[mapserver-users] Projection takes less time than no projection ?

[Clément MONIER]

Hi All,

I'm using MapServer to generate tiles to overlay on a GoogleMaps base layer.
My data files are WGS84 shapefiles.

So my current mapfile was looking like :

MAP
...
PROJECTION "init=epsg:3785" END
...
LAYER
...
PROJECTION "init=epsg:4326" END
...
END
...
END

I was wondering about improving response time by disabling on-the-fly projection.
So I did pre-project my shp into spherical Mercator first.
And my new mapfile now looks like :

MAP
...
PROJECTION    "proj=merc"    "a=6378137"    "b=6378137"    "lat_ts=0.0"    "lon_0=0.0"    "x_0=0.0"    "y_0=0"    "k=1.0"    "units=m"    "nadgrids=@null"    "no_defs" END
...
LAYER
...
END
...
END

I do get the same  tiles.
But when asking a single tile using both mapfile, I noticed that the response time was higher (about +10%) when the second mapfile was used !

Do you have any idea about what's going on ?

Thanks  & Regards

Clément
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