Hi Jorge,
Please see the notes on Polygons:
http://wiki.apache.org/solr/SolrAdaptersForLuceneSpatial4#JTS_.2BAC8_WKT_.2BAC8_Polygon_notes
This bullet in particular is relevant:
• The standard way to specify a rectangle in WKT is a Polygon -- WKT
doesn't have a rectangle shape. If you want to specify a Rectangle via WKT
(instead of the Spatial4j basic non-WKT syntax), you should take care to
specify the coordinates in counter-clockwise order, the WKT standard. If this
is done wrong then the rectangle will go the opposite direction longitudinally,
even if it means one that spans nearly the entire globe (>180 degrees width).
OpenLayers seems to not honor the WKT standard here, and depending on the
corner you drag the rectangle from, might use a clockwise order. Some systems
like PostGIS don't care what the ordering is, but the problem there is that
there is then no way to specify a rectangle that has >= 180 width because there
would be ambiguity. Spatial4j follows the WKT spec.
You aren't the first to have run into this problem. Perhaps I should add a
mode in which you cannot specify rectangles with a width >= 180 but in exchange
your rectangle will always go the way you intended (assuming always < 180)
without having to worry about coordinate order.
~ David Smiley
On Oct 8, 2012, at 5:25 AM, Jorge Suja wrote:
> Hi everyone,
>
> I've been playing around with the new spatial search functionalities
> included in the newer versions of solr (solr 4.1 and solr trunk 5.0), and
> i've found something strange when I try to find a point inside a polygon
> (particularly inside a square).
>
> You can reproduce this problem using the spatial-solr-sandbox project that
> has the following config for the fields:
>
> /[...]
> <fieldType name="geohash" class="solr.SpatialRecursivePrefixTreeFieldType"
> units="degrees" />
> [...]
> <field name="geohash" type="geohash" indexed="true" stored="true"
> multiValued="false" />
> [...]/
>
> I'm trying to find the following document:
>
> /<doc>
> <str name="id">G292223</str>
> <str name="name">Dubai</str>
> <str name="geohash">55.280000 25.252220</str>
> </doc>
> /
> I want to test if this point is located inside a polygon so i'm using the
> following query:
>
> /q=geohash:"Intersects(POLYGON((55.180000 25.352220,55.380000
> 25.352220,55.380000 25.152220,55.180000 25.152220,55.180000 25.352220)))"/
>
> As you can see, it's a small square that contains the point described
> before. I get some results, but that document is not there, and the ones
> returned are wrong since they are not even inside the square.
>
> /<result name="response" numFound="8" start="0">
> <doc>
> <str name="id">G1809498</str>
> <str name="name">Guilin</str>
> <str name="geohash">110.286390 25.281940</str>
> </doc>
>
> [...]/
>
> However, if i change a little bit the shape of the square (just changed a
> little bit one corner), it returns the result as expected
>
> /q=geohash:"Intersects(POLYGON((55.180000 25.352220,*55.480000*
> 25.352220,55.380000 25.152220,55.180000 25.152220,55.180000 25.352220)))"/
>
> Now it returns a single result and it's OK
>
> /<result name="response" numFound="1" start="0">
> <doc>
> <str name="id">G292223</str>
> <str name="name">Dubai</str>
> <str name="geohash">55.280000 25.252220</str>
> </doc>
> </result>/
>
>
> If i use a bbox with the same size and position than the first square, it
> returns correctly the document.
>
> /q=geohash:"Intersects(55.180000 25.152220 55.380000 25.352220)"
>
> <result name="response" numFound="1" start="0">
> <doc>
> <str name="id">G292223</str>
> <str name="name">Dubai</str>
> <str name="geohash">55.280000 25.252220</str>
> </doc>
> </result>/
>
> If you draw another polygon such a triangle it works well too.
>
> I've tested this against different points and it's always the same, it seems
> that if you draw a straight square (or rectangle),
> it can't find the point inside it, and it returns wrong results.
>
> Am i doing anything wrong?
>
> Thanks in advance
>
> Jorge
>
>
>
> --
> View this message in context:
> http://lucene.472066.n3.nabble.com/Solr-4-spatial-search-point-intersects-polygon-tp4012402.html
> Sent from the Solr - User mailing list archive at Nabble.com.
