Identify coordinate system

classic Classic list List threaded Threaded
12 messages Options
Reply | Threaded
Open this post in threaded view
|

Identify coordinate system

Zoltan Szecsei
Hi Listers,
I've been asked o help a school-going daughter of a friend of mine in Doha (yes, this is "AfricaList" :-/  )
She has been given a shapefile without a projection file. The area is Al Wakrah, just South of Doha airport.

The numeric values of the geometry coords are around 560000, 2782000 - the second value looked like a distance from the Equator, so I tried UTM 39N
The scaling seems wrong, and it does not align with the coastline (QND95) shapefile I have.
(I also tried EPSG:27039)


As you can see, projection-sleuthing is not one of my strengths.
Can anyone point me in a direction to try and solve this?

Thanks in advance.

Kind regards,
Zoltan


-- 

=============================================
Zoltan Szecsei GPrGISc 0031
Geograph (Pty) Ltd.
GIS and Photogrammetric Services

P.O. Box 7, Muizenberg 7950, South Africa.

Mobile: +27-83-6004028
Qatar:  +974 5083 2722     www.geograph.co.za
=============================================

_______________________________________________
Africa mailing list
[hidden email]
You can UNSUBSCRIBE at https://lists.osgeo.org/mailman/listinfo/africa
Reply | Threaded
Open this post in threaded view
|

Re: Identify coordinate system

Hermanus Brynard
Zoltan
Have you tired the 

EPSG:28600


Manie Brynard

On Thu, Jul 11, 2019 at 6:33 PM Zoltan Szecsei <[hidden email]> wrote:
Hi Listers,
I've been asked o help a school-going daughter of a friend of mine in Doha (yes, this is "AfricaList" :-/  )
She has been given a shapefile without a projection file. The area is Al Wakrah, just South of Doha airport.

The numeric values of the geometry coords are around 560000, 2782000 - the second value looked like a distance from the Equator, so I tried UTM 39N
The scaling seems wrong, and it does not align with the coastline (QND95) shapefile I have.
(I also tried EPSG:27039)


As you can see, projection-sleuthing is not one of my strengths.
Can anyone point me in a direction to try and solve this?

Thanks in advance.

Kind regards,
Zoltan


-- 

=============================================
Zoltan Szecsei GPrGISc 0031
Geograph (Pty) Ltd.
GIS and Photogrammetric Services

P.O. Box 7, Muizenberg 7950, South Africa.

Mobile: +27-83-6004028
Qatar:  +974 5083 2722     www.geograph.co.za
=============================================
_______________________________________________
Africa mailing list
[hidden email]
You can UNSUBSCRIBE at https://lists.osgeo.org/mailman/listinfo/africa

_______________________________________________
Africa mailing list
[hidden email]
You can UNSUBSCRIBE at https://lists.osgeo.org/mailman/listinfo/africa
Reply | Threaded
Open this post in threaded view
|

Re: Identify coordinate system

Basson, FC
In reply to this post by Zoltan Szecsei

Hi Zoltan

 

This page provides a nice list of possibilities: https://epsg.io/?q=Qatar%20kind%3APROJCRS

Click on the “Get position on a map” link for each projection to compare.

It seems like it must be EPSG 27039 or EPSG 32639.

 

Regards

FC Basson

 

From: Africa [mailto:[hidden email]] On Behalf Of Zoltan Szecsei
Sent: 11 July 2019 05:52 PM
To: [hidden email]
Subject: [OSGeo Africa] Identify coordinate system

 

Hi Listers,
I've been asked o help a school-going daughter of a friend of mine in Doha (yes, this is "AfricaList" :-/  )
She has been given a shapefile without a projection file. The area is Al Wakrah, just South of Doha airport.

The numeric values of the geometry coords are around 560000, 2782000 - the second value looked like a distance from the Equator, so I tried UTM 39N
The scaling seems wrong, and it does not align with the coastline (QND95) shapefile I have.
(I also tried EPSG:27039)


As you can see, projection-sleuthing is not one of my strengths.
Can anyone point me in a direction to try and solve this?

Thanks in advance.

Kind regards,
Zoltan

 

-- 
 
=============================================
Zoltan Szecsei GPrGISc 0031
Geograph (Pty) Ltd.
GIS and Photogrammetric Services
 
P.O. Box 7, Muizenberg 7950, South Africa.
 
Mobile: +27-83-6004028
Qatar:  +974 5083 2722     www.geograph.co.za
=============================================
"All views or opinions expressed in this electronic message and its attachments are the view of the sender and do not necessarily reflect the views and opinions of the Western Cape Government (the WCG). No employee of the WCG is entitled to conclude a binding contract on behalf of the WCG unless he/she is an accounting officer of the WCG, or his or her authorised representative. The information contained in this message and its attachments may be confidential or privileged and is for the use of the named recipient only, except where the sender specifically states otherwise. If you are not the intended recipient you may not copy or deliver this message to anyone."

Disclaimer

The information contained in this communication from the sender is confidential. It is intended solely for use by the recipient and others authorized to receive it. If you are not the recipient, you are hereby notified that any disclosure, copying, distribution or taking action in relation of the contents of this information is strictly prohibited and may be unlawful.

This email has been scanned for viruses and malware, and may have been automatically archived by Mimecast Ltd, an innovator in Software as a Service (SaaS) for business. Providing a safer and more useful place for your human generated data. Specializing in; Security, archiving and compliance. To find out more Click Here.


_______________________________________________
Africa mailing list
[hidden email]
You can UNSUBSCRIBE at https://lists.osgeo.org/mailman/listinfo/africa
Reply | Threaded
Open this post in threaded view
|

Re: Identify coordinate system

Zoltan Szecsei
In reply to this post by Hermanus Brynard
Hi Manie,
Thanks for the idea.

The current system in use is QND95 - the one you are suggesting  (I see) is from 1976, and its origin is "too close".
(Yes, I still tried it)

Looking at the numeric values of the coords, I am expecting something with an origin some 500Km West of Doha, and on the Equator.

And then of course I also need to consider the possibility that the coords in the shapefile are non-sensical, so I'm trying to find out its source....


Thanks and keep well,
Zoltan

On 2019/07/12 09:23, Hermanus Brynard wrote:
Zoltan
Have you tired the 

EPSG:28600


Manie Brynard

On Thu, Jul 11, 2019 at 6:33 PM Zoltan Szecsei <[hidden email]> wrote:
Hi Listers,
I've been asked o help a school-going daughter of a friend of mine in Doha (yes, this is "AfricaList" :-/  )
She has been given a shapefile without a projection file. The area is Al Wakrah, just South of Doha airport.

The numeric values of the geometry coords are around 560000, 2782000 - the second value looked like a distance from the Equator, so I tried UTM 39N
The scaling seems wrong, and it does not align with the coastline (QND95) shapefile I have.
(I also tried EPSG:27039)


As you can see, projection-sleuthing is not one of my strengths.
Can anyone point me in a direction to try and solve this?

Thanks in advance.

Kind regards,
Zoltan


-- 

=============================================
Zoltan Szecsei GPrGISc 0031
Geograph (Pty) Ltd.
GIS and Photogrammetric Services

P.O. Box 7, Muizenberg 7950, South Africa.

Mobile: +27-83-6004028
Qatar:  +974 5083 2722     www.geograph.co.za
=============================================
_______________________________________________
Africa mailing list
[hidden email]
You can UNSUBSCRIBE at https://lists.osgeo.org/mailman/listinfo/africa

_______________________________________________
Africa mailing list
[hidden email]
You can UNSUBSCRIBE at https://lists.osgeo.org/mailman/listinfo/africa
-- 

=============================================
Zoltan Szecsei GPrGISc 0031
Geograph (Pty) Ltd.
GIS and Photogrammetric Services

P.O. Box 7, Muizenberg 7950, South Africa.

Mobile: +27-83-6004028
Qatar:  +974 5083 2722     www.geograph.co.za
=============================================

_______________________________________________
Africa mailing list
[hidden email]
You can UNSUBSCRIBE at https://lists.osgeo.org/mailman/listinfo/africa
Reply | Threaded
Open this post in threaded view
|

Re: Identify coordinate system

Hermanus Brynard
Zoltan
You mention 500k makes me think there could be a UTM transformation which usully adds a 500000m easting or westing and 10 000 000m northing to avoid negative numbers.

Can you send me the shapefile.
Manie


On Fri, Jul 12, 2019 at 8:57 AM Zoltan Szecsei <[hidden email]> wrote:
Hi Manie,
Thanks for the idea.

The current system in use is QND95 - the one you are suggesting  (I see) is from 1976, and its origin is "too close".
(Yes, I still tried it)

Looking at the numeric values of the coords, I am expecting something with an origin some 500Km West of Doha, and on the Equator.

And then of course I also need to consider the possibility that the coords in the shapefile are non-sensical, so I'm trying to find out its source....


Thanks and keep well,
Zoltan

On 2019/07/12 09:23, Hermanus Brynard wrote:
Zoltan
Have you tired the 

EPSG:28600


Manie Brynard

On Thu, Jul 11, 2019 at 6:33 PM Zoltan Szecsei <[hidden email]> wrote:
Hi Listers,
I've been asked o help a school-going daughter of a friend of mine in Doha (yes, this is "AfricaList" :-/  )
She has been given a shapefile without a projection file. The area is Al Wakrah, just South of Doha airport.

The numeric values of the geometry coords are around 560000, 2782000 - the second value looked like a distance from the Equator, so I tried UTM 39N
The scaling seems wrong, and it does not align with the coastline (QND95) shapefile I have.
(I also tried EPSG:27039)


As you can see, projection-sleuthing is not one of my strengths.
Can anyone point me in a direction to try and solve this?

Thanks in advance.

Kind regards,
Zoltan


-- 

=============================================
Zoltan Szecsei GPrGISc 0031
Geograph (Pty) Ltd.
GIS and Photogrammetric Services

P.O. Box 7, Muizenberg 7950, South Africa.

Mobile: +27-83-6004028
Qatar:  +974 5083 2722     www.geograph.co.za
=============================================
_______________________________________________
Africa mailing list
[hidden email]
You can UNSUBSCRIBE at https://lists.osgeo.org/mailman/listinfo/africa

_______________________________________________
Africa mailing list
[hidden email]
You can UNSUBSCRIBE at https://lists.osgeo.org/mailman/listinfo/africa
-- 

=============================================
Zoltan Szecsei GPrGISc 0031
Geograph (Pty) Ltd.
GIS and Photogrammetric Services

P.O. Box 7, Muizenberg 7950, South Africa.

Mobile: +27-83-6004028
Qatar:  +974 5083 2722     www.geograph.co.za
=============================================
_______________________________________________
Africa mailing list
[hidden email]
You can UNSUBSCRIBE at https://lists.osgeo.org/mailman/listinfo/africa

_______________________________________________
Africa mailing list
[hidden email]
You can UNSUBSCRIBE at https://lists.osgeo.org/mailman/listinfo/africa
Reply | Threaded
Open this post in threaded view
|

Re: Identify coordinate system

Zoltan Szecsei
Hmmm....Ja.
But querying the source of the data might save all of us from getting a hard-earned 'Sherlock Holmes' badge :-)

On 2019/07/12 10:02, Hermanus Brynard wrote:
Zoltan
You mention 500k makes me think there could be a UTM transformation which usully adds a 500000m easting or westing and 10 000 000m northing to avoid negative numbers.

Can you send me the shapefile.
Manie


On Fri, Jul 12, 2019 at 8:57 AM Zoltan Szecsei <[hidden email]> wrote:
Hi Manie,
Thanks for the idea.

The current system in use is QND95 - the one you are suggesting  (I see) is from 1976, and its origin is "too close".
(Yes, I still tried it)

Looking at the numeric values of the coords, I am expecting something with an origin some 500Km West of Doha, and on the Equator.

And then of course I also need to consider the possibility that the coords in the shapefile are non-sensical, so I'm trying to find out its source....


Thanks and keep well,
Zoltan

On 2019/07/12 09:23, Hermanus Brynard wrote:
Zoltan
Have you tired the 

EPSG:28600


Manie Brynard

On Thu, Jul 11, 2019 at 6:33 PM Zoltan Szecsei <[hidden email]> wrote:
Hi Listers,
I've been asked o help a school-going daughter of a friend of mine in Doha (yes, this is "AfricaList" :-/  )
She has been given a shapefile without a projection file. The area is Al Wakrah, just South of Doha airport.

The numeric values of the geometry coords are around 560000, 2782000 - the second value looked like a distance from the Equator, so I tried UTM 39N
The scaling seems wrong, and it does not align with the coastline (QND95) shapefile I have.
(I also tried EPSG:27039)


As you can see, projection-sleuthing is not one of my strengths.
Can anyone point me in a direction to try and solve this?

Thanks in advance.

Kind regards,
Zoltan


-- 

=============================================
Zoltan Szecsei GPrGISc 0031
Geograph (Pty) Ltd.
GIS and Photogrammetric Services

P.O. Box 7, Muizenberg 7950, South Africa.

Mobile: +27-83-6004028
Qatar:  +974 5083 2722     www.geograph.co.za
=============================================
_______________________________________________
Africa mailing list
[hidden email]
You can UNSUBSCRIBE at https://lists.osgeo.org/mailman/listinfo/africa

_______________________________________________
Africa mailing list
[hidden email]
You can UNSUBSCRIBE at https://lists.osgeo.org/mailman/listinfo/africa
-- 

=============================================
Zoltan Szecsei GPrGISc 0031
Geograph (Pty) Ltd.
GIS and Photogrammetric Services

P.O. Box 7, Muizenberg 7950, South Africa.

Mobile: +27-83-6004028
Qatar:  +974 5083 2722     www.geograph.co.za
=============================================
_______________________________________________
Africa mailing list
[hidden email]
You can UNSUBSCRIBE at https://lists.osgeo.org/mailman/listinfo/africa

_______________________________________________
Africa mailing list
[hidden email]
You can UNSUBSCRIBE at https://lists.osgeo.org/mailman/listinfo/africa
-- 

=============================================
Zoltan Szecsei GPrGISc 0031
Geograph (Pty) Ltd.
GIS and Photogrammetric Services

P.O. Box 7, Muizenberg 7950, South Africa.

Mobile: +27-83-6004028
Qatar:  +974 5083 2722     www.geograph.co.za
=============================================

_______________________________________________
Africa mailing list
[hidden email]
You can UNSUBSCRIBE at https://lists.osgeo.org/mailman/listinfo/africa
Reply | Threaded
Open this post in threaded view
|

Re: Identify coordinate system

Abraham Parbhunath

Hi Zoltan. 

 

Do you know approximately where  the shape file is supposed to be relative to other datasets?  Can you find common points between this unknown dataset and the others you have in that area?  If there is common data, you could try a helmert transformation which should give you all the various parameters (e.g. scale swing rotation…..) and you could manually input these for your data and see where it plots. If it matches your data, then you could just manually define it using your known dataset.  I assume there’s no metadata/xml file associated with the shapefile that can give a hint as to its origin also…?

 

If not, then happy hunting J

 

Regards

Abraham Parbhunath

 



From: Africa <[hidden email]> On Behalf Of Zoltan Szecsei
Sent: Friday, 12 July 2019 09:12
To: [hidden email]
Subject: Re: [OSGeo Africa] Identify coordinate system

 

Hmmm....Ja.
But querying the source of the data might save all of us from getting a hard-earned 'Sherlock Holmes' badge :-)

On 2019/07/12 10:02, Hermanus Brynard wrote:

Zoltan

You mention 500k makes me think there could be a UTM transformation which usully adds a 500000m easting or westing and 10 000 000m northing to avoid negative numbers.

 

Can you send me the shapefile.

Manie

 

 

On Fri, Jul 12, 2019 at 8:57 AM Zoltan Szecsei <[hidden email]> wrote:

Hi Manie,
Thanks for the idea.

The current system in use is QND95 - the one you are suggesting  (I see) is from 1976, and its origin is "too close".
(Yes, I still tried it)

Looking at the numeric values of the coords, I am expecting something with an origin some 500Km West of Doha, and on the Equator.

And then of course I also need to consider the possibility that the coords in the shapefile are non-sensical, so I'm trying to find out its source....


Thanks and keep well,
Zoltan

On 2019/07/12 09:23, Hermanus Brynard wrote:

Zoltan

Have you tired the 

 

EPSG:28600

 

Manie Brynard

 

On Thu, Jul 11, 2019 at 6:33 PM Zoltan Szecsei <[hidden email]> wrote:

Hi Listers,
I've been asked o help a school-going daughter of a friend of mine in Doha (yes, this is "AfricaList" :-/  )
She has been given a shapefile without a projection file. The area is Al Wakrah, just South of Doha airport.

The numeric values of the geometry coords are around 560000, 2782000 - the second value looked like a distance from the Equator, so I tried UTM 39N
The scaling seems wrong, and it does not align with the coastline (QND95) shapefile I have.
(I also tried EPSG:27039)


As you can see, projection-sleuthing is not one of my strengths.
Can anyone point me in a direction to try and solve this?

Thanks in advance.

Kind regards,
Zoltan

 

-- 
 
=============================================
Zoltan Szecsei GPrGISc 0031
Geograph (Pty) Ltd.
GIS and Photogrammetric Services
 
P.O. Box 7, Muizenberg 7950, South Africa.
 
Mobile: +27-83-6004028
Qatar:  +974 5083 2722     www.geograph.co.za
=============================================

_______________________________________________
Africa mailing list
[hidden email]
You can UNSUBSCRIBE at https://lists.osgeo.org/mailman/listinfo/africa



_______________________________________________
Africa mailing list
[hidden email]
You can UNSUBSCRIBE at https://lists.osgeo.org/mailman/listinfo/africa
-- 
 
=============================================
Zoltan Szecsei GPrGISc 0031
Geograph (Pty) Ltd.
GIS and Photogrammetric Services
 
P.O. Box 7, Muizenberg 7950, South Africa.
 
Mobile: +27-83-6004028
Qatar:  +974 5083 2722     www.geograph.co.za
=============================================

_______________________________________________
Africa mailing list
[hidden email]
You can UNSUBSCRIBE at https://lists.osgeo.org/mailman/listinfo/africa



_______________________________________________
Africa mailing list
[hidden email]
You can UNSUBSCRIBE at https://lists.osgeo.org/mailman/listinfo/africa
-- 
 
=============================================
Zoltan Szecsei GPrGISc 0031
Geograph (Pty) Ltd.
GIS and Photogrammetric Services
 
P.O. Box 7, Muizenberg 7950, South Africa.
 
Mobile: +27-83-6004028
Qatar:  +974 5083 2722     www.geograph.co.za
=============================================


Signature Version dd/mm/yyyy hh:mm
NB: This Email and its contents are subject to the Eskom Holdings SOC Ltd EMAIL LEGAL NOTICE which can be viewed at http://www.eskom.co.za/Pages/Email_Legal_Spam_Disclaimer.aspx
_______________________________________________
Africa mailing list
[hidden email]
You can UNSUBSCRIBE at https://lists.osgeo.org/mailman/listinfo/africa
Reply | Threaded
Open this post in threaded view
|

Re: Identify coordinate system

Tim Sutton-6
In reply to this post by Zoltan Szecsei
Hi

Also consider that some countries (e.g. UK) use a false easting and northing so that the CRS origin starts from 0,0 just outside the sovereign territory….

Regards

Tim

On 12 Jul 2019, at 08:11, Zoltan Szecsei <[hidden email]> wrote:

Hmmm....Ja.
But querying the source of the data might save all of us from getting a hard-earned 'Sherlock Holmes' badge :-)

On 2019/07/12 10:02, Hermanus Brynard wrote:
Zoltan
You mention 500k makes me think there could be a UTM transformation which usully adds a 500000m easting or westing and 10 000 000m northing to avoid negative numbers.

Can you send me the shapefile.
Manie


On Fri, Jul 12, 2019 at 8:57 AM Zoltan Szecsei <[hidden email]> wrote:
Hi Manie,
Thanks for the idea.

The current system in use is QND95 - the one you are suggesting  (I see) is from 1976, and its origin is "too close".
(Yes, I still tried it)

Looking at the numeric values of the coords, I am expecting something with an origin some 500Km West of Doha, and on the Equator.

And then of course I also need to consider the possibility that the coords in the shapefile are non-sensical, so I'm trying to find out its source....


Thanks and keep well,
Zoltan

On 2019/07/12 09:23, Hermanus Brynard wrote:
Zoltan
Have you tired the 

EPSG:28600


Manie Brynard

On Thu, Jul 11, 2019 at 6:33 PM Zoltan Szecsei <[hidden email]> wrote:
Hi Listers,
I've been asked o help a school-going daughter of a friend of mine in Doha (yes, this is "AfricaList" :-/  )
She has been given a shapefile without a projection file. The area is Al Wakrah, just South of Doha airport.

The numeric values of the geometry coords are around 560000, 2782000 - the second value looked like a distance from the Equator, so I tried UTM 39N
The scaling seems wrong, and it does not align with the coastline (QND95) shapefile I have.
(I also tried EPSG:27039)


As you can see, projection-sleuthing is not one of my strengths.
Can anyone point me in a direction to try and solve this?

Thanks in advance.

Kind regards,
Zoltan


-- 

=============================================
Zoltan Szecsei GPrGISc 0031
Geograph (Pty) Ltd.
GIS and Photogrammetric Services

P.O. Box 7, Muizenberg 7950, South Africa.

Mobile: +27-83-6004028
Qatar:  +974 5083 2722     www.geograph.co.za
=============================================
_______________________________________________
Africa mailing list
[hidden email]
You can UNSUBSCRIBE at https://lists.osgeo.org/mailman/listinfo/africa

_______________________________________________
Africa mailing list
[hidden email]
You can UNSUBSCRIBE at https://lists.osgeo.org/mailman/listinfo/africa
-- 

=============================================
Zoltan Szecsei GPrGISc 0031
Geograph (Pty) Ltd.
GIS and Photogrammetric Services

P.O. Box 7, Muizenberg 7950, South Africa.

Mobile: +27-83-6004028
Qatar:  +974 5083 2722     www.geograph.co.za
=============================================
_______________________________________________
Africa mailing list
[hidden email]
You can UNSUBSCRIBE at https://lists.osgeo.org/mailman/listinfo/africa

_______________________________________________
Africa mailing list
[hidden email]
You can UNSUBSCRIBE at https://lists.osgeo.org/mailman/listinfo/africa
-- 

=============================================
Zoltan Szecsei GPrGISc 0031
Geograph (Pty) Ltd.
GIS and Photogrammetric Services

P.O. Box 7, Muizenberg 7950, South Africa.

Mobile: +27-83-6004028
Qatar:  +974 5083 2722     www.geograph.co.za
=============================================
_______________________________________________
Africa mailing list
[hidden email]
You can UNSUBSCRIBE at https://lists.osgeo.org/mailman/listinfo/africa









Tim Sutton

Co-founder: Kartoza
Ex Project chair: QGIS.org

Visit http://kartoza.com to find out about open source:

Desktop GIS programming services
Geospatial web development
GIS Training
Consulting Services

Skype: timlinux 
IRC: timlinux on #qgis at freenode.net

I'd love to connect. Here's my calendar link to make finding time easy.


_______________________________________________
Africa mailing list
[hidden email]
You can UNSUBSCRIBE at https://lists.osgeo.org/mailman/listinfo/africa
Reply | Threaded
Open this post in threaded view
|

Fwd: Identify coordinate system

Tim Sutton-6

Hi

Also consider that some countries (e.g. UK) use a false easting and northing so that the CRS origin starts from 0,0 just outside the sovereign territory….

Regards

Tim








Tim Sutton

Co-founder: Kartoza
Ex Project chair: QGIS.org

Visit http://kartoza.com to find out about open source:

Desktop GIS programming services
Geospatial web development
GIS Training
Consulting Services

Skype: timlinux 
IRC: timlinux on #qgis at freenode.net

I'd love to connect. Here's my calendar link to make finding time easy.


_______________________________________________
Africa mailing list
[hidden email]
You can UNSUBSCRIBE at https://lists.osgeo.org/mailman/listinfo/africa
Reply | Threaded
Open this post in threaded view
|

Re: Fwd: Identify coordinate system - SOLVED

Zoltan Szecsei
HI List/Tim,
Thanks to all who responded.

My first guess, UTM39N, based on the numeric value of the coordinates and the fact that the area was somewhere in Doha, was correct.
But, when I looked at the result, the polygons did not match nicely with the Qatar coastline.

Today I get confirmation from the original source, that it is in fact UTM39N, and.....wait for it...(drum-roll).......the polygons represent CLOUD COVER.    (Doh! of course they don't follow the coastline)

So, it is obviously never too late to learn that asking what the vectors represent, might be key to solving your problem.

Big thanks again to all who responded.
Kind regards,
Zoltan


On 2019/07/12 21:30, Tim Sutton wrote:

Hi

Also consider that some countries (e.g. UK) use a false easting and northing so that the CRS origin starts from 0,0 just outside the sovereign territory….

Regards

Tim








Tim Sutton

Co-founder: Kartoza
Ex Project chair: QGIS.org

Visit http://kartoza.com to find out about open source:

Desktop GIS programming services
Geospatial web development
GIS Training
Consulting Services

Skype: timlinux 
IRC: timlinux on #qgis at freenode.net

I'd love to connect. Here's my calendar link to make finding time easy.


_______________________________________________
Africa mailing list
[hidden email]
You can UNSUBSCRIBE at https://lists.osgeo.org/mailman/listinfo/africa
-- 

=============================================
Zoltan Szecsei GPrGISc 0031
Geograph (Pty) Ltd.
GIS and Photogrammetric Services

P.O. Box 7, Muizenberg 7950, South Africa.

Mobile: +27-83-6004028
Qatar:  +974 5083 2722     www.geograph.co.za
=============================================

_______________________________________________
Africa mailing list
[hidden email]
You can UNSUBSCRIBE at https://lists.osgeo.org/mailman/listinfo/africa
Reply | Threaded
Open this post in threaded view
|

Re: Identify coordinate system

Zoltan Szecsei
In reply to this post by Abraham Parbhunath
See my "Solved" email to the list....

My reality was that I did not ask what the vector data represented.
My strategy of looking for what projection had its origin on the equator and some 500Km west of Doha correctly led me to UTM39N, but as I did not realise that the data was cloud cover (there were no attributes in the shapefile) I thought there was another error.


Thanks for the thought.
Regards,
Zoltan

On 2019/07/12 12:07, Abraham Parbhunath wrote:

Hi Zoltan. 

 

Do you know approximately where  the shape file is supposed to be relative to other datasets?  Can you find common points between this unknown dataset and the others you have in that area?  If there is common data, you could try a helmert transformation which should give you all the various parameters (e.g. scale swing rotation…..) and you could manually input these for your data and see where it plots. If it matches your data, then you could just manually define it using your known dataset.  I assume there’s no metadata/xml file associated with the shapefile that can give a hint as to its origin also…?

 

If not, then happy hunting J

 

Regards

Abraham Parbhunath

 



From: Africa [hidden email] On Behalf Of Zoltan Szecsei
Sent: Friday, 12 July 2019 09:12
To: [hidden email]
Subject: Re: [OSGeo Africa] Identify coordinate system

 

Hmmm....Ja.
But querying the source of the data might save all of us from getting a hard-earned 'Sherlock Holmes' badge :-)

On 2019/07/12 10:02, Hermanus Brynard wrote:

Zoltan

You mention 500k makes me think there could be a UTM transformation which usully adds a 500000m easting or westing and 10 000 000m northing to avoid negative numbers.

 

Can you send me the shapefile.

Manie

 

 

On Fri, Jul 12, 2019 at 8:57 AM Zoltan Szecsei <[hidden email]> wrote:

Hi Manie,
Thanks for the idea.

The current system in use is QND95 - the one you are suggesting  (I see) is from 1976, and its origin is "too close".
(Yes, I still tried it)

Looking at the numeric values of the coords, I am expecting something with an origin some 500Km West of Doha, and on the Equator.

And then of course I also need to consider the possibility that the coords in the shapefile are non-sensical, so I'm trying to find out its source....


Thanks and keep well,
Zoltan

On 2019/07/12 09:23, Hermanus Brynard wrote:

Zoltan

Have you tired the 

 

EPSG:28600

 

Manie Brynard

 

On Thu, Jul 11, 2019 at 6:33 PM Zoltan Szecsei <[hidden email]> wrote:

Hi Listers,
I've been asked o help a school-going daughter of a friend of mine in Doha (yes, this is "AfricaList" :-/  )
She has been given a shapefile without a projection file. The area is Al Wakrah, just South of Doha airport.

The numeric values of the geometry coords are around 560000, 2782000 - the second value looked like a distance from the Equator, so I tried UTM 39N
The scaling seems wrong, and it does not align with the coastline (QND95) shapefile I have.
(I also tried EPSG:27039)


As you can see, projection-sleuthing is not one of my strengths.
Can anyone point me in a direction to try and solve this?

Thanks in advance.

Kind regards,
Zoltan

 

-- 
 
=============================================
Zoltan Szecsei GPrGISc 0031
Geograph (Pty) Ltd.
GIS and Photogrammetric Services
 
P.O. Box 7, Muizenberg 7950, South Africa.
 
Mobile: +27-83-6004028
Qatar:  +974 5083 2722     www.geograph.co.za
=============================================

_______________________________________________
Africa mailing list
[hidden email]
You can UNSUBSCRIBE at https://lists.osgeo.org/mailman/listinfo/africa



_______________________________________________
Africa mailing list
[hidden email]
You can UNSUBSCRIBE at https://lists.osgeo.org/mailman/listinfo/africa
-- 
 
=============================================
Zoltan Szecsei GPrGISc 0031
Geograph (Pty) Ltd.
GIS and Photogrammetric Services
 
P.O. Box 7, Muizenberg 7950, South Africa.
 
Mobile: +27-83-6004028
Qatar:  +974 5083 2722     www.geograph.co.za
=============================================

_______________________________________________
Africa mailing list
[hidden email]
You can UNSUBSCRIBE at https://lists.osgeo.org/mailman/listinfo/africa



_______________________________________________
Africa mailing list
[hidden email]
You can UNSUBSCRIBE at https://lists.osgeo.org/mailman/listinfo/africa
-- 
 
=============================================
Zoltan Szecsei GPrGISc 0031
Geograph (Pty) Ltd.
GIS and Photogrammetric Services
 
P.O. Box 7, Muizenberg 7950, South Africa.
 
Mobile: +27-83-6004028
Qatar:  +974 5083 2722     www.geograph.co.za
=============================================


Signature Version dd/mm/yyyy hh:mm
NB: This Email and its contents are subject to the Eskom Holdings SOC Ltd EMAIL LEGAL NOTICE which can be viewed at http://www.eskom.co.za/Pages/Email_Legal_Spam_Disclaimer.aspx
_______________________________________________
Africa mailing list
[hidden email]
You can UNSUBSCRIBE at https://lists.osgeo.org/mailman/listinfo/africa
-- 

=============================================
Zoltan Szecsei GPrGISc 0031
Geograph (Pty) Ltd.
GIS and Photogrammetric Services

P.O. Box 7, Muizenberg 7950, South Africa.

Mobile: +27-83-6004028
Qatar:  +974 5083 2722     www.geograph.co.za
=============================================

_______________________________________________
Africa mailing list
[hidden email]
You can UNSUBSCRIBE at https://lists.osgeo.org/mailman/listinfo/africa
Reply | Threaded
Open this post in threaded view
|

Re: Fwd: Identify coordinate system - SOLVED

Tim Sutton-6
In reply to this post by Zoltan Szecsei
Hi

Great discussion anyway and very nice that you posted the solution too so we didn’t all toss and turn at night wondering what the answer was :-)

Regards

Tim

On 13 Jul 2019, at 10:40, Zoltan Szecsei <[hidden email]> wrote:

HI List/Tim,
Thanks to all who responded.

My first guess, UTM39N, based on the numeric value of the coordinates and the fact that the area was somewhere in Doha, was correct.
But, when I looked at the result, the polygons did not match nicely with the Qatar coastline.

Today I get confirmation from the original source, that it is in fact UTM39N, and.....wait for it...(drum-roll).......the polygons represent CLOUD COVER.    (Doh! of course they don't follow the coastline)

So, it is obviously never too late to learn that asking what the vectors represent, might be key to solving your problem.

Big thanks again to all who responded.
Kind regards,
Zoltan


On 2019/07/12 21:30, Tim Sutton wrote:

Hi

Also consider that some countries (e.g. UK) use a false easting and northing so that the CRS origin starts from 0,0 just outside the sovereign territory….

Regards

Tim


<KartozaNewLogoThumbnail.jpg>






Tim Sutton

Co-founder: Kartoza
Ex Project chair: QGIS.org

Visit http://kartoza.com to find out about open source:

Desktop GIS programming services
Geospatial web development
GIS Training
Consulting Services

Skype: timlinux 
IRC: timlinux on #qgis at freenode.net

I'd love to connect. Here's my calendar link to make finding time easy.


_______________________________________________
Africa mailing list
[hidden email]
You can UNSUBSCRIBE at https://lists.osgeo.org/mailman/listinfo/africa
-- 

=============================================
Zoltan Szecsei GPrGISc 0031
Geograph (Pty) Ltd.
GIS and Photogrammetric Services

P.O. Box 7, Muizenberg 7950, South Africa.

Mobile: +27-83-6004028
Qatar:  +974 5083 2722     www.geograph.co.za
=============================================
_______________________________________________
Africa mailing list
[hidden email]
You can UNSUBSCRIBE at https://lists.osgeo.org/mailman/listinfo/africa









Tim Sutton

Co-founder: Kartoza
Ex Project chair: QGIS.org

Visit http://kartoza.com to find out about open source:

Desktop GIS programming services
Geospatial web development
GIS Training
Consulting Services

Skype: timlinux 
IRC: timlinux on #qgis at freenode.net

I'd love to connect. Here's my calendar link to make finding time easy.


_______________________________________________
Africa mailing list
[hidden email]
You can UNSUBSCRIBE at https://lists.osgeo.org/mailman/listinfo/africa