[postgis-users] Trouble with returning MultiPolygon on psql query

[Joseph Spenner]

I believe I may have overcomplicated my question.  My apologies.  I've come up with a much simpler explanation of the issue:
I have a MultiPolygon with 2 relatively simple polygons in it:
http://microflush.org/json/MultiPolygon.json

I've pulled out the 2 polygons from the above MultiPolygon below:

http://microflush.org/json/upper.json
http://microflush.org/json/lower.json
Any/all of the 3 above can be copied/pasted into a GeoJSON tester to view them:    http://geojsonlint.com/

I've stored the original MultiPolygon in PostgreSQL as described in my original post:
$ ogr2ogr -f "PostgreSQL" PG:"dbname=weatherzones user=postgres" "MultiPolygon.json" -nln polys
Here's how it looks in Postgres after the import:
polytest=# \d polys;
                                       Table "public.polys"
    Column    |          Type           |                        Modifiers                        
--------------+-------------------------+---------------------------------------------------------
 ogc_fid      | integer                 | not null default nextval('polys_ogc_fid_seq'::regclass)
 wkb_geometry | geometry(Geometry,4326) | 
 warnings     | character varying       | 
Indexes:
    "polys_pk" PRIMARY KEY, btree (ogc_fid)
    "polys_geom_idx" gist (wkb_geometry)

polytest=# 


When I try to query postgres using single points which lie in the lower polygon, I do not get rows returned.However, when I query using points which lie in the upper polygon, I get the row returned.
ie:
This point lies in the lower polygon, and this query returns no rows:
polytest=# select warnings from polys where ST_Intersects(ST_PointFromText('POINT( -116.024551 38.485773 )', 4326), wkb_geometry); 


This next point lies in the upper polygon, and this query returns a row, which is the MultiPolygon:
polytest=# select warnings from polys where ST_Intersects(ST_PointFromText('POINT( -114.879913 39.249129 )', 4326), wkb_geometry); 

Is there something wrong with my query, or perhaps the original MultiPolygon which can explain why a query with a point from the lower polygon won't return the MultiPolygon row?  I've done this with other MultiPolygons and have not had an issue like this.
Any help would be great.
Thanks!
Joseph Spenner


 

     From: Joseph Spenner <joseph85750 at yahoo.com>
 To: PostGIS Users Discussion <postgis-users at lists.osgeo.org> 
 Sent: Wednesday, September 9, 2015 12:10 PM
 Subject: Trouble with returning MultiPolygon on psql query
   
Hello, I have a file (source.json) containing 25 GeoJSON polygons with weather alerts, which I imported into postgres using the following command:
$ ogr2ogr -f "PostgreSQL" PG:"dbname=weatherzones user=postgres" "source.json" -nln polys

Here's how it looks in Postgres:
polytest=# \d polys;
                                       Table "public.polys"
    Column    |          Type           |                        Modifiers                        
--------------+-------------------------+---------------------------------------------------------
 ogc_fid      | integer                 | not null default nextval('polys_ogc_fid_seq'::regclass)
 wkb_geometry | geometry(Geometry,4326) | 
 warnings     | character varying       | 
Indexes:
    "polys_pk" PRIMARY KEY, btree (ogc_fid)
    "polys_geom_idx" gist (wkb_geometry)

polytest=# 

I can see it stored all of them:
polytest=# select count(*) from polys;
 count 
-------
    25
(1 row)

polytest=# 
However, when I try to use a ST_Intersects(ST_PointFromText('POINT(), I can't seem to get lines with MultiPolygons to return rows.  The regular Polygons seem to work fine, though.
For example, I have the following MultiPolygon in my table from Nevada: 
http://microflush.org/json/24.json
Using a validator site, such as http://geojsonlint.com/ , I can copy/paste that JSON into the interface and it looks like 2 adjacent shapes making up the MultiPolygon.
If I grab points from the upper section of the polygon, using something like http://itouchmap.com/latlong.html, I get rows returned:polytest=# select warnings from polys where ST_Intersects(ST_PointFromText('POINT( -114.543457 39.336281 )', 4326), wkb_geometry) limit 2; 
polytest=# select warnings from polys where ST_Intersects(ST_PointFromText('POINT( -115.658569 39.500297 )', 4326), wkb_geometry) limit 2; 

But if I use a point from the lower Polygon section of that MultiPolygon, I get zero:

polytest=# select warnings from polys where ST_Intersects(ST_PointFromText('POINT( -115.977173 38.548667 )', 4326), wkb_geometry) limit 2; 



Another example from Florida (a little more difficult to see, but same issue):http://microflush.org/json/06.json
polytest=# select warnings from polys where ST_Intersects(ST_PointFromText('POINT( -81.988228 27.034561 )', 4326), wkb_geometry) limit 2;

warnings 
----------
(0 rows)

The above point (-81.988228 27.034561) would spacially exist in this MultiPolygon.

However, in this example, it will only return rows if I pick a point inside the little polygon which shows up focused to the south of the much larger polygon (when you use the geojsonlin.com site to plot the whole thing).  For example, this point:
polytest=# select warnings from polys where ST_Intersects(ST_PointFromText('POINT( -81.9878 27.034 )', 4326), wkb_geometry) limit 2;(1 row)
So, it would seem the select statements which should return Multipolygons are not returning for all Polygons contained in the MultiPolygon.
Is there something I'm doing incorrectly with my queries?
Any help would be great.
Thank you!
Joseph Spenner




  
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