Cameron Shorter wrote:
Shaun,
Some answers from Chris inserted below:
Udig-devel,
Anyone know what compression formats are available, or what state of
development they are in?
Shaun Kolomeitz wrote:
Cameron,
Do you have a contact in uDIG land who has been working on the Java
local database file format ?
What I am trying to determine is whether uDIG will (in the future) be
able to access a local (off-lined) feature dataset consisting of feature
data and features classes (much like ESRI ArcMaps GeoDatabase). The
current Shapefile format has a nasty restriction in text column width if
255 chars. The other "nice" thing would be the ability to extract
(cookie-cut) imagery related to the project area of interest (for taking
out into the field). Having this data in a compressed format such as
JPEG2000 or ECW/JPGE2000 would also be a plus.
I notice there are some discussions of JPEG2000 in the java lists which
suggests that someone is working on it. Anyone able to give an update?
Simone is the one who's been working on it. He can likely give you more
information.
Or should I just take this question holus-bolus to the uDig mail list ?
Many thanks,
Shaun
_
Shaun,
I don't think Chris would mind me forwarding on an email he sent earlier.
Chris, do you have an order of magnitude estimate for the effort
required to incorporate the H2 Database into Geotools (and hence UDig).
I don't think it should be too bad. Justin started an H2 datastore,
see: http://svn.geotools.org/geotools/trunk/gt/modules/unsupported/h2/
I believe it's working, but not entirely done. He can go in to the
details of what's needed.
The only major thing lacking is a spatial index for H2. That's the only
unknown quantity. I wrote out what it may involve and links to relevant
resources at http://docs.codehaus.org/display/GEOS/H2+Spatial+Index The
most interesting is this thread in H2 awhile ago:
http://h2database.com/ipowerb/index.php?showtopic=212
I wouldn't think it would take more than three or four weeks, since most
all the pieces are there. But I could be wrong, as there are unknown
qualities, and a lot of pieces to fit together.
Chris
Chris Holmes wrote:
<snip>
H2 is a pure java database - http://www.h2database.com/ - that's fast
and secure. We've been experimenting with Blasby's 'spatial db in a
box' with it - http://docs.codehaus.org/display/GEOS/SpatialDBBox -
automatic binding of JTS geometry objects to fully implement simple
features for sql. It's a few megs big and can act as a real database,
and is pure java so you can ship it with applications, embedded in uDig
or GeoServer. This is huge, since if there's not a real database
available then there aren't many other options, and real databases are
hard for normal users to install. Getting a spatial h2 could be a nice
challenge for you guys, and indeed could be a cool open source project
to call your own (we'd be happy to let you claim it though most ideas
are ours, since we've got enough on our plate). It should be really
useful in other contexts, like any java based gis app could make use of
it. It'd be like ESRI's personal DB, but it wouldn't have any
artificial limits. It'd become a widely used piece in the java stack.
All that really remains on it is to write a good spatial index for it,
and then it should be a really powerful database.
One thing to note to your potential funders is that working on a
versioning wfs datastore means that the capability will be available in
uDig without much additional work. Which presents a real, usable WFS
client, that can function completely off the network. It downloads the
full dataset once, and then lets you go to work. I don't believe the
piece of doing updates to the versioning WFS when offline coming back
online should be hard at all - it would just store the queue of
transactions. The tricky part is the conflicts, but an initial version
could just do something blunt like refuse to update and make you resolve
conflicts by hand.
--
Chris Holmes
The Open Planning Project
http://topp.openplans.org
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