[mapserver-dev] Server-side Simplication Speed-up

Lime, Steve D (DNR) Steve.Lime at state.mn.us
Thu Mar 22 13:25:45 PDT 2012

Another idea would be to examine the queryObj that hangs off the mapObj (e.g. map->query). If
the type is MS_QUERY_IS_NULL then it's a rendering operation. Query maps are a special case but
they're often combined with other presentation so that's probably ok.

Might at least be able to test with that... 


-----Original Message-----
From: mapserver-dev-bounces at lists.osgeo.org [mailto:mapserver-dev-bounces at lists.osgeo.org] On Behalf Of Daniel Morissette
Sent: Thursday, March 22, 2012 3:20 PM
To: mapserver-dev at lists.osgeo.org
Subject: Re: [mapserver-dev] Server-side Simplication Speed-up

Could we add msLayerSetSimplifyResolution() that could be called to turn on/off the simplify stuff? Passing a valid resolution at the beginning of a rendering pass would enable it, and a resolution of 0 in other cases would disable it and return the original coordinates.

On 12-03-22 3:59 PM, Paul Ramsey wrote:
> Sandro working on MapNik says that this change
> https://github.com/mapnik/mapnik/issues/1136
> running an "appropriate" st_simplify on the geometries before sending 
> them over the wire to the renderer, gave up to 75% speedups on 
> rendering complicated items.
> In order to try it out on MapServer, the PostGIS driver needs to know 
> two things:
> - what's the resolution being rendered to? this I can pick up out of 
> the mapObj easily I think, tracing back up from the layerObj passed 
> into the driver
> - is this a rendering call to the driver, or a feature access call?
> this is harder... I need to distinguish between calls to the driver 
> that are going to use the features for rendering and those that are 
> going to send them back to the requester as data. Is there an obvious 
> global way to figure this out from the driver level?
> P.
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Daniel Morissette
Provider of Professional MapServer Support since 2000

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