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<[email protected]> wrote: > > Announcement: > > The GIS in the Cloud (App Engine + JTS) reference project is now > available at http://giscloud.appspot.com with the source code > available at http://giscloud.googlecode.com (documentation > forthcoming). > > While many GIS/spatial App Engine discussions center on the python SDK > (with pre-computing grids or geocells and heavy lifting done with set > membership in the datastore), this reference project uses the Java > Topology Suite (http://www.vividsolutions.com/jts/jtshome.htm) within > the App Engine server to demonstrate point-in-polygon and polygon-in- > polygon spatial queries. > > The GIS in the Cloud app is pure Java and was built with > > * Google App Engine SDK for Java > * Google Plugin for Eclipse > * Google Web Toolkit > * Google Web Toolkit API Libraries - Google Maps 1.0 Library > * Java Topology Suite > > The Java Topology Suite was ported to C++ and became GEOS, which was > embedded in PostgreSQL to become PostGIS, allowing users access to > spatial functions within SQL. While App Engine does not give us > spatial functions in GQL, the GIS in the Cloud app will demonstrate a > GQL/JTS combination to accomplish the same effect. > > The current version of the application does demonstrate use of the > datastore (TODO), but it does employ JTS to query point-in-polygon and > polygon-in-polygon. Single clicks on the map trigger the point-in- > polygon test (the point is the map center and the polygon is Salt Lake > County). With zoom or drag, the polygon-in-polygon test is triggered. > The first polygon is the map bounds and the second is Salt Lake > County. > > Future versions will use the datastore and be able to access OGC Well > Known Text (WKT) from which geometry can be created for features such > as: tracts, census block groups, census blocks, and parcels. > > > > > > > > > > -- Nick Johnson, App Engine Developer Programs Engineer Google Ireland Ltd. :: Registered in Dublin, Ireland, Registration Number: 368047 --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Google App Engine" group. To post to this group, send email to [email protected] To unsubscribe from this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/google-appengine?hl=en -~----------~----~----~----~------~----~------~--~---
