Is it possible to get some sort of idea about how the raster data is being
organised
and what scales is it being asked to support?
In all my experience the critical factor with raster data for display rendering
is the issue of the size of the storage tile relative to the average display
window.
This was investigated back in the 1980s quite well by Peter Lamb of the CSIRO
Division of
Information Technology in Australia: his paper "Tiling Very Large Rasters" is
worth
reading. I have put a draft version of the report on my website:
www.spatialdbadvisor.com/files/TilingVeryLargeRasters.pdf
for you to peruse. I used a paper Peter produced to design the original
www.whitepages.com.au
raster (tiled) database.
On Sun, 30 Jan 2011 13:24:34 +1100, Sunny Teo <[email protected]> wrote:
Hi Regina,
Thanks for the lead on this.
It opens up the light and the room for discussion. Well, as far as I know,
Oracle Georaster is not good for serving purpose and on top of it, that
takes awful amount of time to load the data into Oracle. I assume that its
not the case with PG Raster.
The other issue is, even if one dont want to do store the multiband (say 8
band) imagery into the PG Raster for the Speed issue, can we target to link
up the Cache into this? If GWC or Tile Cache jpg/png tiles can be kept here
and then publish... it will be nice. Again, the issue will be speed ... or
some may argue the fact the it defeats the purpose of Cache which is suppose
to be non "ram" required serving.
my only wish, that one day we should be able to easily load the images into
PG Raster and publish into a web application and get a performance/speed as
good as any image servers.
btw, it was a news to me that GeoServer dont support PG Raster yet... I hope
they are working on it now...
Thank you;
Sunny
On Sun, Jan 30, 2011 at 6:30 AM, Paragon Corporation <[email protected]> wrote:
Sunny,
Good question. I suspect it will be worse at least at the moment (just as
PostGIS was worse when it first came out than reading from shapefile). How
much worse I'm not sure. If you try and see speed issues, we can tackle
them, but it hasn't really been our main focus.
I suspect no one has tested it extensively as far as dishing out large
datasets. The primary focus of PostGIS Raster is for analysis and then
secondary is the rendering. That is not to say it will work badly or we
don't care about rendering speed, just that the GDAL drivers etc. needed by
Mapserver probably still have a few wrinkles which would make it suboptimal
for that kind of work. The more people use it and find issues, the faster
issues will be addressed since we would have data points to go by.
As far as GeoServer goes, I recall reading a thread where Chris Holmes said
he would work on a PostGIS Raster support for GeoServer, but not sure where
that is down the pipe, but to my knowledge, GeoServer does not YET support
PostGIS raster.
Hope that helps,
Regina
------------------------------
*From:* [email protected] [mailto:
[email protected]] *On Behalf Of *Sunny Teo
*Sent:* Saturday, January 29, 2011 3:44 AM
*To:* [email protected]
*Subject:* [postgis-users] PostGIS Raster Performance
List,
Can anyone comment on the "Performance" of the PostGIS Rater or WKTRaster ?
If you were to serve this onto a web application, how effective are they?
Well, I'm talking of very large datasets like 10GB each and 100 of them. How
does it compare with serving the images as files directly.. from a GeoTIFF,
ECW, Sid, etc. (obviously using Geoserver/Mapserver or some specialized
image serving solution)
Been searching all over the web for the answers, but no luck.
Hope to get some insights from the users.
Thank you;
Sunny.
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