[mapserver-users] Raster rendering performance and zoom levels

[Frank Warmerdam]

Ian,

The normal approach to slow rendering at larger scales
is to build pyramids/overviews on large images.  This
can generally be accomplished something like:

  gdaladdo big.tif 2 4 8 16 32 64 128

The gdaladdo command should work on virtually all
GDAL supported raster formats.  There are also things you
could do to produce very specific overviews for the particular
rendering resolutions you want to produce.  But I'd suggest
first trying the above generic solution and see if it is
sufficient for your needs.  Some gdaladdo docs are available
at:

  http://www.gdal.org/gdaladdo.html

Best regards,


On Tue, Dec 13, 2011 at 3:21 PM, Ian Walberg <ian.walberg at airborne.aero> wrote:
>
>
> We have an application which is using php  mapscript to render maps at a
> number of different zoom levels, these zoom levels can be fixed and the maps
> are centered on a specific location.
>
>
>
> So we calculate the extent based on the zoom level and the current required
> center lat/long.
>
>
>
> The raster imagery we are using is approx. the same resolution as the max
> zoom (smallest extent) and in this case the map rendering is the fastest.
>
>
>
> As we zoom out and the extent increases the map rendering is slower, we are
> assuming this is because the imagery is being resized which is
> processor/memory intensive.
>
>
>
> Now the question,  how do we create imagery sets for each zoom level so that
> they are the required resolution and no re-sizing is required?
>
>
>
> We are using mapserver without a client to generate the images on a server.
>
>
>
> I hope this makes sense.
>
>
>
> Thanks
>
>
>
> Ian
>
>
>
>
>
>
> _______________________________________________
> mapserver-users mailing list
> mapserver-users at lists.osgeo.org
> http://lists.osgeo.org/mailman/listinfo/mapserver-users
>



-- 
---------------------------------------+--------------------------------------
I set the clouds in motion - turn up   | Frank Warmerdam, warmerdam at pobox.com
light and sound - activate the windows | http://pobox.com/~warmerdam
and watch the world go round - Rush    | Geospatial Software Developer