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

[Masanao Yajima]

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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