Am 2012-10-14 11:43, schrieb Jukka Rahkonen:
Frank Broniewski <brfr <at> metrico.lu> writes:
Hi,
I have a directory with appr. 2800 aerial images, each 1kmx1km. I'm
using this source for a Mapserver WMS layer. Unfortunately the amount of
data to process is way too much for a Mapserver WMS service.
Now I want to create larger overview images where the aerial images are
combined together. The route I wanted to was
1) build a VRT from the images
2) use gdal_translate to get a new geotiff with a smaller size (pixel wise)
Is this a valid route to go?
Yes it is.
I have configured Mapserver orthoimage layers so that Mapserver does not
ever need to to open more that about 12-16 original tiff images per one
screenful of output. We have 12000x12000 pixel images with 0.5 m pixel
size. Four such side by side makes 48000 pixels and if they are pressed
to 1000 pixel wide output image the pixel size in output is roughly 25 m.
Therefore I have prepared resampled layer with 25 m pixel size which
is used for small scale output.
Prepare new set of images, each covering 50x50 kilometers or more
with 50 times bigger pixels than the originals. Create scale
dependent GROUP layer for Mapserver and you should get good speed.
Naturally you must run gdaladdo for the resampled images and perhaps
make one more re-resampled set if your coverage is very big.
-Jukka Rahkonen-
Many thanks,
Frank
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Hi Jukka,
thanks for your answer. This is what I wanted to hear :-)
My whole area is not larger than 83km x 58km or 166.000 x 116.000 Pixel,
so its not as big as yours. Your numbers are really helpful, thanks
again. This should get me going ...
Frank
--
Frank BRONIEWSKI
METRICO s.à r.l.
géomètres
technologies d'information géographique
rue des Romains 36
L-5433 NIEDERDONVEN
tél.: +352 26 74 94 - 28
fax.: +352 26 74 94 99
http://www.metrico.lu
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