Hi, No. this is because some of your polygons are not valid: for instance: select st_isvalid('POLYGON ((593921 5219610 803,593921 5219610 818,593921 5219620 818,593921 5219620 803,593921 5219610 803))'::geometry); NOTICE: Too few points in geometry component at or near point 593921 5219610 803 st_isvalid ------------ f (1 row)
you can control this with st_isvalid, st_isvalidReason and correct them with st_makeValid. Use only valid objects before processing them with Postgis functions. Nicolas On 29 October 2012 16:03, Ed Linde <edoli...@gmail.com> wrote: > Thanks Nicolas. Just about the error, is this because the line segments are > too close > and postgis 2.0 could not handle this? If so is there a workaround, even if > it means > slightly having to "perturb" each point's position to not run into this bug. > I was really hoping that the intersection of two polygonal shapes in 3D > would be fairly > simple in postgis 2.0 :( > > Ed > > > On Mon, Oct 29, 2012 at 4:00 PM, Nicolas Ribot <nicolas.ri...@gmail.com> > wrote: >> >> If the points are computed in the right order, you can store them and >> pass them to st_makeLine and st_makePolygon. >> If not, you can form a segment between 2 closest points and connect it >> to the closest points. >> >> On 29 October 2012 15:37, Ed Linde <edoli...@gmail.com> wrote: >> > Hi All, >> > Thanks for the tips! Just another thing, when I compute the "transition >> > points" on each edge (shown as red points in my pdf). >> > I need to join them to make a polygon. Wondering how I can connect them >> > together so that I start with a point and end on it >> > to form a closed polygon? >> > >> > Cheers, >> > Ed >> > >> > >> > On Mon, Oct 29, 2012 at 3:03 PM, Stephen Woodbridge >> > <wood...@swoodbridge.com> wrote: >> >> >> >> Hi Ed, >> >> >> >> Well if clarifies one thing at least, you can ignore Mike's st_Relate >> >> because 5 is not adjacent to a linear edge, it is only adjacent to a >> >> vertex, >> >> so st_touches should work fine. >> >> >> >> so you are looking for: >> >> >> >> 1. a specific triangle by id >> >> 2. that intersects triangle VC >> >> 3. and the triangles adjacent to triangle by id >> >> 4. and those that are contained in VC >> >> 5. sorted by distance to P1 limit 1 >> >> >> >> so something like: >> >> >> >> select id, the_geom >> >> from (select id, the_geom as adjacent >> >> from triangles >> >> where st_touches(the_geom, >> >> (select the_geom >> >> from triangles a, >> >> (select the_geom as vc >> >> from vc_table >> >> where id='p1') b >> >> where a.id=4)) c >> >> order by st_distance(c.the_geom, (select the_geom >> >> from points >> >> where id='p1')) asc limit 1; >> >> >> >> Untested, but should give you a model to work with. >> >> >> >> -Steve W >> >> >> >> >> >> >> >> On 10/29/2012 6:57 AM, Ed Linde wrote: >> >>> >> >>> Attached is a figure. Where the dotted line is the boundary of the >> >>> voronoi cell whose >> >>> generator is point P1. So triangle "4" intersects with the voronoi >> >>> boundary, but we are >> >>> interested in the adjacent triangles of triangle 4, which are closer >> >>> to >> >>> point P1. >> >>> For example, triangle 5. >> >>> >> >>> Hope this helps. >> >>> Cheers, >> >>> Ed >> >>> >> >>> On Mon, Oct 29, 2012 at 11:50 AM, Nicolas Ribot >> >>> <nicolas.ri...@gmail.com >> >>> <mailto:nicolas.ri...@gmail.com>> wrote: >> >>> >> >>> Could you draw a figure ? >> >>> >> >>> Nicolas >> >>> >> >>> On 29 October 2012 11:03, Ed Linde <edoli...@gmail.com >> >>> <mailto:edoli...@gmail.com>> wrote: >> >>> > Hi All, >> >>> > Thanks for the suggestions. >> >>> > For 1) I will look into how ST_touches works and see if it can >> >>> pick up all >> >>> > the adjacent polygons to >> >>> > the one I have. And also look into Mike's suggestion on >> >>> ST_relate...though I >> >>> > must admit it looks >> >>> > more complex. >> >>> > For 2) I will try to clarify it a bit more... its harder to do >> >>> without a >> >>> > figure :) but here goes. >> >>> > >> >>> > Lets say we have a point Q which is the generator of a voronoi >> >>> cell. Now I >> >>> > compute the >> >>> > intersection between the voronoi cell boundaries and my >> >>> triangulation (Set >> >>> > of polygons) >> >>> > using ST_intersect. Once I have these triangles.. I say pick >> >>> one >> >>> triangle T >> >>> > that is >> >>> > intersecting the voronoi cell boundary of Q. >> >>> > For all the triangles adjacent to T, I need to know which >> >>> triangles are >> >>> > INSIDE the voronoi >> >>> > boundary (closer to Q) and which adjacent triangles are just >> >>> OUTSIDE the >> >>> > voronoi >> >>> > boundary (farther from Q). I am basically testing for a certain >> >>> property by >> >>> > "shrinking" the >> >>> > voronoi cell (closer to Q) and another property when >> >>> "expanding" >> >>> the voronoi >> >>> > cell (away from Q). >> >>> > Just need to make this division of triangles. Haven't thought >> >>> of >> >>> a nice way >> >>> > to do this in postgis 2.0 >> >>> > So any suggestions would greatly help. >> >>> > >> >>> > Thanks, >> >>> > Ed >> >>> > >> >>> > On Mon, Oct 29, 2012 at 10:15 AM, Mike Toews <mwto...@gmail.com >> >>> <mailto:mwto...@gmail.com>> wrote: >> >>> >> >> >>> >> On 29 October 2012 21:33, Ed Linde <edoli...@gmail.com >> >>> <mailto:edoli...@gmail.com>> wrote: >> >>> >> > Hi All, >> >>> >> > I need help with 2 hard problems. I store triangles in a >> >>> table >> >>> as >> >>> >> > POLYGON. >> >>> >> > >> >>> >> > 1. I want to know for a given triangle, which triangles >> >>> share >> >>> an edge >> >>> >> > (adjacent) with this triangle. >> >>> >> >> >>> >> Sounds like you have a finite element mesh with nodes and >> >>> elements. >> >>> >> You can use ST_Relate with pattern 'FF2F11212' to pick out >> >>> elements >> >>> >> that share the same edge. This DE-9-IM is sort-of a custom >> >>> ST_Touches, >> >>> >> but only takes linear boundary overlaps. So if you have a >> >>> table >> >>> >> "elements", and you want to find ones that touch ID 567: >> >>> >> >> >>> >> SELECT elements.* >> >>> >> FROM elements, elements as e >> >>> >> WHERE e.id <http://e.id> = 567 AND >> >>> >> >>> >> ST_Relate(elements.geom, e.geom, 'FF2F11212'); >> >>> >> >> >>> >> I'm not certain about your second question. >> >>> >> >> >>> >> -Mike >> >>> >> _______________________________________________ >> >>> >> postgis-users mailing list >> >>> >> postgis-users@postgis.refractions.net >> >>> <mailto:postgis-users@postgis.refractions.net> >> >>> >> >>> >> http://postgis.refractions.net/mailman/listinfo/postgis-users >> >>> > >> >>> > >> >>> > >> >>> > _______________________________________________ >> >>> > postgis-users mailing list >> >>> > postgis-users@postgis.refractions.net >> >>> <mailto:postgis-users@postgis.refractions.net> >> >>> >> >>> > http://postgis.refractions.net/mailman/listinfo/postgis-users >> >>> > >> >>> _______________________________________________ >> >>> postgis-users mailing list >> >>> postgis-users@postgis.refractions.net >> >>> <mailto:postgis-users@postgis.refractions.net> >> >>> >> >>> http://postgis.refractions.net/mailman/listinfo/postgis-users >> >>> >> >>> >> >>> >> >>> >> >>> _______________________________________________ >> >>> postgis-users mailing list >> >>> postgis-users@postgis.refractions.net >> >>> http://postgis.refractions.net/mailman/listinfo/postgis-users >> >>> >> >> >> >> _______________________________________________ >> >> postgis-users mailing list >> >> postgis-users@postgis.refractions.net >> >> http://postgis.refractions.net/mailman/listinfo/postgis-users >> > >> > >> > >> > _______________________________________________ >> > postgis-users mailing list >> > postgis-users@postgis.refractions.net >> > http://postgis.refractions.net/mailman/listinfo/postgis-users >> > >> _______________________________________________ >> postgis-users mailing list >> postgis-users@postgis.refractions.net >> http://postgis.refractions.net/mailman/listinfo/postgis-users > > > > _______________________________________________ > postgis-users mailing list > postgis-users@postgis.refractions.net > http://postgis.refractions.net/mailman/listinfo/postgis-users > _______________________________________________ postgis-users mailing list postgis-users@postgis.refractions.net http://postgis.refractions.net/mailman/listinfo/postgis-users