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We have recently been transitioning our company mapping system from Google map, first to deCarta and then to OpenLayers. We have found that OpenLayers and deCarta are remarkably slower than Google Maps when many elements (several thousand) are added to the map (pins with bubbles on click). Google has the Marker Manager which appears to make it faster, but what I can't figure out is how this cuts down the memory usage or whatever to make it perform so much better. It's driving me nuts because we do the same thing with both OL and deCarta as we do with Google and the others are so slow. Does anyone have any experience in working with these systems?

I know that Google is the massive giant of mapping technology and therefore has put enormous amounts of money into the system, so it's not surprising that it's faster. I just want to know HOW if at all possible.

Thanks!

Andrew Christensen
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Any Marker/Geoemtry you put into the map via the OL API has to be downloaded to the browser and then rendered in the browser's memory.

If you have many geometries that you render onto the map, you can make an extra image layer with just these geometries. You can do that by using a WMS like Geoserver. Geoserver plays very nice with OpenLayers and is a pretty fast WMS. So you can combine the public a background layer like OSM or GoogleMaps with layers from your own WMS.

This approach might not work for clickable markers, but will improve speed when you show any painted geometries like polygons etc. on the map.

Greetings, Steve

alfonx
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    MapServer generally is still a lot faster than GeoServer, according to the [OSGeo benchmarks](http://www.slideshare.net/gatewaygeomatics.com/wms-performance-shootout-2010) – Martijn Mar 04 '11 at 15:16
  • Any genuine WMS will play nice with OpenLayers - MapServer or GeoServer or whatever. That's the point of using open standards! – MarkJ Apr 08 '11 at 12:49
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I take it you are using one of the classes in OpenLayers.Strategy, such as Filter or Cluster, to reduce the number of markers that are actually displayed? I haven't used Google maps, but it sounds as though marked manager does the same kind of thing. Ultimately, both libraries are constrained by the same browser limitations when it comes to rendering large number of dom objects.

John Powell
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The main reason why Google Maps perform better when displaying that many markers is because they use HTML5 Canvas to render the markers instead of an image node for each marker. When the browser needs to re-paint the map when panning or zooming, it has to re-paint all the elements in the layer container. Less elements, better the performance. OpenLayers has some support for Canvas, but I'm not aware of any marker renderers in Canvas. You will also have to detect clicks on markers on your own, since you no longer have a node pr marker to click on.

Where I work we generate an image server-side and use an old-school image map to make areas of the image clickable. It's a solution we made long before Canvas existed, so I wouldn't recommend it, but it also works in older browsers. If the markers are quite static I'd rather use a WMS like others have suggested, or implement it on your own with a Canvas.

Beware, the Canvas spec is still a working draft, and not available in older browsers: http://caniuse.com/canvas

Bill the Lizard
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gregers
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Google maps and Open Layers are just JS-Framework for the Browser-Client. That shouldn't make much difference. I think it is Google Maps server infractstructure that is a little bit more effective. Also Marker Manager isn't a very good software (isn't it open-source enthusiast solution?) altough it is JS and client-side but I've clobbered myown cluster-manager using a space-filling-curve and it works fairely good. I bet it is better then Marker Manager because there are other cluster-solution in the web too and to me they are better.

Micromega
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I've experienced the same issue with deCarta, the browser goes slower with 800 approx pins elements (with bubble on click), I asked Krishna Vanka(who no longer works at deCarta) about this but I don't get any solution so we build a new filter by zoom parameter and coordinates painting elements and caching offscreen elements so we can get on memory about 2000 pins, of course, is not the best way but it works.

The problem in our system (GPS WebApp) with geometries and pins it's that are drawn by users so extra image layers is not a possibility.

nimblerex
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nerdcoder
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