I was finally able to get this mostly working with a st_dumppoints in an inner
select. However, points in zone_wp_intersection are not ordered by the time
dimension (m coordinate):
"LINESTRING M (-95.7038708 38.9675286 1421442348000,-95.7028218 38.9720855
1421442366000,-95.704529 38.9656641 1421442338000)"
I can handle the sorting in the application tier but perhaps there is a better
way to order the points by time directly in the query?
select pkey, trip_id, zone_id, segment_id,
st_astext(ST_MakeLine((wp_pts).geom)) zone_wp_intersection,
startts, endts, startloc, endloc, probe_id, provider_id, movement_type, mode,
trip_dist_m, trip_mean_speed_metersph, trip_max_speed_metersph, is_start_home,
is_end_home, waypoints, match_cond
from (
select
st_dumppoints(waypoints) as wp_pts, -- get actual points in waypoints that
intersect with zone
pkey, trip_id, startts, endts, startloc, endloc, probe_id, provider_id,
movement_type, mode, trip_dist_m, trip_mean_speed_metersph,
trip_max_speed_metersph, is_start_home, is_end_home, waypoints, match_cond,
zone_id, zone_geom, segment_id from od1.v_trip_zone_segment where
startts>=TIMESTAMP '2015-01-16T12:20:29.000Z' and startts<TIMESTAMP
'2015-01-17T17:20:30.000Z' and endts<TIMESTAMP '2015-01-17T17:20:30.000Z' and
zone_id in ('kansas_303','kansas_601','kansas_603','kansas_604','kansas_10')
and segment_id in ('5062926','5062931','5062932','4062933','5055496')
and st_intersects(segment_geom, waypoints)
and st_contains(st_buffer(st_transform(waypoints,3857),
30.0),st_transform(segment_geom,3857))
and st_intersects(zone_geom, waypoints)
) as k
where st_intersects((wp_pts).geom, zone_geom)
group by pkey, trip_id, zone_id, segment_id,
startts, endts, startloc, endloc, probe_id, provider_id, movement_type, mode,
trip_dist_m, trip_mean_speed_metersph, trip_max_speed_metersph, is_start_home,
is_end_home, waypoints, match_cond
order by pkey, zone_id
Thanks,
Trang
From: [email protected]
[mailto:[email protected]] On Behalf Of Trang Nguyen
Sent: Friday, October 02, 2015 11:09 AM
To: PostGIS Users Discussion
Subject: Re: [postgis-users] Finding points of intersection of a linestring
with another multiolygon and linestring
Thanks Nicolas. Would I need to write a function to iterate over each point in
st_dumppoints to find whether a point is within the intersecting geometry or is
there a better way?
I’ve tried to do a select with st_dumppoints(waypoints) but finding that
performance is very slow: 289 sec vs 2 sec without st_dumppoints for a very
small time range and narrow set of input geometries. This is running on
postgres 9.4.1 and postgis 2.1.5.
Trang
From:
[email protected]<mailto:[email protected]>
[mailto:[email protected]] On Behalf Of Nicolas Ribot
Sent: Friday, October 02, 2015 2:20 AM
To: PostGIS Users Discussion
Subject: Re: [postgis-users] Finding points of intersection of a linestring
with another multiolygon and linestring
Hi,
Yes, you can use st_dumppoints to extract way's points and use these points in
a query with seg_wp_intersection and zone_wp_intersection to find intersections.
Nicolas
On 1 October 2015 at 20:27, Trang Nguyen
<[email protected]<mailto:[email protected]>> wrote:
I realize I didn’t clearly phrase my question:
- Is there a way to retrieve the points in the waypoints linestring
that intersects a polygon or another linestring without having to write a
function to traverse each point in waypoints to check whether the conditions
st_intersects(point, seg_wp_intersection) and st_intersects(point,
zone_wp_intersection) are met?
Any help on this would be greatly appreciated!
Thanks,
Trang
From:
[email protected]<mailto:[email protected]>
[mailto:[email protected]<mailto:[email protected]>]
On Behalf Of Trang Nguyen
Sent: Wednesday, September 30, 2015 10:28 PM
To: [email protected]<mailto:[email protected]>
Subject: [postgis-users] Finding points of intersection of a linestring with
another multiolygon and linestring
Hi forum,
I have a LINESTRING represent the waypoints of a trip through road segments
(LINESTRING) and zones (MULTIPOLYGON).
For each segment and zone, I would like to find out the points in the waypoints
which intersected the targeted zone/segment geometries. First and last
intersection point into and exiting the zone or segment would the sufficient
as well.
I can use st_intersection to find the intersection each of waypoints to segment
and zone geometries, but this returns a geometry that doesn’t necessarily
contain the subset of intersecting points in the linestring. The query will be
run on large datasets, so performance is an important consideration. GIST
indexes exist on all the geometries joined (zone_geom, segment_geom and
waypoints).
---------------------------
Query
---------------------------
select
st_transform(st_intersection(segment_geom, waypoints),4326)
seg_wp_intersection, -- need subset of points in waypoints that intersected
with segment_geom
st_transform(st_intersection(zone_geom, waypoints),4326) zone_wp_intersection,
-- need subset of points in waypoints that intersected with zone_geom
trip_id, waypoints, zone_id, segment_id
from od1.v_trip_zone_segment
where
startts>=TIMESTAMP '2015-01-16T12:20:29.000Z' and startts<TIMESTAMP
'2015-01-16T17:20:30.000Z' and endts<TIMESTAMP '2015-01-16T17:20:30.000Z' and
zone_id in
('kansas_303','kansas_601','kansas_603','kansas_604','kansas_10','kansas_11','kansas_9','kansas_310','kansas_311','kansas_315','kansas_301','kansas_302','kansas_307','kansas_306','kansas_305','kansas_204','kansas_201','kansas_3','kansas_2','kansas_1')
and segment_id in
('5062926','5062931','5062932','4062933','5055496','5063065','5062826','5062825','5062824','5062643','5062644','5062645','5062646','5055551','5062839','5062849','5062895','5063081')
and segment_mapversion='1501'
and st_intersects(segment_geom, waypoints)
and st_intersects(szone_geom, waypoints)
Thanks,
Trang
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