Hi,
Just compared both strings to the spec,
First string follows the WKB specification
01 endianess
06000000 MultiPolygon
02000000 Number of Polygons
01 endianess
03000000 Polygon
02000000 Two rings
04000000 Four points
...
Second string follows the Spatialite specification
http://www.gaia-gis.it/gaia-sins/BLOB-Geometry.html
01 endianess
06000000 MultiPolygon
02000000 Number of Polygons
69 Spatialite mark starting a new Geometry
03000000 Polygon
02000000 Two Rings
04000000 Four points
In spatialite geometry description, endianess is not repeated for each
component,
instead, the 69 byte appears
Probably the previous version of JTS could accomodate this because the byte
order information is generally redundant, but a more strict parser will find
a non authorized description for the Polygon as it does not start by the
byte
order.
This means that the spatialite parser which just skipped the first
bytes, then
read the following byte stream as a wkb byte array with JTS must read each
component as a Spatialite Geometry starting with 69.
Michaël
On Sun, Apr 14, 2013 at 3:39 PM, Rahkonen Jukka
<jukka.rahko...@mmmtike.fi <mailto:jukka.rahko...@mmmtike.fi>> wrote:
Hi,
I made two tests:
1) With PostGIS 2.1
select encode(ST_AsBinary(ST_GeomFromText('MULTIPOLYGON(((0 0, 10
20, 30 40, 0 0), (1 1, 2 2, 3 3, 1 1)),
((100 100, 110 110, 120 120, 100 100)))')), 'hex')
Query gives the same WKB that you used in JTS bug #3610843, that is
"0106000000020000000103000000020000000400000000000000000000000000000000000000000000000000244000000000000034400000000000003e4000000000000044400000000000000000000000000000000004000000000000000000f03f000000000000f03f0000000000000040000000000000004000000000000008400000000000000840000000000000f03f000000000000f03f01030000000100000004000000000000000000594000000000000059400000000000805b400000000000805b400000000000005e400000000000005e4000000000000059400000000000005940"
2) With Spatialite
select
GeomFromWKB(x'0106000000020000006903000000020000000400000000000000000000000000000000000000000000000000244000000000000034400000000000003E4000000000000044400000000000000000000000000000000004000000000000000000F03F000000000000F03F0000000000000040000000000000004000000000000008400000000000000840000000000000F03F000000000000F03F69030000000100000004000000000000000000594000000000000059400000000000805B400000000000805B400000000000005E400000000000005E4000000000000059400000000000005940')
Query creates a multipolygon geometry.
Jukka, these two WKB hex strings differ around the 20th character:
01060000000200000001030
01060000000200000069030
The second one is the one I retrieved from spatialite. When I try to
parse the second one with Postgis (1.5.3), I get an error:
select
ST_GeomFromWkb(decode('0106000000020000006903000000020000000400000000000000000000000000000000000000000000000000244000000000000034400000000000003E4000000000000044400000000000000000000000000000000004000000000000000000F03F000000000000F03F0000000000000040000000000000004000000000000008400000000000000840000000000000F03F000000000000F03F69030000000100000004000000000000000000594000000000000059400000000000805B400000000000805B400000000000005E400000000000005E4000000000000059400000000000005940',
'hex'));
ERROR: invalid WKB type
HINT: You must specify a valid OGC WKT geometry type such as POINT,
LINESTRING or POLYGON
I haven't manually verified the WKB, but it might be that spatialite is
generating an invalid WKB, and JTS 1.12 was more forgiving about it than
1.13 is.
-lreeder
Therefore it looks like the WKB is ok. But I do not understand that
if PostGIS gives exactly the same WKB, how it is possible that
OpenJUMP works with PostGIS but not with Spatialite through DB Query
plugin?
-Jukka Rahkonen-
------------------------------------------------------------------------------
Precog is a next-generation analytics platform capable of advanced
analytics on semi-structured data. The platform includes APIs for building
apps and a phenomenal toolset for data science. Developers can use
our toolset for easy data analysis & visualization. Get a free account!
http://www2.precog.com/precogplatform/slashdotnewsletter
_______________________________________________
Jump-pilot-devel mailing list
Jump-pilot-devel@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/jump-pilot-devel
------------------------------------------------------------------------------
Precog is a next-generation analytics platform capable of advanced
analytics on semi-structured data. The platform includes APIs for building
apps and a phenomenal toolset for data science. Developers can use
our toolset for easy data analysis & visualization. Get a free account!
http://www2.precog.com/precogplatform/slashdotnewsletter
_______________________________________________
Jump-pilot-devel mailing list
Jump-pilot-devel@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/jump-pilot-devel
