Re: [Qgis-user] Pseudo Mercator(OSM) @ EPSG:4326 bug?

[Idan Miara]

Ok, Thanks for your detailed explanation!

On 5 Mar 2018 15:41, "Kristian Evers" <kr...@sdfe.dk> wrote:

It would be nice if the Web Mercator was never introduced to the EPSG
register,
but nothing we can do about that now. The problem has indeed seeped into
PROJ by mistake (will be fixed with 5.0.1). Unfortunately the internal
architecture
in PROJ makes it quite hard to handle both the Web Mercator and treat other
(not so common) transformations with a shift in ellipsoid correctly. Luckily
this is only a problem in the old API. The new API introduced in 5.0.0 is
more
flexible and can handle both correctly. It will be a while before that is
easily
available for downstream projects such as QGIS.

/Kristian


-Oprindelig meddelelse-
Fra: Qgis-user [mailto:qgis-user-boun...@lists.osgeo.org] På vegne af
Benjamin Ducke
Sendt: 5. marts 2018 11:58
Til: qgis-user <qgis-user@lists.osgeo.org>
Emne: Re: [Qgis-user] Pseudo Mercator(OSM) @ EPSG:4326 bug?

It all boils down to the same fundamental issue:
Google Earth/Maps, etc. _pretend_ that their data
is WGS84, but they do not implement the WGS84
ellipsoid. So when tools like PROJ attempt to
do the _technically correct_ thing and perform
a datum transformation WGS84 <-> Web Mercator, then
data ends up in the wrong place. If they don't,
then people get confused, because the two systems
are different. This confusion is now seeping into
PROJ and from there into higher-level apps like
QGIS. I wish EPSG had never included Web Mercator into
its database. Then we could just ignore all of this,
use EPSG:4326 and live in blissful ignorance.

On 05/03/18 11:42, Idan Miara wrote:
> Thanks for you reply,
> Since the problem exist also in 2.18 I don't think it is related with
> PROJ 5.0, Right?
>
> On 5 Mar 2018 12:39, "Kristian Evers" <kr...@sdfe.dk
> <mailto:kr...@sdfe.dk>> wrote:
>
> If you are using PROJ 5.0.0 it is likely to be caused by this known
> issue:
>
> https://github.com/OSGeo/proj.4/issues/834
> <https://github.com/OSGeo/proj.4/issues/834>
>
> /Kristian
>
> -Oprindelig meddelelse-
> Fra: Qgis-user [mailto:qgis-user-boun...@lists.osgeo.org
> <mailto:qgis-user-boun...@lists.osgeo.org>] På vegne af Benjamin Ducke
>     Sendt: 5. marts 2018 10:18
> Til: qgis-user@lists.osgeo.org <mailto:qgis-user@lists.osgeo.org>
> Emne: Re: [Qgis-user] Pseudo Mercator(OSM) @ EPSG:4326 bug?
>
> Could it be this:
>
> http://proj4.org/faq.html#changing-ellipsoid-why-can-t-
i-convert-from-wgs84-to-google-earth-virtual-globe-mercator
> <http://proj4.org/faq.html#changing-ellipsoid-why-can-t-
i-convert-from-wgs84-to-google-earth-virtual-globe-mercator>
>
> ?
>
> The further you get from the equator, the more
> obvious the discrepancy on the Y axis.
>
> Best,
>
> Ben
>
> On 05/03/18 09:38, Idan Miara wrote:
> > Hi,
> >
> > I might have found a bug related to transformation of layer CRS
> > from EPSG:3857 (Pseudo Mercator) to EPSG:4325 (WGS84 Geo).
> > I'm attaching a few images to demonstrate the issue.
> >
> > Steps to reproduce:
> > I've load OSM in QGIS 2.18.16 (or 3.0,same results)
> > via Tile Server (XYZ):
> > https://a.tile.openstreetmap.org/{z}/{x}/{y}.png
> <https://a.tile.openstreetmap.org/{z}/{x}/{y}.png>
> > <https://a.tile.openstreetmap.org/%7Bz%7D/%7Bx%7D/%7By%7D.png
> <https://a.tile.openstreetmap.org/%7Bz%7D/%7Bx%7D/%7By%7D.png>>
> >
> > Then set the CRS to EPSG:4326 (WGS84 Geo)
> >
> > I've also loaded a global bounds vector layer (EPSG:4326)
> >
> > In scale 1:100,000,000 it seems that the Pseudo Mercator
> transformation
> > to 4326 is flawed, as the OSM and the vectors are not aligned.
> > In scale 1:50,000,000 it seems OK when the extent is the middle of
the
> > map, but if I pan to the south/north it seems distorted again.
> >
> > If I set the project CRS to EPSG:3857 (Pseudo Mercator) as the CRS
of
> > the OSM tiles, so the vector layer would be transformed instead,
then
> > they do align in all scales (picture with the blue vector layer).
> >
> > It doesn't look like a problem of precision of the transformation
from
> > 3857 to 4325 because it's way off.
> > Is that a bug or am I missing something here?
> >
> > Kind regards,
> > Idan.
> >
> >
> >
> > ___
> > Qgis-user mailing list
> > Qgis-user@lists.osgeo.org <mailto:Qgis-us

Re: [Qgis-user] Pseudo Mercator(OSM) @ EPSG:4326 bug?

[Kristian Evers]

It would be nice if the Web Mercator was never introduced to the EPSG register,
but nothing we can do about that now. The problem has indeed seeped into
PROJ by mistake (will be fixed with 5.0.1). Unfortunately the internal 
architecture
in PROJ makes it quite hard to handle both the Web Mercator and treat other
(not so common) transformations with a shift in ellipsoid correctly. Luckily
this is only a problem in the old API. The new API introduced in 5.0.0 is more
flexible and can handle both correctly. It will be a while before that is easily
available for downstream projects such as QGIS.

/Kristian


-Oprindelig meddelelse-
Fra: Qgis-user [mailto:qgis-user-boun...@lists.osgeo.org] På vegne af Benjamin 
Ducke
Sendt: 5. marts 2018 11:58
Til: qgis-user <qgis-user@lists.osgeo.org>
Emne: Re: [Qgis-user] Pseudo Mercator(OSM) @ EPSG:4326 bug?

It all boils down to the same fundamental issue:
Google Earth/Maps, etc. _pretend_ that their data
is WGS84, but they do not implement the WGS84
ellipsoid. So when tools like PROJ attempt to
do the _technically correct_ thing and perform
a datum transformation WGS84 <-> Web Mercator, then
data ends up in the wrong place. If they don't,
then people get confused, because the two systems
are different. This confusion is now seeping into
PROJ and from there into higher-level apps like
QGIS. I wish EPSG had never included Web Mercator into
its database. Then we could just ignore all of this,
use EPSG:4326 and live in blissful ignorance.

On 05/03/18 11:42, Idan Miara wrote:
> Thanks for you reply,
> Since the problem exist also in 2.18 I don't think it is related with
> PROJ 5.0, Right? 
> 
> On 5 Mar 2018 12:39, "Kristian Evers" <kr...@sdfe.dk
> <mailto:kr...@sdfe.dk>> wrote:
> 
> If you are using PROJ 5.0.0 it is likely to be caused by this known
> issue:
> 
> https://github.com/OSGeo/proj.4/issues/834
> <https://github.com/OSGeo/proj.4/issues/834>
> 
> /Kristian
> 
> -Oprindelig meddelelse-
> Fra: Qgis-user [mailto:qgis-user-boun...@lists.osgeo.org
> <mailto:qgis-user-boun...@lists.osgeo.org>] På vegne af Benjamin Ducke
> Sendt: 5. marts 2018 10:18
> Til: qgis-user@lists.osgeo.org <mailto:qgis-user@lists.osgeo.org>
> Emne: Re: [Qgis-user] Pseudo Mercator(OSM) @ EPSG:4326 bug?
> 
> Could it be this:
> 
> 
> http://proj4.org/faq.html#changing-ellipsoid-why-can-t-i-convert-from-wgs84-to-google-earth-virtual-globe-mercator
> 
> <http://proj4.org/faq.html#changing-ellipsoid-why-can-t-i-convert-from-wgs84-to-google-earth-virtual-globe-mercator>
> 
> ?
> 
> The further you get from the equator, the more
> obvious the discrepancy on the Y axis.
> 
> Best,
> 
> Ben
> 
> On 05/03/18 09:38, Idan Miara wrote:
> > Hi,
> >
> > I might have found a bug related to transformation of layer CRS
> > from EPSG:3857 (Pseudo Mercator) to EPSG:4325 (WGS84 Geo).
> > I'm attaching a few images to demonstrate the issue. 
> >
> > Steps to reproduce:
> > I've load OSM in QGIS 2.18.16 (or 3.0,same results)
> > via Tile Server (XYZ):
> > https://a.tile.openstreetmap.org/{z}/{x}/{y}.png
> <https://a.tile.openstreetmap.org/{z}/{x}/{y}.png>
> > <https://a.tile.openstreetmap.org/%7Bz%7D/%7Bx%7D/%7By%7D.png
> <https://a.tile.openstreetmap.org/%7Bz%7D/%7Bx%7D/%7By%7D.png>>
> >
> > Then set the CRS to EPSG:4326 (WGS84 Geo)
> >
> > I've also loaded a global bounds vector layer (EPSG:4326)
> >
> > In scale 1:100,000,000 it seems that the Pseudo Mercator
> transformation
> > to 4326 is flawed, as the OSM and the vectors are not aligned.
> > In scale 1:50,000,000 it seems OK when the extent is the middle of the
> > map, but if I pan to the south/north it seems distorted again.
> >
> > If I set the project CRS to EPSG:3857 (Pseudo Mercator) as the CRS of
> > the OSM tiles, so the vector layer would be transformed instead, then
> > they do align in all scales (picture with the blue vector layer).
> >
> > It doesn't look like a problem of precision of the transformation from
> > 3857 to 4325 because it's way off. 
> > Is that a bug or am I missing something here?
> >
> > Kind regards,
> > Idan.
> >
> >
> >
> > ___
> > Qgis-user mailing list
> > Qgis-user@lists.osgeo.org <mailto:Qgis-user@lists.osgeo.org>
> > List info: https://lists.osgeo.org/mailman/listinfo/qgis-user
> <htt

Re: [Qgis-user] Pseudo Mercator(OSM) @ EPSG:4326 bug?

[Idan Miara]

It does, but the problem is when I set the project CRS to 4326, so the
tiles are projected from 3857 to 4326. The vector layer is not projected.

On 5 Mar 2018 13:23, "Andre Joost"  wrote:

Am 05.03.18 um 09:38 schrieb Idan Miara:

  Hi,
>
> I might have found a bug related to transformation of layer CRS from
> EPSG:3857
> (Pseudo Mercator) to EPSG:4325 (WGS84 Geo).
> I'm attaching a few images to demonstrate the issue.
>
> Steps to reproduce:
> I've load OSM in QGIS 2.18.16 (or 3.0,same results)
> via Tile Server (XYZ):
> https://a.tile.openstreetmap.org/{z}/{x}/{y}.png
>
> Then set the CRS to EPSG:4326 (WGS84 Geo)
>
> I've also loaded a global bounds vector layer (EPSG:4326)
>
>
Does the vector layer contain the north or south pole? EPSG:3857 does not
like that (it would be in infinity). The same might happen if you request
tiles beyond 85°N/S.

HTH,
Andre Joost



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Re: [Qgis-user] Pseudo Mercator(OSM) @ EPSG:4326 bug?

[Andre Joost]

Am 05.03.18 um 09:38 schrieb Idan Miara:

  Hi,

I might have found a bug related to transformation of layer CRS from EPSG:3857
(Pseudo Mercator) to EPSG:4325 (WGS84 Geo).
I'm attaching a few images to demonstrate the issue.

Steps to reproduce:
I've load OSM in QGIS 2.18.16 (or 3.0,same results)
via Tile Server (XYZ):
https://a.tile.openstreetmap.org/{z}/{x}/{y}.png

Then set the CRS to EPSG:4326 (WGS84 Geo)

I've also loaded a global bounds vector layer (EPSG:4326)



Does the vector layer contain the north or south pole? EPSG:3857 does 
not like that (it would be in infinity). The same might happen if you 
request tiles beyond 85°N/S.


HTH,
Andre Joost


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Re: [Qgis-user] Pseudo Mercator(OSM) @ EPSG:4326 bug?

[Benjamin Ducke]

On 05/03/18 12:12, Idan Miara wrote:
> Forgive me for not understanding the fine details of the flaws in Web
> Mercator.
> Fast forward back the reality where many tile servers provide tiles in
> 3857, and 4326 to 3857 seems OK, how can I debug this issue in the
> inverse transformation?

I don't think you can. The "fix" would be to force QGIS
to treat all data as WGS:4326 (see again the link I
provided in my first answer).

That seems to be the reality of this mess.

Best,

Ben

> 
> I guess I could export the OSM map in 3857 to TIF to rule out the
> possibility that the problem in the tile server, so that I can be sure
> that QGIS is transforming the raster?
> 
> 
> On 5 Mar 2018 12:57, "Benjamin Ducke" <bendu...@fastmail.fm
> <mailto:bendu...@fastmail.fm>> wrote:
> 
> It all boils down to the same fundamental issue:
> Google Earth/Maps, etc. _pretend_ that their data
> is WGS84, but they do not implement the WGS84
> ellipsoid. So when tools like PROJ attempt to
> do the _technically correct_ thing and perform
> a datum transformation WGS84 <-> Web Mercator, then
> data ends up in the wrong place. If they don't,
> then people get confused, because the two systems
> are different. This confusion is now seeping into
> PROJ and from there into higher-level apps like
> QGIS. I wish EPSG had never included Web Mercator into
> its database. Then we could just ignore all of this,
> use EPSG:4326 and live in blissful ignorance.
> 
> On 05/03/18 11:42, Idan Miara wrote:
> > Thanks for you reply,
> > Since the problem exist also in 2.18 I don't think it is related with
> > PROJ 5.0, Right? 
> >
> > On 5 Mar 2018 12:39, "Kristian Evers" <kr...@sdfe.dk
> <mailto:kr...@sdfe.dk>
> > <mailto:kr...@sdfe.dk <mailto:kr...@sdfe.dk>>> wrote:
> >
> >     If you are using PROJ 5.0.0 it is likely to be caused by this
> known
> >     issue:
> >
> >     https://github.com/OSGeo/proj.4/issues/834
> <https://github.com/OSGeo/proj.4/issues/834>
> >     <https://github.com/OSGeo/proj.4/issues/834
> <https://github.com/OSGeo/proj.4/issues/834>>
> >
> >     /Kristian
> >
> >     -Oprindelig meddelelse-
> >     Fra: Qgis-user [mailto:qgis-user-boun...@lists.osgeo.org
> <mailto:qgis-user-boun...@lists.osgeo.org>
> >     <mailto:qgis-user-boun...@lists.osgeo.org
> <mailto:qgis-user-boun...@lists.osgeo.org>>] På vegne af Benjamin Ducke
> >     Sendt: 5. marts 2018 10:18
> >     Til: qgis-user@lists.osgeo.org
> <mailto:qgis-user@lists.osgeo.org> <mailto:qgis-user@lists.osgeo.org
> <mailto:qgis-user@lists.osgeo.org>>
> >     Emne: Re: [Qgis-user] Pseudo Mercator(OSM) @ EPSG:4326 bug?
> >
> >     Could it be this:
> >
> >   
>  
> http://proj4.org/faq.html#changing-ellipsoid-why-can-t-i-convert-from-wgs84-to-google-earth-virtual-globe-mercator
> 
> <http://proj4.org/faq.html#changing-ellipsoid-why-can-t-i-convert-from-wgs84-to-google-earth-virtual-globe-mercator>
> >   
>  
> <http://proj4.org/faq.html#changing-ellipsoid-why-can-t-i-convert-from-wgs84-to-google-earth-virtual-globe-mercator
> 
> <http://proj4.org/faq.html#changing-ellipsoid-why-can-t-i-convert-from-wgs84-to-google-earth-virtual-globe-mercator>>
> >
> >     ?
> >
> >     The further you get from the equator, the more
> >     obvious the discrepancy on the Y axis.
> >
> >     Best,
> >
> >     Ben
> >
> >     On 05/03/18 09:38, Idan Miara wrote:
> >     > Hi,
> >     >
> >     > I might have found a bug related to transformation of layer CRS
> >     > from EPSG:3857 (Pseudo Mercator) to EPSG:4325 (WGS84 Geo).
> >     > I'm attaching a few images to demonstrate the issue. 
> >     >
> >     > Steps to reproduce:
> >     > I've load OSM in QGIS 2.18.16 (or 3.0,same results)
> >     > via Tile Server (XYZ):
> >     > https://a.tile.openstreetmap.org/{z}/{x}/{y}.png
> <https://a.tile.openstreetmap.org/{z}/{x}/{y}.png>
> >     <https://a.tile.openstreetmap.org/{z}/{x}/{y}.png
> <https://a.tile.openstreetmap.org/{z}/{x}/{y}.png>>
> >     >
> <https://a.tile.openstreetmap.org/%7Bz%7D/%7Bx%7D/%7By%7D.png
> <https://a.tile.openstreetmap

Re: [Qgis-user] Pseudo Mercator(OSM) @ EPSG:4326 bug?

[Idan Miara]

Forgive me for not understanding the fine details of the flaws in Web
Mercator.
Fast forward back the reality where many tile servers provide tiles in
3857, and 4326 to 3857 seems OK, how can I debug this issue in the inverse
transformation?

I guess I could export the OSM map in 3857 to TIF to rule out the
possibility that the problem in the tile server, so that I can be sure that
QGIS is transforming the raster?


On 5 Mar 2018 12:57, "Benjamin Ducke" <bendu...@fastmail.fm> wrote:

It all boils down to the same fundamental issue:
Google Earth/Maps, etc. _pretend_ that their data
is WGS84, but they do not implement the WGS84
ellipsoid. So when tools like PROJ attempt to
do the _technically correct_ thing and perform
a datum transformation WGS84 <-> Web Mercator, then
data ends up in the wrong place. If they don't,
then people get confused, because the two systems
are different. This confusion is now seeping into
PROJ and from there into higher-level apps like
QGIS. I wish EPSG had never included Web Mercator into
its database. Then we could just ignore all of this,
use EPSG:4326 and live in blissful ignorance.

On 05/03/18 11:42, Idan Miara wrote:
> Thanks for you reply,
> Since the problem exist also in 2.18 I don't think it is related with
> PROJ 5.0, Right?
>
> On 5 Mar 2018 12:39, "Kristian Evers" <kr...@sdfe.dk
> <mailto:kr...@sdfe.dk>> wrote:
>
> If you are using PROJ 5.0.0 it is likely to be caused by this known
> issue:
>
> https://github.com/OSGeo/proj.4/issues/834
> <https://github.com/OSGeo/proj.4/issues/834>
>
> /Kristian
>
> -Oprindelig meddelelse-
> Fra: Qgis-user [mailto:qgis-user-boun...@lists.osgeo.org
> <mailto:qgis-user-boun...@lists.osgeo.org>] På vegne af Benjamin Ducke
> Sendt: 5. marts 2018 10:18
>     Til: qgis-user@lists.osgeo.org <mailto:qgis-user@lists.osgeo.org>
> Emne: Re: [Qgis-user] Pseudo Mercator(OSM) @ EPSG:4326 bug?
>
> Could it be this:
>
> http://proj4.org/faq.html#changing-ellipsoid-why-can-t-
i-convert-from-wgs84-to-google-earth-virtual-globe-mercator
> <http://proj4.org/faq.html#changing-ellipsoid-why-can-t-
i-convert-from-wgs84-to-google-earth-virtual-globe-mercator>
>
> ?
>
> The further you get from the equator, the more
> obvious the discrepancy on the Y axis.
>
> Best,
>
> Ben
>
> On 05/03/18 09:38, Idan Miara wrote:
> > Hi,
> >
> > I might have found a bug related to transformation of layer CRS
> > from EPSG:3857 (Pseudo Mercator) to EPSG:4325 (WGS84 Geo).
> > I'm attaching a few images to demonstrate the issue.
> >
> > Steps to reproduce:
> > I've load OSM in QGIS 2.18.16 (or 3.0,same results)
> > via Tile Server (XYZ):
> > https://a.tile.openstreetmap.org/{z}/{x}/{y}.png
> <https://a.tile.openstreetmap.org/{z}/{x}/{y}.png>
> > <https://a.tile.openstreetmap.org/%7Bz%7D/%7Bx%7D/%7By%7D.png
> <https://a.tile.openstreetmap.org/%7Bz%7D/%7Bx%7D/%7By%7D.png>>
> >
> > Then set the CRS to EPSG:4326 (WGS84 Geo)
> >
> > I've also loaded a global bounds vector layer (EPSG:4326)
> >
> > In scale 1:100,000,000 it seems that the Pseudo Mercator
> transformation
> > to 4326 is flawed, as the OSM and the vectors are not aligned.
> > In scale 1:50,000,000 it seems OK when the extent is the middle of
the
> > map, but if I pan to the south/north it seems distorted again.
> >
> > If I set the project CRS to EPSG:3857 (Pseudo Mercator) as the CRS
of
> > the OSM tiles, so the vector layer would be transformed instead,
then
> > they do align in all scales (picture with the blue vector layer).
> >
> > It doesn't look like a problem of precision of the transformation
from
> > 3857 to 4325 because it's way off.
> > Is that a bug or am I missing something here?
> >
> > Kind regards,
> > Idan.
> >
> >
> >
> > ___
> > Qgis-user mailing list
> > Qgis-user@lists.osgeo.org <mailto:Qgis-user@lists.osgeo.org>
> > List info: https://lists.osgeo.org/mailman/listinfo/qgis-user
> <https://lists.osgeo.org/mailman/listinfo/qgis-user>
> > Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-user
> <https://lists.osgeo.org/mailman/listinfo/qgis-user>
> >
>
>
>
> --
> Dr. Benjamin Ducke
> Deutsches Archäologisches Institut (DAI)
> Zentrale Berlin, IT-Referat
> * Projekt "Stun

Re: [Qgis-user] Pseudo Mercator(OSM) @ EPSG:4326 bug?

[b.j.kobben]

You can use a browser to request data from the tileserver, but let me assure 
you that the OSM tileserver you are using 
(https://a.tile.openstreetmap.org/{z}/{x}/{y}.png)
 for sure only supports 3857 (or its quasi-alias 900913), so it’s a lots cause 
to expect it to provide 4326 tiles. Better work the other way around: have your 
map/project in 3857 and reproject the 4326 data to that.


--
Barend Köbben

On 05/03/2018, 11:53, "Idan Miara" > 
wrote:

https://a.tile.openstreetmap.org/{z}/{x}/{y}.png
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Re: [Qgis-user] Pseudo Mercator(OSM) @ EPSG:4326 bug?

[Benjamin Ducke]

It all boils down to the same fundamental issue:
Google Earth/Maps, etc. _pretend_ that their data
is WGS84, but they do not implement the WGS84
ellipsoid. So when tools like PROJ attempt to
do the _technically correct_ thing and perform
a datum transformation WGS84 <-> Web Mercator, then
data ends up in the wrong place. If they don't,
then people get confused, because the two systems
are different. This confusion is now seeping into
PROJ and from there into higher-level apps like
QGIS. I wish EPSG had never included Web Mercator into
its database. Then we could just ignore all of this,
use EPSG:4326 and live in blissful ignorance.

On 05/03/18 11:42, Idan Miara wrote:
> Thanks for you reply,
> Since the problem exist also in 2.18 I don't think it is related with
> PROJ 5.0, Right? 
> 
> On 5 Mar 2018 12:39, "Kristian Evers" <kr...@sdfe.dk
> <mailto:kr...@sdfe.dk>> wrote:
> 
> If you are using PROJ 5.0.0 it is likely to be caused by this known
> issue:
> 
> https://github.com/OSGeo/proj.4/issues/834
> <https://github.com/OSGeo/proj.4/issues/834>
> 
> /Kristian
> 
> -Oprindelig meddelelse-
> Fra: Qgis-user [mailto:qgis-user-boun...@lists.osgeo.org
> <mailto:qgis-user-boun...@lists.osgeo.org>] På vegne af Benjamin Ducke
> Sendt: 5. marts 2018 10:18
> Til: qgis-user@lists.osgeo.org <mailto:qgis-user@lists.osgeo.org>
> Emne: Re: [Qgis-user] Pseudo Mercator(OSM) @ EPSG:4326 bug?
> 
> Could it be this:
> 
> 
> http://proj4.org/faq.html#changing-ellipsoid-why-can-t-i-convert-from-wgs84-to-google-earth-virtual-globe-mercator
> 
> <http://proj4.org/faq.html#changing-ellipsoid-why-can-t-i-convert-from-wgs84-to-google-earth-virtual-globe-mercator>
> 
> ?
> 
> The further you get from the equator, the more
> obvious the discrepancy on the Y axis.
> 
> Best,
> 
> Ben
> 
> On 05/03/18 09:38, Idan Miara wrote:
> > Hi,
> >
> > I might have found a bug related to transformation of layer CRS
> > from EPSG:3857 (Pseudo Mercator) to EPSG:4325 (WGS84 Geo).
> > I'm attaching a few images to demonstrate the issue. 
> >
> > Steps to reproduce:
> > I've load OSM in QGIS 2.18.16 (or 3.0,same results)
> > via Tile Server (XYZ):
> > https://a.tile.openstreetmap.org/{z}/{x}/{y}.png
> <https://a.tile.openstreetmap.org/{z}/{x}/{y}.png>
> > <https://a.tile.openstreetmap.org/%7Bz%7D/%7Bx%7D/%7By%7D.png
> <https://a.tile.openstreetmap.org/%7Bz%7D/%7Bx%7D/%7By%7D.png>>
> >
> > Then set the CRS to EPSG:4326 (WGS84 Geo)
> >
> > I've also loaded a global bounds vector layer (EPSG:4326)
> >
> > In scale 1:100,000,000 it seems that the Pseudo Mercator
> transformation
> > to 4326 is flawed, as the OSM and the vectors are not aligned.
> > In scale 1:50,000,000 it seems OK when the extent is the middle of the
> > map, but if I pan to the south/north it seems distorted again.
> >
> > If I set the project CRS to EPSG:3857 (Pseudo Mercator) as the CRS of
> > the OSM tiles, so the vector layer would be transformed instead, then
> > they do align in all scales (picture with the blue vector layer).
> >
> > It doesn't look like a problem of precision of the transformation from
> > 3857 to 4325 because it's way off. 
> > Is that a bug or am I missing something here?
> >
> > Kind regards,
> > Idan.
> >
> >
> >
> > ___
> > Qgis-user mailing list
> > Qgis-user@lists.osgeo.org <mailto:Qgis-user@lists.osgeo.org>
> > List info: https://lists.osgeo.org/mailman/listinfo/qgis-user
> <https://lists.osgeo.org/mailman/listinfo/qgis-user>
> > Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-user
> <https://lists.osgeo.org/mailman/listinfo/qgis-user>
> >
> 
> 
> 
> --
> Dr. Benjamin Ducke
> Deutsches Archäologisches Institut (DAI)
> Zentrale Berlin, IT-Referat
> * Projekt "Stunde Null" *
> ___
> Qgis-user mailing list
> Qgis-user@lists.osgeo.org <mailto:Qgis-user@lists.osgeo.org>
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> 

Re: [Qgis-user] Pseudo Mercator(OSM) @ EPSG:4326 bug?

[Idan Miara]

Thanks for your reply,
How can I check if QGIS is applying the transformation or if it asks the
service to provide the tiles in 4326?

On 5 Mar 2018 11:17,  wrote:

> Most likely the service you are using is only able to provide its maptiles
> in 3857 and does not respond to the QGIS request to provide them in 4326
> (or responds, but incorrectly)...
>
>
>
>
>
> --
>
> Barend Köbben
>
>
>
> On 05/03/2018, 09:39, "Qgis-user on behalf of Idan Miara" <
> qgis-user-boun...@lists.osgeo.org on behalf of i...@miara.com> wrote:
>
>
>
> Hi,
>
>
>
> I might have found a bug related to transformation of layer CRS from EPSG:3857
> (Pseudo Mercator) to EPSG:4325 (WGS84 Geo).
>
> I'm attaching a few images to demonstrate the issue.
>
>
>
> Steps to reproduce:
>
> I've load OSM in QGIS 2.18.16 (or 3.0,same results)
>
> via Tile Server (XYZ):
>
> https://a.tile.openstreetmap.org/{z}/{x}/{y}.png
>
>
>
> Then set the CRS to EPSG:4326 (WGS84 Geo)
>
>
>
> I've also loaded a global bounds vector layer (EPSG:4326)
>
>
>
> In scale 1:100,000,000 it seems that the Pseudo Mercator transformation to
> 4326 is flawed, as the OSM and the vectors are not aligned.
>
> In scale 1:50,000,000 it seems OK when the extent is the middle of the
> map, but if I pan to the south/north it seems distorted again.
>
>
>
> If I set the project CRS to EPSG:3857 (Pseudo Mercator) as the CRS of the
> OSM tiles, so the vector layer would be transformed instead, then they do
> align in all scales (picture with the blue vector layer).
>
>
>
> It doesn't look like a problem of precision of the transformation from
> 3857 to 4325 because it's way off.
>
> Is that a bug or am I missing something here?
>
>
>
> Kind regards,
>
> Idan.
>
>
>
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Re: [Qgis-user] Pseudo Mercator(OSM) @ EPSG:4326 bug?

[Idan Miara]

Thanks for you reply,
Since the problem exist also in 2.18 I don't think it is related with PROJ
5.0, Right?

On 5 Mar 2018 12:39, "Kristian Evers" <kr...@sdfe.dk> wrote:

> If you are using PROJ 5.0.0 it is likely to be caused by this known issue:
>
> https://github.com/OSGeo/proj.4/issues/834
>
> /Kristian
>
> -Oprindelig meddelelse-
> Fra: Qgis-user [mailto:qgis-user-boun...@lists.osgeo.org] På vegne af
> Benjamin Ducke
> Sendt: 5. marts 2018 10:18
> Til: qgis-user@lists.osgeo.org
> Emne: Re: [Qgis-user] Pseudo Mercator(OSM) @ EPSG:4326 bug?
>
> Could it be this:
>
> http://proj4.org/faq.html#changing-ellipsoid-why-can-t-
> i-convert-from-wgs84-to-google-earth-virtual-globe-mercator
>
> ?
>
> The further you get from the equator, the more
> obvious the discrepancy on the Y axis.
>
> Best,
>
> Ben
>
> On 05/03/18 09:38, Idan Miara wrote:
> > Hi,
> >
> > I might have found a bug related to transformation of layer CRS
> > from EPSG:3857 (Pseudo Mercator) to EPSG:4325 (WGS84 Geo).
> > I'm attaching a few images to demonstrate the issue.
> >
> > Steps to reproduce:
> > I've load OSM in QGIS 2.18.16 (or 3.0,same results)
> > via Tile Server (XYZ):
> > https://a.tile.openstreetmap.org/{z}/{x}/{y}.png
> > <https://a.tile.openstreetmap.org/%7Bz%7D/%7Bx%7D/%7By%7D.png>
> >
> > Then set the CRS to EPSG:4326 (WGS84 Geo)
> >
> > I've also loaded a global bounds vector layer (EPSG:4326)
> >
> > In scale 1:100,000,000 it seems that the Pseudo Mercator transformation
> > to 4326 is flawed, as the OSM and the vectors are not aligned.
> > In scale 1:50,000,000 it seems OK when the extent is the middle of the
> > map, but if I pan to the south/north it seems distorted again.
> >
> > If I set the project CRS to EPSG:3857 (Pseudo Mercator) as the CRS of
> > the OSM tiles, so the vector layer would be transformed instead, then
> > they do align in all scales (picture with the blue vector layer).
> >
> > It doesn't look like a problem of precision of the transformation from
> > 3857 to 4325 because it's way off.
> > Is that a bug or am I missing something here?
> >
> > Kind regards,
> > Idan.
> >
> >
> >
> > ___
> > Qgis-user mailing list
> > Qgis-user@lists.osgeo.org
> > List info: https://lists.osgeo.org/mailman/listinfo/qgis-user
> > Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-user
> >
>
>
>
> --
> Dr. Benjamin Ducke
> Deutsches Archäologisches Institut (DAI)
> Zentrale Berlin, IT-Referat
> * Projekt "Stunde Null" *
> ___
> Qgis-user mailing list
> Qgis-user@lists.osgeo.org
> List info: https://lists.osgeo.org/mailman/listinfo/qgis-user
> Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-user
> ___
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> List info: https://lists.osgeo.org/mailman/listinfo/qgis-user
> Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-user
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Re: [Qgis-user] Pseudo Mercator(OSM) @ EPSG:4326 bug?

[Kristian Evers]

If you are using PROJ 5.0.0 it is likely to be caused by this known issue:

https://github.com/OSGeo/proj.4/issues/834

/Kristian

-Oprindelig meddelelse-
Fra: Qgis-user [mailto:qgis-user-boun...@lists.osgeo.org] På vegne af Benjamin 
Ducke
Sendt: 5. marts 2018 10:18
Til: qgis-user@lists.osgeo.org
Emne: Re: [Qgis-user] Pseudo Mercator(OSM) @ EPSG:4326 bug?

Could it be this:

http://proj4.org/faq.html#changing-ellipsoid-why-can-t-i-convert-from-wgs84-to-google-earth-virtual-globe-mercator

?

The further you get from the equator, the more
obvious the discrepancy on the Y axis.

Best,

Ben

On 05/03/18 09:38, Idan Miara wrote:
> Hi,
> 
> I might have found a bug related to transformation of layer CRS
> from EPSG:3857 (Pseudo Mercator) to EPSG:4325 (WGS84 Geo).
> I'm attaching a few images to demonstrate the issue. 
> 
> Steps to reproduce:
> I've load OSM in QGIS 2.18.16 (or 3.0,same results)
> via Tile Server (XYZ):
> https://a.tile.openstreetmap.org/{z}/{x}/{y}.png
> <https://a.tile.openstreetmap.org/%7Bz%7D/%7Bx%7D/%7By%7D.png>
> 
> Then set the CRS to EPSG:4326 (WGS84 Geo)
> 
> I've also loaded a global bounds vector layer (EPSG:4326)
> 
> In scale 1:100,000,000 it seems that the Pseudo Mercator transformation
> to 4326 is flawed, as the OSM and the vectors are not aligned.
> In scale 1:50,000,000 it seems OK when the extent is the middle of the
> map, but if I pan to the south/north it seems distorted again.
> 
> If I set the project CRS to EPSG:3857 (Pseudo Mercator) as the CRS of
> the OSM tiles, so the vector layer would be transformed instead, then
> they do align in all scales (picture with the blue vector layer).
> 
> It doesn't look like a problem of precision of the transformation from
> 3857 to 4325 because it's way off. 
> Is that a bug or am I missing something here?
> 
> Kind regards,
> Idan.
> 
> 
> 
> ___
> Qgis-user mailing list
> Qgis-user@lists.osgeo.org
> List info: https://lists.osgeo.org/mailman/listinfo/qgis-user
> Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-user
> 



-- 
Dr. Benjamin Ducke
Deutsches Archäologisches Institut (DAI)
Zentrale Berlin, IT-Referat
* Projekt "Stunde Null" *
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Re: [Qgis-user] Pseudo Mercator(OSM) @ EPSG:4326 bug?

[Benjamin Ducke]

Could it be this:

http://proj4.org/faq.html#changing-ellipsoid-why-can-t-i-convert-from-wgs84-to-google-earth-virtual-globe-mercator

?

The further you get from the equator, the more
obvious the discrepancy on the Y axis.

Best,

Ben

On 05/03/18 09:38, Idan Miara wrote:
> Hi,
> 
> I might have found a bug related to transformation of layer CRS
> from EPSG:3857 (Pseudo Mercator) to EPSG:4325 (WGS84 Geo).
> I'm attaching a few images to demonstrate the issue. 
> 
> Steps to reproduce:
> I've load OSM in QGIS 2.18.16 (or 3.0,same results)
> via Tile Server (XYZ):
> https://a.tile.openstreetmap.org/{z}/{x}/{y}.png
> 
> 
> Then set the CRS to EPSG:4326 (WGS84 Geo)
> 
> I've also loaded a global bounds vector layer (EPSG:4326)
> 
> In scale 1:100,000,000 it seems that the Pseudo Mercator transformation
> to 4326 is flawed, as the OSM and the vectors are not aligned.
> In scale 1:50,000,000 it seems OK when the extent is the middle of the
> map, but if I pan to the south/north it seems distorted again.
> 
> If I set the project CRS to EPSG:3857 (Pseudo Mercator) as the CRS of
> the OSM tiles, so the vector layer would be transformed instead, then
> they do align in all scales (picture with the blue vector layer).
> 
> It doesn't look like a problem of precision of the transformation from
> 3857 to 4325 because it's way off. 
> Is that a bug or am I missing something here?
> 
> Kind regards,
> Idan.
> 
> 
> 
> ___
> Qgis-user mailing list
> Qgis-user@lists.osgeo.org
> List info: https://lists.osgeo.org/mailman/listinfo/qgis-user
> Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-user
> 



-- 
Dr. Benjamin Ducke
Deutsches Archäologisches Institut (DAI)
Zentrale Berlin, IT-Referat
* Projekt "Stunde Null" *
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Re: [Qgis-user] Pseudo Mercator(OSM) @ EPSG:4326 bug?

[Idan Miara]

 Hi,

I might have found a bug related to transformation of layer CRS from EPSG:3857
(Pseudo Mercator) to EPSG:4325 (WGS84 Geo).
I'm attaching a few images to demonstrate the issue.

Steps to reproduce:
I've load OSM in QGIS 2.18.16 (or 3.0,same results)
via Tile Server (XYZ):
https://a.tile.openstreetmap.org/{z}/{x}/{y}.png

Then set the CRS to EPSG:4326 (WGS84 Geo)

I've also loaded a global bounds vector layer (EPSG:4326)

In scale 1:100,000,000 it seems that the Pseudo Mercator transformation to
4326 is flawed, as the OSM and the vectors are not aligned.
In scale 1:50,000,000 it seems OK when the extent is the middle of the map,
but if I pan to the south/north it seems distorted again.

If I set the project CRS to EPSG:3857 (Pseudo Mercator) as the CRS of the
OSM tiles, so the vector layer would be transformed instead, then they do
align in all scales (picture with the blue vector layer).

It doesn't look like a problem of precision of the transformation from 3857
to 4325 because it's way off.
Is that a bug or am I missing something here?

Kind regards,
Idan.
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