[OpenLayers-Users] very slow map using WKT Multipolygon with a lot of Points

[Fabrizio Buratta]

2012/11/18 Sergeant_york <electronicpanda at gmail.com>

> Codes seems okay to me. The only thing that can cause performance issue
> could
> be transforming from 4326 to map projection but after initializing
> geometries it shouldn't affect the performance.
>
> In my opinion, you can:
>
> 1- Try to change renderers to get best performance.
>

as said in the openlayers 2.11 release notes I put the following line
before any Vector and
it is way more fast dragging which was one of my targets, so really good
point.

OpenLayers.Layer.Vector.prototype.renderers = ["SVG2", "VML", "Canvas"];



> 2- Simplify geometries with respect to zoom levels.
>


Is there a method to simplify geometries automatically?


> 3- Try to keep fill opacity to 0 and stroke opacity to 1 (should be tested)
>

It does not change performances


> 4- Draw only the place inside the bounding box
>

what do you mean , I should reduce the bbox?


>
> These are the things which I can say, but unfortunately with many vertexes
> openlayers (even in chrome) gives a bit bad performance. So don't expect to
> get results like desktop applications.
>


Yes, it is still very slow loading the vertexes.... I'm thinking about
reducing the polygon vertexes, do you know any algorithm or any way to
simplify polygons?

 thanks


-- 
Fab

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