[postgis-users] PostGIS to calculate time spent within polygon

[Masanao Yajima]

Thank you for your response.

However, would it be possible to elaborate on the 2nd part?
If my reading of the manual is correct,
I believe st_intersection is not implemented to handle the 4th dimension.

Masanao Yajima

On Tue, Oct 6, 2009 at 6:47 AM, Suhr, Ralf <Ralf.Suhr at itc-halle.de> wrote:

>  Hello Masanao Yajima,
>
>
>
> for db-design you can go with ogr2ogr (GPX -> PostGIS). Ogr2ogr creates
> point and line geometrys from gpx files. In case of linestring you have to
> add the 4. Dimension from the point table.
>
> A optimal query would be the intersection from gps-linestrings and your
> polygon area. The result can be many sublinestrings with start and end time.
>
>
>
> Gr Ralf
>
>
>
> *Von:* postgis-users-bounces at postgis.refractions.net [mailto:
> postgis-users-bounces at postgis.refractions.net] *Im Auftrag von *Masanao
> Yajima
> *Gesendet:* Montag, 5. Oktober 2009 23:03
> *An:* postgis-users at postgis.refractions.net
> *Betreff:* [postgis-users] PostGIS to calculate time spent within polygon
>
>
>
> Dear PostGIS users
>
> I am new to PostGIS and I would like expert opinion on how to deal with my
> situation.
>
> I have 2D GPS data and time associated with each points and they represents
> line of a trip.
> I also have few geographic polygon data representing some area on a map.
>
> what I want to get out is length of time that is spent within polygon area
> for a trip.
>
> What is the optimal way to design a database and what kind of query would
> you use to get such a number.
>
> One constraint is the time interval for GPS is not accurate so sampling
> rate vary alot with in a trip.
>
> I thought of using time as 4th dimension but I believe st_intersection is
> not implemented on the 4th dimension..
>
> I could do this by bruit force but I am looking for something fast.
>
> I appreciate your help.
>
> --
> Masanao Yajima
>
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>


-- 
Masanao Yajima
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