________________________ > >> Users mailing list > >> Users@openlayers.org > >> http://openlayers.org/mailman/listinfo/users > >> > > > > > > > > > > _______________________________________________ > > Users mailing list > > Users@openlayers.org > > http://openlayers.org/mailman/listinfo/users > > > > > > > > > _______________________________________________ > Users mailing list > Users@openlayers.org > http://openlayers.org/mailman/listinfo/users -- Christopher Schmidt MetaCarta _______________________________________________ Users mailing list Users@openlayers.org http://openlayers.org/mailman/listinfo/users
