Peter, You wrote: "The problem with the timestamps come up in the case of the tracks. For waypoints - a point feature - you can store the geographic coordinates in the geometry, and the timestamp as an attributte. But with tracks - which intuitively should be a linestring - you can have timestamps for every and each node, so you can't store that as an attributte. The current implementation of the GPX datastore in the repository extends JTS to use 4 coordinates for every point, so it can store the timestamp along with the geometry, and I could even define a compound CRS with 4 axes (lat, lon, elevation, time), but no other part of the library suports this construct. For example if I try to load a track into udig, it will try to transform it to an other CRS, but that will fail."
This is a very interesting problem. I think it could possible be solved by storing a String attribute that holds a String in a parseable format (maybe comma separated). You could associate the first timestamp in the string with the first node in the LineString. It would then take specialized code in the client application (like OpenJUMP or UDig) to parse and use this information. In OpenJUMP we could do this with a plug-in. It's a rather nifty idea, as it would (for example) allow you to calculate the speed of the receiver between points in the track. Landon On Tue, May 20, 2008 at 11:12 AM, Jody Garnett <[EMAIL PROTECTED]> wrote: > Bolla, Péter wrote: >>> >>> Here is an alternative; you can ask a JTS CoordinateSequence to hold your >>> own Coordinates that can include x,y,z and a time stamp. While this is >>> easier with ISO Geometry (where your CRS could literally be x,y,time) you >>> can certaintly fake it with JTS right now. >> >> Exactly that's what I did, but the other geotools modules and uDig didn't >> like it... :( > > Do you have specifics? It sounds fine to me; you may uncover some bugs along > the way .. but the OracleDataStore does similar tricks when working with > x,y,z,m data (ie from LRS datasets). I think the other fun bit of info would > be a new GeoTools Function to "grab" the data out of the geometry so it can > be worked with as part of styling etc... > > How about something like "ordinate"; it could also be used to extract just > the x and y ordinates.. consider the following CQL expressions: > - ordinate( the_geom, 3 ) --> List<Joda_Time> > - min( ordinate( the_geom, 3 ) ) ---> minimum timestamp > - max( ordinate( the_geom, 3 ) ) ---> maximum timestamp > > Cheers, > Jody > ------------------------------------------------------------------------- This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2008. http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/ _______________________________________________ Geotools-devel mailing list Geotools-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/geotools-devel
