[Mapserver-users] raster image server: optimal performance

[Hubert Fröhlich]

Hello list,

I want to use MapServer 3.6.3 as a raster server for rectified aerial photos
, working on a Linux box (SuSE 8.0), I have also gdal.

For testing, I worked with a dataset of jpg's (plus worldfiles) or
geotiffs.

I have a test dataset of aerial photos (jpg plus worldfile, alernatively
geotiff) of an area 40 x 25 km in 1km-square tiles with resolution 40
cm, i.e. the tiles are 2500x2500 pixels, about 800 tiles.

To get things working at all, I proceeded the usual way
for raster images setting up an index
shapefile (e.g. with gdaltindex). So far, everything OK ...


Now I want to speed up things, as my original dataset covers 200x350 km,
all in 40cm resolution. (IN jpeg 80 GByte, in GeoTiff about 400 GByte!),
   in 1km-squares that would mean 70000 tiles. The files are stored in a
simple file system.

a) I tried out jpeg's vs (uncompressed) geotiffs. With the test dataset,
jpegs (also diskspace-saving!) seemed to perform slightly better. Can
anybody share the experience or give me hints about the best performing
data format?

b) What effect on MapServer response time does the tile size have? Any
recommendations on the list for optimal tile size (bigger means less
tiles) for best performance? Any dependencies on the data format?

c) At the moment, I use b/w photos. What changes do I face in
performance if I switch to color?


Thank you

Hubert
-- 
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Dr.-Ing. Hubert Fröhlich			
Bezirksfinanzdirektion München 			
Alexandrastr. 3, D-80538 München, GERMANY
Tel. :+49 (0)89 / 2190 - 2980
Fax  :+49 (0)89 / 2190 - 2459
hubert.froehlich at bvv.bayern.de