[#MDEV-7514] GIS: PointOnSurface returns NULL instead of the point

[MDEV-7514] GIS: PointOnSurface returns NULL instead of the point Created: 2015-01-27 Updated: 2020-11-09 Resolved: 2015-03-15
Status:	Closed
Project:	MariaDB Server
Component/s:	GIS
Affects Version/s:	N/A
Fix Version/s:	10.1.4

Type:

Bug

Priority:

Critical

Reporter:

Elena Stepanova

Assignee:

Alexey Botchkov

Resolution:

Fixed

Votes:

Labels:

gis

Attachments:

gis1.png

Issue Links:

Relates
relates to	~~MDEV-7509~~	Testing for GIS extensions	Closed

Description

10.1 tree
MariaDB [test]> SELECT ST_AsText(ST_PointOnSurface(ST_PolyFromText('POLYGON((-70.916 42.1002,-70.9468 42.0946,-70.9754 42.0875,-70.9749 42.0879,-70.9759 42.0897,-70.916 42.1002))')));
+-----------------------------------------------------------------------------------------------------------------------------------------------------------------+
\| ST_AsText(ST_PointOnSurface(ST_PolyFromText('POLYGON((-70.916 42.1002,-70.9468 42.0946,-70.9754 42.0875,-70.9749 42.0879,-70.9759 42.0897,-70.916 42.1002))'))) \|
+-----------------------------------------------------------------------------------------------------------------------------------------------------------------+
\| NULL \|
+-----------------------------------------------------------------------------------------------------------------------------------------------------------------+
1 row in set (0.00 sec)

PostGIS
pgis=# SELECT ST_AsText(ST_PointOnSurface(ST_PolyFromText('POLYGON((-70.916 42.1002,-70.9468 42.0946,-70.9754 42.0875,-70.9749 42.0879,-70.9759 42.0897,-70.916 42.1002))')));
st_astext
-----------------------------------
POINT(-70.9510231824279 42.09385)
(1 row)

The shape is rather simple (see the picture).

Comments

Comment by Ian Gilfillan [ 2015-02-05 ]

The function doesn't seem to return a point under any circumstances. It even fails for a single point:

SET @g = ST_GEOMFROMTEXT('Point(0 5)');

SELECT ST_ASTEXT(ST_POINTONSURFACE(@g));

+----------------------------------+

| ST_ASTEXT(ST_POINTONSURFACE(@g)) |

+----------------------------------+

| NULL                             |

+----------------------------------+

Comment by Alexey Botchkov [ 2015-03-15 ]

Fixing patch: http://lists.askmonty.org/pipermail/commits/2015-March/007595.html

Comment by Deepak Vohra [ 2020-11-09 ]

The function still returns

NULL

in version 10.5.

SELECT ST_AsText(ST_PointOnSurface(ST_PolyFromText('POLYGON((-70.916 42.1002,-70.9468 42.0946,-70.9754 42.0875,-70.9749 42.0879,-70.9759 42.0897,-70.916 42.1002))')));

+-----------------------------------------------------------------------------------------------------------------------------------------------------------------+

   | ST_AsText(ST_PointOnSurface(ST_PolyFromText('POLYGON((-70.916 42.1002,-70.9468 42.0946,-70.9754 42.0875,-70.9749 42.0879,-70.9759 42.0897,-70.916 42.1002))'))) |

   +-----------------------------------------------------------------------------------------------------------------------------------------------------------------+

   | NULL                                                                                                                                                            |

   +-----------------------------------------------------------------------------------------------------------------------------------------------------------------+

Generated at Thu Feb 08 07:20:10 UTC 2024 using Jira 8.20.16#820016-sha1:9d11dbea5f4be3d4cc21f03a88dd11d8c8687422.

[MDEV-7514] GIS: PointOnSurface returns NULL instead of the point Created: 2015-01-27 Updated: 2020-11-09 Resolved: 2015-03-15