[Mapserver-users] gdaladdo

[Frank Warmerdam]

Manuel Marichal Pérez wrote:
> Hi all.
>  
> I've got an application which deal with large TIFF's raster images. I 
> considered to use GDAL to improve the
> performance (gdaladdo & gdaltndex). I succesfully compiled GDAL in my 
> machine. Also I recompiled
> mapserver with "--without-tiff" and "--with-gdal" options.
>  
> Then I used gdaladdo with one of my tiff images in order to make a TIFF 
> image with many levels. Right.
>  
> Now, what must I do with my "map" file to get the correct image be 
> displayed as the user changes the scale?.

Manuel,

If you have a GeoTIFF file with many overview levels (as generated with
gdaladdo), you don't need to do anything special to make MapServer use the
overviews.  It will do so automatically (down in GDAL) when requests are for
overviews for which an overview has sufficient resolution.

As noted by Vincent, tiling your dataset may also be helpful for very large
datasets.

Note that using overviews within a GeoTIFF file (or other GDAL supported
format) means you don't have to use the normal MapServer technique of having
several different resolution LAYER objects each with MINSCALE and MAXSCALE set
to select on depending on the resolution.

Best regards

-- 
---------------------------------------+--------------------------------------
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 Programmer for Rent