On Tue, Jul 14, 2009 at 11:33 PM, Stuart Moffatt wrote:
> Nick,
>
> What about the Blob idea. Blobs are byte arrays of unlimited size (according
> to the docs). That doesn't sound like its limited to 1MB.
Blobs in the datastore are part of the entity, and entities are
limited to 1MB. In future, t
On Tue, Jul 14, 2009 at 11:30 PM, Stuart Moffatt wrote:
> Ah, thought there was a catch. Will have to consider an RTree implementation
> (any live examples with datastore entities?), but it would be nice to use
> JTS' STRtree.
You may also want to check out the approaches used by GeoModel for
Pyt
Ah, thought there was a catch. Will have to consider an RTree implementation
(any live examples with datastore entities?), but it would be nice to use
JTS' STRtree.
What about storing the index as a file in WEB-INF?
Stuart
On Tue, Jul 14, 2009 at 4:23 PM, Nick Johnson (Google) <
nick.john...@go
Are you aware that Datastore entities are limited to 1MB each? If you
want to implement an R-Tree, you're probably best off implementing the
tree using datastore entities.
-Nick Johnson
On Tue, Jul 14, 2009 at 11:15 PM, Stuart Moffatt wrote:
> After a little more thought I am ready to try an imp
After a little more thought I am ready to try an improved method to
getting a geospatial index on App Engine.
Concept: Use a serialized STRtree
Possible implementations:
1) Roll my own STRTree package to implement Serializable, which is
part of App Engine's whitelist. Convert to a byte array an
All,
Beta 0.6 of http://giscloud.appspot.com is live. Details below.
This version hits the datastore for the county entity (rather than in-
lining as in previous versions), yanks out 242KB worth of well-known
text in the form of POLYGON(())) describing
the county at a high resolution, parses the
[Note: cross-posting back to gae for java to pick up an earlier thread,
further discussions should remain on the main app engine group]
Brian,
After Nick's comments I dove into finding out more about this and came
across your Arc2Earth Cloud services and some comments you made about
"quadtrees pa
hi stuart
great work getting JTS to run on GAE.
Have you started to look at how you would port those JTS indexes to
the GAE datastore? for me (and others), the hard part with geospatial
queries in GAE isn't the geometry intersection ops (although JTS is a
welcome addition for this), its how you
Nick,
More information on JTS indexes:
1) STRTree - a packed R-Tree that does not support insert/delete once built
2) QuadTree - slower than STRTree but supports insert/delete
http://jump-pilot.sourceforge.net/pdfs/jts_secrets_foss4g2007.pdf
Stuart
On Fri, Jul 10, 2009 at 10:39 AM, Stuart Moff
Nick,
Correct, as in, not yet. The reference app just parses well-known text on
the fly to create geometry (server side only), and tests that geometry
(which is usually complex) against incoming coordinates (so far only points
and map bounds). Next stop, figuring out the right kind of index and it
Hi Stuart,
Am I correct in inferring that you're not storing geospatial indexes
persistently at all, then? This seems impractical for the App Engine
architecture, and for the scale it is intended to support.
-Nick Johnson
On Fri, Jul 10, 2009 at 5:29 PM, Stuart Moffatt wrote:
> Nick,
>
> First,
Nick,
First, there was a typo in my announcement that I just realized. The second
last paragraph should state that the "current version of the application
does NOT demonstrate use of the datastore", that is, I am still in the
process of implementing fetches of WKT from my entities, but that's the
Hi Stuart,
Very nice!
Out of curiosity, what indexing scheme does JTS use? Are you building
an R-Tree or other tree based structure on top of the datastore, or
are you using a hilbert-curve type approach?
-Nick Johnson
On Fri, Jul 10, 2009 at 8:03 AM, Stuart Moffatt wrote:
>
> Announcement:
>
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