PostGIS 3D linestring validity with two different Z coordinates
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Maybe I missed something in the docs, but why is this not a valid LINESTRING Z and is a POINT Z when calling st_makeValid?
select st_isvalid(st_geomfromtext('LINESTRING Z (0 0 0,0 0 10)'));
st_isvalid
---------------
f
select st_astext(st_makevalid(st_geomfromtext('LINESTRING Z (0 0 0,0 0 10)')));
st_astext
---------------
POINT Z (0 0 0)
postgis
asked Apr 2 at 7:52
NovotmikeNovotmike
323
add a comment |
Maybe I missed something in the docs, but why is this not a valid LINESTRING Z and is a POINT Z when calling st_makeValid?
select st_isvalid(st_geomfromtext('LINESTRING Z (0 0 0,0 0 10)'));
st_isvalid
---------------
f
select st_astext(st_makevalid(st_geomfromtext('LINESTRING Z (0 0 0,0 0 10)')));
st_astext
---------------
POINT Z (0 0 0)
postgis
asked Apr 2 at 7:52
NovotmikeNovotmike
323
This looks like a bug to me.SELECT st_isvalid('LINESTRING Z(0 1 1, 0 0 10)'::geometry);returns true, whileSELECT st_isvalid('LINESTRING Z(0 0 1, 0 0 10)'::geometry);returns false.
– John Powell
Apr 2 at 9:57
Interestingly, if you call something like ST_Expand on the invalid Linestring Z, it works as expected.SELECT ST_Astext(ST_Expand('LINESTRING Z(0 0 0, 0 0 10)'::geometry, 1, 1, 1));returns POLYGON Z ((-1 -1 -1,-1 1 -1,1 1 11,1 -1 11,-1 -1 -1)). I will have a look at the source code later to see if I can find the bug, but, it looks to me that you can probably ignore the ST_Isvalid error. Also, note that ST_GeomFromText is not necessary to construct a LINESTRING Z.
– John Powell
Apr 2 at 10:01
2
I asked on the Postgis dev IRC channel and ST_IsValid only works in 2D, which explains why 0 0 0, 0 0 10 fails and 0 1 0, 0 0 10 works. sfcgal, on which the 3D extensions are based does have an IsValid function. I have been told to request an ST_3dIsValid function be hooked up to sfcgal and the docs be updated. As I suggested before, you are safe to carry on using LINESTRING Z. I will update this once I have filed the bug/request.
– John Powell
Apr 2 at 10:31
add a comment |
Maybe I missed something in the docs, but why is this not a valid LINESTRING Z and is a POINT Z when calling st_makeValid?
select st_isvalid(st_geomfromtext('LINESTRING Z (0 0 0,0 0 10)'));
st_isvalid
---------------
f
select st_astext(st_makevalid(st_geomfromtext('LINESTRING Z (0 0 0,0 0 10)')));
st_astext
---------------
POINT Z (0 0 0)
postgis
asked Apr 2 at 7:52
NovotmikeNovotmike
323
Maybe I missed something in the docs, but why is this not a valid LINESTRING Z and is a POINT Z when calling st_makeValid?
select st_isvalid(st_geomfromtext('LINESTRING Z (0 0 0,0 0 10)'));
st_isvalid
---------------
f
select st_astext(st_makevalid(st_geomfromtext('LINESTRING Z (0 0 0,0 0 10)')));
st_astext
---------------
POINT Z (0 0 0)
postgis
postgis
asked Apr 2 at 7:52
NovotmikeNovotmike
323
asked Apr 2 at 7:52
NovotmikeNovotmike
323
asked Apr 2 at 7:52
NovotmikeNovotmike
323
asked Apr 2 at 7:52
NovotmikeNovotmike
323
asked Apr 2 at 7:52
NovotmikeNovotmike
323
323
This looks like a bug to me.SELECT st_isvalid('LINESTRING Z(0 1 1, 0 0 10)'::geometry);returns true, whileSELECT st_isvalid('LINESTRING Z(0 0 1, 0 0 10)'::geometry);returns false.
– John Powell
Apr 2 at 9:57
Interestingly, if you call something like ST_Expand on the invalid Linestring Z, it works as expected.SELECT ST_Astext(ST_Expand('LINESTRING Z(0 0 0, 0 0 10)'::geometry, 1, 1, 1));returns POLYGON Z ((-1 -1 -1,-1 1 -1,1 1 11,1 -1 11,-1 -1 -1)). I will have a look at the source code later to see if I can find the bug, but, it looks to me that you can probably ignore the ST_Isvalid error. Also, note that ST_GeomFromText is not necessary to construct a LINESTRING Z.
– John Powell
Apr 2 at 10:01
2
I asked on the Postgis dev IRC channel and ST_IsValid only works in 2D, which explains why 0 0 0, 0 0 10 fails and 0 1 0, 0 0 10 works. sfcgal, on which the 3D extensions are based does have an IsValid function. I have been told to request an ST_3dIsValid function be hooked up to sfcgal and the docs be updated. As I suggested before, you are safe to carry on using LINESTRING Z. I will update this once I have filed the bug/request.
– John Powell
Apr 2 at 10:31
add a comment |
This looks like a bug to me.SELECT st_isvalid('LINESTRING Z(0 1 1, 0 0 10)'::geometry);returns true, whileSELECT st_isvalid('LINESTRING Z(0 0 1, 0 0 10)'::geometry);returns false.
– John Powell
Apr 2 at 9:57
Interestingly, if you call something like ST_Expand on the invalid Linestring Z, it works as expected.SELECT ST_Astext(ST_Expand('LINESTRING Z(0 0 0, 0 0 10)'::geometry, 1, 1, 1));returns POLYGON Z ((-1 -1 -1,-1 1 -1,1 1 11,1 -1 11,-1 -1 -1)). I will have a look at the source code later to see if I can find the bug, but, it looks to me that you can probably ignore the ST_Isvalid error. Also, note that ST_GeomFromText is not necessary to construct a LINESTRING Z.
– John Powell
Apr 2 at 10:01
2
I asked on the Postgis dev IRC channel and ST_IsValid only works in 2D, which explains why 0 0 0, 0 0 10 fails and 0 1 0, 0 0 10 works. sfcgal, on which the 3D extensions are based does have an IsValid function. I have been told to request an ST_3dIsValid function be hooked up to sfcgal and the docs be updated. As I suggested before, you are safe to carry on using LINESTRING Z. I will update this once I have filed the bug/request.
– John Powell
Apr 2 at 10:31
This looks like a bug to me.
SELECT st_isvalid('LINESTRING Z(0 1 1, 0 0 10)'::geometry); returns true, while SELECT st_isvalid('LINESTRING Z(0 0 1, 0 0 10)'::geometry); returns false.– John Powell
Apr 2 at 9:57
This looks like a bug to me.
SELECT st_isvalid('LINESTRING Z(0 1 1, 0 0 10)'::geometry); returns true, while SELECT st_isvalid('LINESTRING Z(0 0 1, 0 0 10)'::geometry); returns false.– John Powell
Apr 2 at 9:57
Interestingly, if you call something like ST_Expand on the invalid Linestring Z, it works as expected.
SELECT ST_Astext(ST_Expand('LINESTRING Z(0 0 0, 0 0 10)'::geometry, 1, 1, 1)); returns POLYGON Z ((-1 -1 -1,-1 1 -1,1 1 11,1 -1 11,-1 -1 -1)). I will have a look at the source code later to see if I can find the bug, but, it looks to me that you can probably ignore the ST_Isvalid error. Also, note that ST_GeomFromText is not necessary to construct a LINESTRING Z.– John Powell
Apr 2 at 10:01
Interestingly, if you call something like ST_Expand on the invalid Linestring Z, it works as expected.
SELECT ST_Astext(ST_Expand('LINESTRING Z(0 0 0, 0 0 10)'::geometry, 1, 1, 1)); returns POLYGON Z ((-1 -1 -1,-1 1 -1,1 1 11,1 -1 11,-1 -1 -1)). I will have a look at the source code later to see if I can find the bug, but, it looks to me that you can probably ignore the ST_Isvalid error. Also, note that ST_GeomFromText is not necessary to construct a LINESTRING Z.– John Powell
Apr 2 at 10:01
2
2
I asked on the Postgis dev IRC channel and ST_IsValid only works in 2D, which explains why 0 0 0, 0 0 10 fails and 0 1 0, 0 0 10 works. sfcgal, on which the 3D extensions are based does have an IsValid function. I have been told to request an ST_3dIsValid function be hooked up to sfcgal and the docs be updated. As I suggested before, you are safe to carry on using LINESTRING Z. I will update this once I have filed the bug/request.
– John Powell
Apr 2 at 10:31
I asked on the Postgis dev IRC channel and ST_IsValid only works in 2D, which explains why 0 0 0, 0 0 10 fails and 0 1 0, 0 0 10 works. sfcgal, on which the 3D extensions are based does have an IsValid function. I have been told to request an ST_3dIsValid function be hooked up to sfcgal and the docs be updated. As I suggested before, you are safe to carry on using LINESTRING Z. I will update this once I have filed the bug/request.
– John Powell
Apr 2 at 10:31
add a comment |
1 Answer
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This is expected behaviour as the existing Postgis/GEOS codebase only checks 2D coordinates, ie, it ignores the z coordinate.
If you run,
SELECT ST_IsValid('LINESTRING Z(0 1 0, 0 0 10)'::geometry);
it returns true, as you now have a valid 2D LINESTRING.
I was advised on the Postgis developers irc channel to file a feature request, to request a ST_3dIsValid function that would hook into the existing sfcgal IsValid function and, also, a request to update the docs for ST_IsValid.
Note, for now, you can ignore ST_IsValid with LINESTRING Z, as the underlying functionality appears to be correct, eg,
SELECT ST_Astext(ST_Expand('LINESTRING Z(0 0 0, 0 0 10)'::geometry, 1, 1, 1));
returns:
POLYGON Z ((-1 -1 -1,-1 1 -1,1 1 11,1 -1 11,-1 -1 -1))
answered Apr 2 at 11:00
John PowellJohn Powell
10.9k43050
add a comment |
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1 Answer
1
active
oldest
votes
1 Answer
1
active
oldest
votes
active
oldest
votes
active
oldest
votes
This is expected behaviour as the existing Postgis/GEOS codebase only checks 2D coordinates, ie, it ignores the z coordinate.
If you run,
SELECT ST_IsValid('LINESTRING Z(0 1 0, 0 0 10)'::geometry);
it returns true, as you now have a valid 2D LINESTRING.
I was advised on the Postgis developers irc channel to file a feature request, to request a ST_3dIsValid function that would hook into the existing sfcgal IsValid function and, also, a request to update the docs for ST_IsValid.
Note, for now, you can ignore ST_IsValid with LINESTRING Z, as the underlying functionality appears to be correct, eg,
SELECT ST_Astext(ST_Expand('LINESTRING Z(0 0 0, 0 0 10)'::geometry, 1, 1, 1));
returns:
POLYGON Z ((-1 -1 -1,-1 1 -1,1 1 11,1 -1 11,-1 -1 -1))
answered Apr 2 at 11:00
John PowellJohn Powell
10.9k43050
add a comment |
This is expected behaviour as the existing Postgis/GEOS codebase only checks 2D coordinates, ie, it ignores the z coordinate.
If you run,
SELECT ST_IsValid('LINESTRING Z(0 1 0, 0 0 10)'::geometry);
it returns true, as you now have a valid 2D LINESTRING.
I was advised on the Postgis developers irc channel to file a feature request, to request a ST_3dIsValid function that would hook into the existing sfcgal IsValid function and, also, a request to update the docs for ST_IsValid.
Note, for now, you can ignore ST_IsValid with LINESTRING Z, as the underlying functionality appears to be correct, eg,
SELECT ST_Astext(ST_Expand('LINESTRING Z(0 0 0, 0 0 10)'::geometry, 1, 1, 1));
returns:
POLYGON Z ((-1 -1 -1,-1 1 -1,1 1 11,1 -1 11,-1 -1 -1))
answered Apr 2 at 11:00
John PowellJohn Powell
10.9k43050
add a comment |
This is expected behaviour as the existing Postgis/GEOS codebase only checks 2D coordinates, ie, it ignores the z coordinate.
If you run,
SELECT ST_IsValid('LINESTRING Z(0 1 0, 0 0 10)'::geometry);
it returns true, as you now have a valid 2D LINESTRING.
I was advised on the Postgis developers irc channel to file a feature request, to request a ST_3dIsValid function that would hook into the existing sfcgal IsValid function and, also, a request to update the docs for ST_IsValid.
Note, for now, you can ignore ST_IsValid with LINESTRING Z, as the underlying functionality appears to be correct, eg,
SELECT ST_Astext(ST_Expand('LINESTRING Z(0 0 0, 0 0 10)'::geometry, 1, 1, 1));
returns:
POLYGON Z ((-1 -1 -1,-1 1 -1,1 1 11,1 -1 11,-1 -1 -1))
answered Apr 2 at 11:00
John PowellJohn Powell
10.9k43050
This is expected behaviour as the existing Postgis/GEOS codebase only checks 2D coordinates, ie, it ignores the z coordinate.
If you run,
SELECT ST_IsValid('LINESTRING Z(0 1 0, 0 0 10)'::geometry);
it returns true, as you now have a valid 2D LINESTRING.
I was advised on the Postgis developers irc channel to file a feature request, to request a ST_3dIsValid function that would hook into the existing sfcgal IsValid function and, also, a request to update the docs for ST_IsValid.
Note, for now, you can ignore ST_IsValid with LINESTRING Z, as the underlying functionality appears to be correct, eg,
SELECT ST_Astext(ST_Expand('LINESTRING Z(0 0 0, 0 0 10)'::geometry, 1, 1, 1));
returns:
POLYGON Z ((-1 -1 -1,-1 1 -1,1 1 11,1 -1 11,-1 -1 -1))
answered Apr 2 at 11:00
John PowellJohn Powell
10.9k43050
answered Apr 2 at 11:00
John PowellJohn Powell
10.9k43050
answered Apr 2 at 11:00
John PowellJohn Powell
10.9k43050
answered Apr 2 at 11:00
John PowellJohn Powell
10.9k43050
10.9k43050
add a comment |
add a comment |
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This looks like a bug to me.
SELECT st_isvalid('LINESTRING Z(0 1 1, 0 0 10)'::geometry);returns true, whileSELECT st_isvalid('LINESTRING Z(0 0 1, 0 0 10)'::geometry);returns false.– John Powell
Apr 2 at 9:57
Interestingly, if you call something like ST_Expand on the invalid Linestring Z, it works as expected.
SELECT ST_Astext(ST_Expand('LINESTRING Z(0 0 0, 0 0 10)'::geometry, 1, 1, 1));returns POLYGON Z ((-1 -1 -1,-1 1 -1,1 1 11,1 -1 11,-1 -1 -1)). I will have a look at the source code later to see if I can find the bug, but, it looks to me that you can probably ignore the ST_Isvalid error. Also, note that ST_GeomFromText is not necessary to construct a LINESTRING Z.– John Powell
Apr 2 at 10:01
2
I asked on the Postgis dev IRC channel and ST_IsValid only works in 2D, which explains why 0 0 0, 0 0 10 fails and 0 1 0, 0 0 10 works. sfcgal, on which the 3D extensions are based does have an IsValid function. I have been told to request an ST_3dIsValid function be hooked up to sfcgal and the docs be updated. As I suggested before, you are safe to carry on using LINESTRING Z. I will update this once I have filed the bug/request.
– John Powell
Apr 2 at 10:31