Re: [postgis-users] Postgis overlapping two linestrings
Hi Ani, Have you looked into st_intersects() ? and st_intersection() ? http://postgis.refractions.net/docs/ST_Intersects.html James On 22 November 2013 16:17, Ani Alamo wrote: > Hi! > I need a specific function to get if two linestring overlaps. e.g. > Linestring 1 is Point (0, 0) : Point (10, 0) Linestring 2 is Point (0, 0) : > Point (3, 0) > > In this case I need "true" result because LineString 1 overlaps in different > points like 0,0 1,0 2,0 & 3,0. I dont need the common points, I only need if > two linestring overlaps or not. I tried with this function in postgis... > > overlaps(buffer(LINESTRING1, 0.001), buffer(LINESTRING2, 0.001)) > I create a buffer on both linestrings... but muy problem is some times works > better, some times not. > > Can you help me please? > > Thanks! > > ___ > postgis-users mailing list > postgis-users@lists.osgeo.org > http://lists.osgeo.org/cgi-bin/mailman/listinfo/postgis-users ___ postgis-users mailing list postgis-users@lists.osgeo.org http://lists.osgeo.org/cgi-bin/mailman/listinfo/postgis-users
Re: [postgis-users] Postgis overlapping two linestrings
Uhm... exactly I have this linestrings: LINESTRING(2.118932325 41.398745991,2.168720219 41.385631938) LINESTRING(2.142346041 41.398526436,2.81541 41.409216161) intersections gives me: GeometryCollection: GEOMETRYCOLLECTION EMPTY intersects gives me: false but when I see the line drawn on map I see both lines intersect in a little "section" (strectch). But really when I use intersects or intersection functions gives me "unavailable intersection"... and when I use OVERLAPS function overlaps(buffer(LINESTRING1, 0.001), buffer(LINESTRING2, 0.001)) also gives me "false". Another ideas please?? 2013/11/22 James David Smith > Hi Ani, > > Have you looked into st_intersects() ? and st_intersection() ? > > http://postgis.refractions.net/docs/ST_Intersects.html > > James > > On 22 November 2013 16:17, Ani Alamo wrote: > > Hi! > > I need a specific function to get if two linestring overlaps. e.g. > > Linestring 1 is Point (0, 0) : Point (10, 0) Linestring 2 is Point (0, > 0) : > > Point (3, 0) > > > > In this case I need "true" result because LineString 1 overlaps in > different > > points like 0,0 1,0 2,0 & 3,0. I dont need the common points, I only > need if > > two linestring overlaps or not. I tried with this function in postgis... > > > > overlaps(buffer(LINESTRING1, 0.001), buffer(LINESTRING2, 0.001)) > > I create a buffer on both linestrings... but muy problem is some times > works > > better, some times not. > > > > Can you help me please? > > > > Thanks! > > > > ___ > > postgis-users mailing list > > postgis-users@lists.osgeo.org > > http://lists.osgeo.org/cgi-bin/mailman/listinfo/postgis-users > ___ > postgis-users mailing list > postgis-users@lists.osgeo.org > http://lists.osgeo.org/cgi-bin/mailman/listinfo/postgis-users > ___ postgis-users mailing list postgis-users@lists.osgeo.org http://lists.osgeo.org/cgi-bin/mailman/listinfo/postgis-users
Re: [postgis-users] Postgis overlapping two linestrings
I tried this function: intersects(buffer(LINESTRING1, 0.001), buffer(LINESTRING2, 0.001)) Always gives me "false" result. I don't know what to do! 2013/11/22 Ani Alamo > Uhm... exactly I have this linestrings: > LINESTRING(2.118932325 41.398745991,2.168720219 41.385631938) > LINESTRING(2.142346041 41.398526436,2.81541 41.409216161) > > intersections gives me: > GeometryCollection: GEOMETRYCOLLECTION EMPTY > > intersects gives me: > false > > but when I see the line drawn on map I see both lines intersect in a > little "section" (strectch). But really when I use intersects or > intersection functions gives me "unavailable intersection"... and when I > use OVERLAPS function > overlaps(buffer(LINESTRING1, 0.001), buffer(LINESTRING2, 0.001)) also > gives me "false". > > Another ideas please?? > > > 2013/11/22 James David Smith > >> Hi Ani, >> >> Have you looked into st_intersects() ? and st_intersection() ? >> >> http://postgis.refractions.net/docs/ST_Intersects.html >> >> James >> >> On 22 November 2013 16:17, Ani Alamo wrote: >> > Hi! >> > I need a specific function to get if two linestring overlaps. e.g. >> > Linestring 1 is Point (0, 0) : Point (10, 0) Linestring 2 is Point (0, >> 0) : >> > Point (3, 0) >> > >> > In this case I need "true" result because LineString 1 overlaps in >> different >> > points like 0,0 1,0 2,0 & 3,0. I dont need the common points, I only >> need if >> > two linestring overlaps or not. I tried with this function in postgis... >> > >> > overlaps(buffer(LINESTRING1, 0.001), buffer(LINESTRING2, 0.001)) >> > I create a buffer on both linestrings... but muy problem is some times >> works >> > better, some times not. >> > >> > Can you help me please? >> > >> > Thanks! >> > >> > ___ >> > postgis-users mailing list >> > postgis-users@lists.osgeo.org >> > http://lists.osgeo.org/cgi-bin/mailman/listinfo/postgis-users >> ___ >> postgis-users mailing list >> postgis-users@lists.osgeo.org >> http://lists.osgeo.org/cgi-bin/mailman/listinfo/postgis-users >> > > ___ postgis-users mailing list postgis-users@lists.osgeo.org http://lists.osgeo.org/cgi-bin/mailman/listinfo/postgis-users
Re: [postgis-users] Postgis overlapping two linestrings
You may try http://postgis.net/docs/ST_SharedPaths.html Cheers, Rémi-C 2013/11/22 Ani Alamo > I tried this function: > intersects(buffer(LINESTRING1, 0.001), buffer(LINESTRING2, 0.001)) > Always gives me "false" result. > > I don't know what to do! > > > 2013/11/22 Ani Alamo > >> Uhm... exactly I have this linestrings: >> LINESTRING(2.118932325 41.398745991,2.168720219 41.385631938) >> LINESTRING(2.142346041 41.398526436,2.81541 41.409216161) >> >> intersections gives me: >> GeometryCollection: GEOMETRYCOLLECTION EMPTY >> >> intersects gives me: >> false >> >> but when I see the line drawn on map I see both lines intersect in a >> little "section" (strectch). But really when I use intersects or >> intersection functions gives me "unavailable intersection"... and when I >> use OVERLAPS function >> overlaps(buffer(LINESTRING1, 0.001), buffer(LINESTRING2, 0.001)) also >> gives me "false". >> >> Another ideas please?? >> >> >> 2013/11/22 James David Smith >> >>> Hi Ani, >>> >>> Have you looked into st_intersects() ? and st_intersection() ? >>> >>> http://postgis.refractions.net/docs/ST_Intersects.html >>> >>> James >>> >>> On 22 November 2013 16:17, Ani Alamo wrote: >>> > Hi! >>> > I need a specific function to get if two linestring overlaps. e.g. >>> > Linestring 1 is Point (0, 0) : Point (10, 0) Linestring 2 is Point (0, >>> 0) : >>> > Point (3, 0) >>> > >>> > In this case I need "true" result because LineString 1 overlaps in >>> different >>> > points like 0,0 1,0 2,0 & 3,0. I dont need the common points, I only >>> need if >>> > two linestring overlaps or not. I tried with this function in >>> postgis... >>> > >>> > overlaps(buffer(LINESTRING1, 0.001), buffer(LINESTRING2, 0.001)) >>> > I create a buffer on both linestrings... but muy problem is some times >>> works >>> > better, some times not. >>> > >>> > Can you help me please? >>> > >>> > Thanks! >>> > >>> > ___ >>> > postgis-users mailing list >>> > postgis-users@lists.osgeo.org >>> > http://lists.osgeo.org/cgi-bin/mailman/listinfo/postgis-users >>> ___ >>> postgis-users mailing list >>> postgis-users@lists.osgeo.org >>> http://lists.osgeo.org/cgi-bin/mailman/listinfo/postgis-users >>> >> >> > > ___ > postgis-users mailing list > postgis-users@lists.osgeo.org > http://lists.osgeo.org/cgi-bin/mailman/listinfo/postgis-users > ___ postgis-users mailing list postgis-users@lists.osgeo.org http://lists.osgeo.org/cgi-bin/mailman/listinfo/postgis-users
Re: [postgis-users] Postgis overlapping two linestrings
I hope you are not runnning into a very annoying precision issue. If it were the case, you may want to try the patch I just submitted to GEOS, (https://github.com/Remi-C/libgeos). and then you would check like this : decompose line A into points (ST_DumPPoints) if any point is on line B : true else decompose line B into points if any point of B in on line A return true else return false (you chekc "point on line" with st_intersects) Cheers, Rémi-C 2013/11/22 Rémi Cura > You may try > http://postgis.net/docs/ST_SharedPaths.html > > Cheers, > > Rémi-C > > > 2013/11/22 Ani Alamo > >> I tried this function: >> intersects(buffer(LINESTRING1, 0.001), buffer(LINESTRING2, 0.001)) >> Always gives me "false" result. >> >> I don't know what to do! >> >> >> 2013/11/22 Ani Alamo >> >>> Uhm... exactly I have this linestrings: >>> LINESTRING(2.118932325 41.398745991,2.168720219 41.385631938) >>> LINESTRING(2.142346041 41.398526436,2.81541 41.409216161) >>> >>> intersections gives me: >>> GeometryCollection: GEOMETRYCOLLECTION EMPTY >>> >>> intersects gives me: >>> false >>> >>> but when I see the line drawn on map I see both lines intersect in a >>> little "section" (strectch). But really when I use intersects or >>> intersection functions gives me "unavailable intersection"... and when I >>> use OVERLAPS function >>> overlaps(buffer(LINESTRING1, 0.001), buffer(LINESTRING2, 0.001)) also >>> gives me "false". >>> >>> Another ideas please?? >>> >>> >>> 2013/11/22 James David Smith >>> Hi Ani, Have you looked into st_intersects() ? and st_intersection() ? http://postgis.refractions.net/docs/ST_Intersects.html James On 22 November 2013 16:17, Ani Alamo wrote: > Hi! > I need a specific function to get if two linestring overlaps. e.g. > Linestring 1 is Point (0, 0) : Point (10, 0) Linestring 2 is Point (0, 0) : > Point (3, 0) > > In this case I need "true" result because LineString 1 overlaps in different > points like 0,0 1,0 2,0 & 3,0. I dont need the common points, I only need if > two linestring overlaps or not. I tried with this function in postgis... > > overlaps(buffer(LINESTRING1, 0.001), buffer(LINESTRING2, 0.001)) > I create a buffer on both linestrings... but muy problem is some times works > better, some times not. > > Can you help me please? > > Thanks! > > ___ > postgis-users mailing list > postgis-users@lists.osgeo.org > http://lists.osgeo.org/cgi-bin/mailman/listinfo/postgis-users ___ postgis-users mailing list postgis-users@lists.osgeo.org http://lists.osgeo.org/cgi-bin/mailman/listinfo/postgis-users >>> >>> >> >> ___ >> postgis-users mailing list >> postgis-users@lists.osgeo.org >> http://lists.osgeo.org/cgi-bin/mailman/listinfo/postgis-users >> > > ___ postgis-users mailing list postgis-users@lists.osgeo.org http://lists.osgeo.org/cgi-bin/mailman/listinfo/postgis-users
Re: [postgis-users] Postgis overlapping two linestrings
ST_Relate() is an interesting and versatile function: http://postgis.org/docs/ST_Relate.html (also illustrated at http://workshops.boundlessgeo.com/postgis-intro/de9im.html ) But maybe your problem is one of tolerance/roundoff-error On 22/11/2013 8:17 AM, Ani Alamo wrote: Hi! I need a specific function to get if two linestring overlaps. e.g. Linestring 1 is Point (0, 0) : Point (10, 0) Linestring 2 is Point (0, 0) : Point (3, 0) In this case I need "true" result because LineString 1 overlaps in different points like 0,0 1,0 2,0 & 3,0. I dont need the common points, I only need if two linestring overlaps or not. I tried with this function in postgis... overlaps(buffer(LINESTRING1, 0.001), buffer(LINESTRING2, 0.001)) I create a buffer on both linestrings... but muy problem is some times works better, some times not. Can you help me please? Thanks! ___ postgis-users mailing list postgis-users@lists.osgeo.org http://lists.osgeo.org/cgi-bin/mailman/listinfo/postgis-users -- Martin Feuchtwanger feu...@shaw.ca Vancouver, BC V5N 1J6 http://members.shaw.ca/geomatics.developer ___ postgis-users mailing list postgis-users@lists.osgeo.org http://lists.osgeo.org/cgi-bin/mailman/listinfo/postgis-users
Re: [postgis-users] Postgis overlapping two linestrings
On 23 November 2013 05:50, Ani Alamo wrote: > Uhm... exactly I have this linestrings: > LINESTRING(2.118932325 41.398745991,2.168720219 41.385631938) > LINESTRING(2.142346041 41.398526436,2.81541 41.409216161) > > intersections gives me: > GeometryCollection: GEOMETRYCOLLECTION EMPTY > > intersects gives me: > false > > but when I see the line drawn on map I see both lines intersect in a little > "section" (strectch). No, these lines don't intersect, they are somewhat parallel to each other, but not at all even close to touching. You might be confusing another pair of lines. > But really when I use intersects or intersection > functions gives me "unavailable intersection"... and when I use OVERLAPS > function > overlaps(buffer(LINESTRING1, 0.001), buffer(LINESTRING2, 0.001)) also gives > me "false". > > Another ideas please?? Avoid using buffer for proximity analysis. Try using ST_DWithin instead: SELECT ST_Distance(A::geography, B::geography) AS dist_m, ST_Distance(A::geometry, B::geometry) AS dist, ST_DWithin(A::geography, B::geography, 700) AS within_m, ST_DWithin(A::geometry, B::geometry, 0.006) AS within FROM (SELECT 'LINESTRING (2.118932325 41.398745991, 2.168720219 41.385631938)'::text AS A, 'LINESTRING (2.142346041 41.398526436, 2.81541 41.409216161)'::text as B ) as f; -[ RECORD 1 ]- dist_m | 623.162866494591 dist | 0.00575141350513493 within_m | t within | t -Mike ___ postgis-users mailing list postgis-users@lists.osgeo.org http://lists.osgeo.org/cgi-bin/mailman/listinfo/postgis-users
