Hi,
in my toying with the big geotiff image (for those who lost the preview
shows, a 1.4GB tiff extracted from the Bluemarble 500m raster) I've
discovered that image mosaics can really hurt.
The original 1.4GB image takes a few seconds to be shown even without overviews (say 10-15 seconds for the first request, that has two images
to be loaded in mapbuilder), and then no more than 2/4 seconds for subsequent requests.
If I add overviews to that image, it becomes 2GB (I used the OverviewEmbedder with -s $data_dir\coverages\na_2004_08\na_2004_08.tiff -f 2 -n 10 -c 256 -t 512,512 -Xmx1500M), first access is only 2-3
seconds, zooming and panning takes maybe 0.5 seconds with a bit slower
access on the most zoomed in requests.
I then used the CoverageTiler to create a 20x20 tiles mosaic, and built
the mosaic, tried to preview it, removed the limitation of 300 tiles,
and then tried to preview again. This time the first image loading took... so much time that I just killed it.
So, as a rule of thumb, we should tell people to go pyramid beyond
a few tiles in a mosaic, right? The only catch is, mosaic handles
overlappings, pyramid does not? So in case of overlap, first mosaic,
then tile cut with the CoverageTiler with regular tiles, and then
mosaic again and do pyramid?
Cheers
Andrea