Is location info included in metadata when save an image file?

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Is location info included in metadata when save an image file?

Ert Four
Does any coordinate or location data get embedded in the image file if I use Project > Save as Image or Composer > Export as Image/PDF/SVG?

I'm using QGIS version 2.14.3 Essen, although I would like to know about more recent versions, too, for when I upgrade later.

(I'm aware of the option to check "World file on" and create a separate world file. What I need is to make sure there is no identifying info whatsoever from the project file in the image file itself.)

Eg, say I have a basemap like OpenStreetMap open for a country and I load points in another layer that are inside that country. Then I zoom in on a group of points from my data layer, I turn off the basemap layer, and make a map with just my data points. I want to preserve the relative spatial relationships between my points but not reveal where in the world the map came from. If I publish this image file, might the metadata reveal the location?

For the work we do, it's critically important we not unknowingly publish specific locations.

Thank you, first time posting, very much appreciate QGIS and its community!

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Re: Is location info included in metadata when save an image file?

Alex Mandel-2
On 5/30/19 08:09, Ert Four wrote:

> Does any coordinate or location data get embedded in the image file if I use Project > Save as Image or Composer > Export as Image/PDF/SVG?
>
> I'm using QGIS version 2.14.3 Essen, although I would like to know about more recent versions, too, for when I upgrade later.
>
> (I'm aware of the option to check "World file on" and create a separate world file. What I need is to make sure there is no identifying info whatsoever from the project file in the image file itself.)
>
> Eg, say I have a basemap like OpenStreetMap open for a country and I load points in another layer that are inside that country. Then I zoom in on a group of points from my data layer, I turn off the basemap layer, and make a map with just my data points. I want to preserve the relative spatial relationships between my points but not reveal where in the world the map came from. If I publish this image file, might the metadata reveal the location?
>
> For the work we do, it's critically important we not unknowingly publish specific locations.
>
> Thank you, first time posting, very much appreciate QGIS and its community!
>
>

Save Image should be safe for this use if you do not include the world
file with a png or jpg.

I believe this is also true for Composer exports to the formats you
mention, but could easily be checked by exporting and SVG and then
viewing the SVG (XML) in a text editor.

Thanks,
Alex

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Re: Is location info included in metadata when save an image file?

Ert Four
Thank you, I didn't know SVG was XML/text based, I will check that out.

Sometimes I will need to export a PNG or JPG. Sorry, I need to be really careful, have you or has anyone reading this read the relevant parts of the code, by chance?

For now I'm taking screenshots to be sure nothing is transmitted, but that has limitations.

Thanks.


> On May 30, 2019 at 5:47 PM Alex M <[hidden email]> wrote:
>
>
> On 5/30/19 08:09, Ert Four wrote:
> > Does any coordinate or location data get embedded in the image file if I use Project > Save as Image or Composer > Export as Image/PDF/SVG?
> >
> > I'm using QGIS version 2.14.3 Essen, although I would like to know about more recent versions, too, for when I upgrade later.
> >
> > (I'm aware of the option to check "World file on" and create a separate world file. What I need is to make sure there is no identifying info whatsoever from the project file in the image file itself.)
> >
> > Eg, say I have a basemap like OpenStreetMap open for a country and I load points in another layer that are inside that country. Then I zoom in on a group of points from my data layer, I turn off the basemap layer, and make a map with just my data points. I want to preserve the relative spatial relationships between my points but not reveal where in the world the map came from. If I publish this image file, might the metadata reveal the location?
> >
> > For the work we do, it's critically important we not unknowingly publish specific locations.
> >
> > Thank you, first time posting, very much appreciate QGIS and its community!
> >
> >
>
> Save Image should be safe for this use if you do not include the world
> file with a png or jpg.
>
> I believe this is also true for Composer exports to the formats you
> mention, but could easily be checked by exporting and SVG and then
> viewing the SVG (XML) in a text editor.
>
> Thanks,
> Alex
>
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Re: Is location info included in metadata when save an image file?

Alex Mandel-2
The QGIS Developer list might be the better place to get confirmation.

For the Save as Image I think this is the code, starting around line 106
https://github.com/qgis/QGIS/blob/736e8cbbc34ef8ea4ec935851766dd295a365b1a/src/core/qgsmaprenderertask.cpp#L106

Which appears to render an image, and save. If it was geographic it
would use the ogr based data writing method.

I did not go looking for the SVG export which is Qt based.

Enjoy,
Alex

On 5/31/19 06:32, Ert Four wrote:

> Thank you, I didn't know SVG was XML/text based, I will check that out.
>
> Sometimes I will need to export a PNG or JPG. Sorry, I need to be really careful, have you or has anyone reading this read the relevant parts of the code, by chance?
>
> For now I'm taking screenshots to be sure nothing is transmitted, but that has limitations.
>
> Thanks.
>
>
>> On May 30, 2019 at 5:47 PM Alex M <[hidden email]> wrote:
>>
>>
>> On 5/30/19 08:09, Ert Four wrote:
>>> Does any coordinate or location data get embedded in the image file if I use Project > Save as Image or Composer > Export as Image/PDF/SVG?
>>>
>>> I'm using QGIS version 2.14.3 Essen, although I would like to know about more recent versions, too, for when I upgrade later.
>>>
>>> (I'm aware of the option to check "World file on" and create a separate world file. What I need is to make sure there is no identifying info whatsoever from the project file in the image file itself.)
>>>
>>> Eg, say I have a basemap like OpenStreetMap open for a country and I load points in another layer that are inside that country. Then I zoom in on a group of points from my data layer, I turn off the basemap layer, and make a map with just my data points. I want to preserve the relative spatial relationships between my points but not reveal where in the world the map came from. If I publish this image file, might the metadata reveal the location?
>>>
>>> For the work we do, it's critically important we not unknowingly publish specific locations.
>>>
>>> Thank you, first time posting, very much appreciate QGIS and its community!
>>>
>>>
>>
>> Save Image should be safe for this use if you do not include the world
>> file with a png or jpg.
>>
>> I believe this is also true for Composer exports to the formats you
>> mention, but could easily be checked by exporting and SVG and then
>> viewing the SVG (XML) in a text editor.
>>
>> Thanks,
>> Alex
>>
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Re: Is location info included in metadata when save an image file?

Fernando M. Roxo da Motta
In reply to this post by Ert Four
On Thu, 30 May 2019 17:09:59 +0200 (CEST), Ert Four <[hidden email]>
wrote:


> Does any coordinate or location data get embedded in the image file
> if I use Project > Save as Image or Composer > Export as
> Image/PDF/SVG?
>
> I'm using QGIS version 2.14.3 Essen, although I would like to know
> about more recent versions, too, for when I upgrade later.
>
> (I'm aware of the option to check "World file on" and create a
> separate world file. What I need is to make sure there is no
> identifying info whatsoever from the project file in the image file
> itself.)
>
> Eg, say I have a basemap like OpenStreetMap open for a country and I
> load points in another layer that are inside that country. Then I
> zoom in on a group of points from my data layer, I turn off the
> basemap layer, and make a map with just my data points. I want to
> preserve the relative spatial relationships between my points but not
> reveal where in the world the map came from. If I publish this image
> file, might the metadata reveal the location?
>
> For the work we do, it's critically important we not unknowingly
> publish specific locations.
>

  AFAIK, if you save in PNG or JPEG format no coordinate information is
stored in metadata of the image:

$ exiftool Inhambu.jpg
ExifTool Version Number         : 10.80
File Name                       : Inhambu.jpg
Directory                       : .
File Size                       : 49 kB
File Modification Date/Time     : 2019:06:01 11:37:04-03:00
File Access Date/Time           : 2019:06:01 11:37:04-03:00
File Inode Change Date/Time     : 2019:06:01 11:37:24-03:00
File Permissions                : rw-r--r--
File Type                       : JPEG
File Type Extension             : jpg
MIME Type                       : image/jpeg
JFIF Version                    : 1.01
Resolution Unit                 : inches
X Resolution                    : 96
Y Resolution                    : 96
Image Width                     : 917
Image Height                    : 665
Encoding Process                : Baseline DCT, Huffman coding
Bits Per Sample                 : 8
Color Components                : 3
Y Cb Cr Sub Sampling            : YCbCr4:2:0 (2 2)
Image Size                      : 917x665
Megapixels                      : 0.610

$ exiftool Inhambu.png
ExifTool Version Number         : 10.80
File Name                       : Inhambu.png
Directory                       : .
File Size                       : 47 kB
File Modification Date/Time     : 2019:06:01 11:37:04-03:00
File Access Date/Time           : 2019:06:01 11:37:04-03:00
File Inode Change Date/Time     : 2019:06:01 11:37:44-03:00
File Permissions                : rw-r--r--
File Type                       : PNG
File Type Extension             : png
MIME Type                       : image/png
Image Width                     : 954
Image Height                    : 652
Bit Depth                       : 8
Color Type                      : RGB with Alpha
Compression                     : Deflate/Inflate
Filter                          : Adaptive
Interlace                       : Noninterlaced
Significant Bits                : 8 8 8 8
Pixels Per Unit X               : 3780
Pixels Per Unit Y               : 3780
Pixel Units                     : meters
Image Size                      : 954x652
Megapixels                      : 0.622

  If you save as geotiff the positioning information should be written
in metadata.  I don't know about the PDF format.  In any case, all
informations, except the CRS, will be written to the world file.

  HTH


> Thank you, first time posting, very much appreciate QGIS and its
> community!








  Roxo

--
---------------- Non luctari, ludare -------------------+ WYSIWYG
Fernando M. Roxo da Motta <[hidden email]>              | Editor?
Except where explicitly stated I speak on my own behalf.|  VI !!
                PU5RXO                                  | I see text,
------------ Quis custodiet ipsos custodes?-------------+ I get text!
 
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Re: Is location info included in metadata when save an image file?

Ert Four
Thank you Alex and Roxo for your replies.

From what I can tell the SVG and JPG files probably don't have location info in them, but it's also hard to tell what exactly the data is in some places, especially in the SVG.  

It looks like qgsmaprenderertask.cpp was written two years ago, which was after 2.14 came out.  

I will post on the developer list per Alex's suggestion. All of this is trying to prove that something doesn't exist -- which is always hard.

Thanks again.


> On June 1, 2019 at 4:41 PM "Fernando M. Roxo da Motta" <[hidden email]> wrote:
>
>
> On Thu, 30 May 2019 17:09:59 +0200 (CEST), Ert Four <[hidden email]>
> wrote:
>
>
> > Does any coordinate or location data get embedded in the image file
> > if I use Project > Save as Image or Composer > Export as
> > Image/PDF/SVG?
> >
> > I'm using QGIS version 2.14.3 Essen, although I would like to know
> > about more recent versions, too, for when I upgrade later.
> >
> > (I'm aware of the option to check "World file on" and create a
> > separate world file. What I need is to make sure there is no
> > identifying info whatsoever from the project file in the image file
> > itself.)
> >
> > Eg, say I have a basemap like OpenStreetMap open for a country and I
> > load points in another layer that are inside that country. Then I
> > zoom in on a group of points from my data layer, I turn off the
> > basemap layer, and make a map with just my data points. I want to
> > preserve the relative spatial relationships between my points but not
> > reveal where in the world the map came from. If I publish this image
> > file, might the metadata reveal the location?
> >
> > For the work we do, it's critically important we not unknowingly
> > publish specific locations.
> >
>
>   AFAIK, if you save in PNG or JPEG format no coordinate information is
> stored in metadata of the image:
>
> $ exiftool Inhambu.jpg
> ExifTool Version Number         : 10.80
> File Name                       : Inhambu.jpg
> Directory                       : .
> File Size                       : 49 kB
> File Modification Date/Time     : 2019:06:01 11:37:04-03:00
> File Access Date/Time           : 2019:06:01 11:37:04-03:00
> File Inode Change Date/Time     : 2019:06:01 11:37:24-03:00
> File Permissions                : rw-r--r--
> File Type                       : JPEG
> File Type Extension             : jpg
> MIME Type                       : image/jpeg
> JFIF Version                    : 1.01
> Resolution Unit                 : inches
> X Resolution                    : 96
> Y Resolution                    : 96
> Image Width                     : 917
> Image Height                    : 665
> Encoding Process                : Baseline DCT, Huffman coding
> Bits Per Sample                 : 8
> Color Components                : 3
> Y Cb Cr Sub Sampling            : YCbCr4:2:0 (2 2)
> Image Size                      : 917x665
> Megapixels                      : 0.610
>
> $ exiftool Inhambu.png
> ExifTool Version Number         : 10.80
> File Name                       : Inhambu.png
> Directory                       : .
> File Size                       : 47 kB
> File Modification Date/Time     : 2019:06:01 11:37:04-03:00
> File Access Date/Time           : 2019:06:01 11:37:04-03:00
> File Inode Change Date/Time     : 2019:06:01 11:37:44-03:00
> File Permissions                : rw-r--r--
> File Type                       : PNG
> File Type Extension             : png
> MIME Type                       : image/png
> Image Width                     : 954
> Image Height                    : 652
> Bit Depth                       : 8
> Color Type                      : RGB with Alpha
> Compression                     : Deflate/Inflate
> Filter                          : Adaptive
> Interlace                       : Noninterlaced
> Significant Bits                : 8 8 8 8
> Pixels Per Unit X               : 3780
> Pixels Per Unit Y               : 3780
> Pixel Units                     : meters
> Image Size                      : 954x652
> Megapixels                      : 0.622
>
>   If you save as geotiff the positioning information should be written
> in metadata.  I don't know about the PDF format.  In any case, all
> informations, except the CRS, will be written to the world file.
>
>   HTH
>
>
> > Thank you, first time posting, very much appreciate QGIS and its
> > community!
>
>
>
>
>
>
>
>
>   Roxo
>
> --
> ---------------- Non luctari, ludare -------------------+ WYSIWYG
> Fernando M. Roxo da Motta <[hidden email]>              | Editor?
> Except where explicitly stated I speak on my own behalf.|  VI !!
>                 PU5RXO                                  | I see text,
> ------------ Quis custodiet ipsos custodes?-------------+ I get text!
>  
> _______________________________________________
> Qgis-user mailing list
> [hidden email]
> List info: https://lists.osgeo.org/mailman/listinfo/qgis-user
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Re: Is location info included in metadata when save an image file?

Ert Four
FYI, an update on this. I asked this question to the qgis developer list and Nyall Dawson indicated most image files will have location information embedded in them, here's what he wrote:

----
yes - regardless of that setting, the outputs are georeferenced and have coordinates baked in*

(* depending on format support. SVG doesn't, certain raster formats may not -- check with GDAL whether embedded georeferencing of these is possible. It is for all the common ones at least).
----

Here is the complete original message:
https://lists.osgeo.org/pipermail/qgis-developer/2019-June/057521.html

> On June 2, 2019 at 9:26 AM Ert Four <[hidden email]> wrote:
>
>
> Thank you Alex and Roxo for your replies.
>
> From what I can tell the SVG and JPG files probably don't have location info in them, but it's also hard to tell what exactly the data is in some places, especially in the SVG.  
>
> It looks like qgsmaprenderertask.cpp was written two years ago, which was after 2.14 came out.  
>
> I will post on the developer list per Alex's suggestion. All of this is trying to prove that something doesn't exist -- which is always hard.
>
> Thanks again.
>
>
> > On June 1, 2019 at 4:41 PM "Fernando M. Roxo da Motta" <[hidden email]> wrote:
> >
> >
> > On Thu, 30 May 2019 17:09:59 +0200 (CEST), Ert Four <[hidden email]>
> > wrote:
> >
> >
> > > Does any coordinate or location data get embedded in the image file
> > > if I use Project > Save as Image or Composer > Export as
> > > Image/PDF/SVG?
> > >
> > > I'm using QGIS version 2.14.3 Essen, although I would like to know
> > > about more recent versions, too, for when I upgrade later.
> > >
> > > (I'm aware of the option to check "World file on" and create a
> > > separate world file. What I need is to make sure there is no
> > > identifying info whatsoever from the project file in the image file
> > > itself.)
> > >
> > > Eg, say I have a basemap like OpenStreetMap open for a country and I
> > > load points in another layer that are inside that country. Then I
> > > zoom in on a group of points from my data layer, I turn off the
> > > basemap layer, and make a map with just my data points. I want to
> > > preserve the relative spatial relationships between my points but not
> > > reveal where in the world the map came from. If I publish this image
> > > file, might the metadata reveal the location?
> > >
> > > For the work we do, it's critically important we not unknowingly
> > > publish specific locations.
> > >
> >
> >   AFAIK, if you save in PNG or JPEG format no coordinate information is
> > stored in metadata of the image:
> >
> > $ exiftool Inhambu.jpg
> > ExifTool Version Number         : 10.80
> > File Name                       : Inhambu.jpg
> > Directory                       : .
> > File Size                       : 49 kB
> > File Modification Date/Time     : 2019:06:01 11:37:04-03:00
> > File Access Date/Time           : 2019:06:01 11:37:04-03:00
> > File Inode Change Date/Time     : 2019:06:01 11:37:24-03:00
> > File Permissions                : rw-r--r--
> > File Type                       : JPEG
> > File Type Extension             : jpg
> > MIME Type                       : image/jpeg
> > JFIF Version                    : 1.01
> > Resolution Unit                 : inches
> > X Resolution                    : 96
> > Y Resolution                    : 96
> > Image Width                     : 917
> > Image Height                    : 665
> > Encoding Process                : Baseline DCT, Huffman coding
> > Bits Per Sample                 : 8
> > Color Components                : 3
> > Y Cb Cr Sub Sampling            : YCbCr4:2:0 (2 2)
> > Image Size                      : 917x665
> > Megapixels                      : 0.610
> >
> > $ exiftool Inhambu.png
> > ExifTool Version Number         : 10.80
> > File Name                       : Inhambu.png
> > Directory                       : .
> > File Size                       : 47 kB
> > File Modification Date/Time     : 2019:06:01 11:37:04-03:00
> > File Access Date/Time           : 2019:06:01 11:37:04-03:00
> > File Inode Change Date/Time     : 2019:06:01 11:37:44-03:00
> > File Permissions                : rw-r--r--
> > File Type                       : PNG
> > File Type Extension             : png
> > MIME Type                       : image/png
> > Image Width                     : 954
> > Image Height                    : 652
> > Bit Depth                       : 8
> > Color Type                      : RGB with Alpha
> > Compression                     : Deflate/Inflate
> > Filter                          : Adaptive
> > Interlace                       : Noninterlaced
> > Significant Bits                : 8 8 8 8
> > Pixels Per Unit X               : 3780
> > Pixels Per Unit Y               : 3780
> > Pixel Units                     : meters
> > Image Size                      : 954x652
> > Megapixels                      : 0.622
> >
> >   If you save as geotiff the positioning information should be written
> > in metadata.  I don't know about the PDF format.  In any case, all
> > informations, except the CRS, will be written to the world file.
> >
> >   HTH
> >
> >
> > > Thank you, first time posting, very much appreciate QGIS and its
> > > community!
> >
> >
> >
> >
> >
> >
> >
> >
> >   Roxo
> >
> > --
> > ---------------- Non luctari, ludare -------------------+ WYSIWYG
> > Fernando M. Roxo da Motta <[hidden email]>              | Editor?
> > Except where explicitly stated I speak on my own behalf.|  VI !!
> >                 PU5RXO                                  | I see text,
> > ------------ Quis custodiet ipsos custodes?-------------+ I get text!
> >  
> > _______________________________________________
> > Qgis-user mailing list
> > [hidden email]
> > List info: https://lists.osgeo.org/mailman/listinfo/qgis-user
> > Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-user
> _______________________________________________
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Re: Is location info included in metadata when save an image file?

Kirk Schmidt
In reply to this post by Ert Four
Hi Ert:

You can save locational data in jpg and pdf files from within the Print
Composer window.  Under composition tab on the right hand side of the
window, scroll down and check the Save World File checkbox.  Export your
map/composition as a jpg or pdf and the geolocation data will be written
to a world file for a jpg and internally for a pdf.

Good luck

Kirk Schmidt

On 6/2/2019 4:26 AM, Ert Four wrote:

> Thank you Alex and Roxo for your replies.
>
>  From what I can tell the SVG and JPG files probably don't have location info in them, but it's also hard to tell what exactly the data is in some places, especially in the SVG.
>
> It looks like qgsmaprenderertask.cpp was written two years ago, which was after 2.14 came out.
>
> I will post on the developer list per Alex's suggestion. All of this is trying to prove that something doesn't exist -- which is always hard.
>
> Thanks again.
>
>
>> On June 1, 2019 at 4:41 PM "Fernando M. Roxo da Motta" <[hidden email]> wrote:
>>
>>
>> On Thu, 30 May 2019 17:09:59 +0200 (CEST), Ert Four <[hidden email]>
>> wrote:
>>
>>
>>> Does any coordinate or location data get embedded in the image file
>>> if I use Project > Save as Image or Composer > Export as
>>> Image/PDF/SVG?
>>>
>>> I'm using QGIS version 2.14.3 Essen, although I would like to know
>>> about more recent versions, too, for when I upgrade later.
>>>
>>> (I'm aware of the option to check "World file on" and create a
>>> separate world file. What I need is to make sure there is no
>>> identifying info whatsoever from the project file in the image file
>>> itself.)
>>>
>>> Eg, say I have a basemap like OpenStreetMap open for a country and I
>>> load points in another layer that are inside that country. Then I
>>> zoom in on a group of points from my data layer, I turn off the
>>> basemap layer, and make a map with just my data points. I want to
>>> preserve the relative spatial relationships between my points but not
>>> reveal where in the world the map came from. If I publish this image
>>> file, might the metadata reveal the location?
>>>
>>> For the work we do, it's critically important we not unknowingly
>>> publish specific locations.
>>>
>>    AFAIK, if you save in PNG or JPEG format no coordinate information is
>> stored in metadata of the image:
>>
>> $ exiftool Inhambu.jpg
>> ExifTool Version Number         : 10.80
>> File Name                       : Inhambu.jpg
>> Directory                       : .
>> File Size                       : 49 kB
>> File Modification Date/Time     : 2019:06:01 11:37:04-03:00
>> File Access Date/Time           : 2019:06:01 11:37:04-03:00
>> File Inode Change Date/Time     : 2019:06:01 11:37:24-03:00
>> File Permissions                : rw-r--r--
>> File Type                       : JPEG
>> File Type Extension             : jpg
>> MIME Type                       : image/jpeg
>> JFIF Version                    : 1.01
>> Resolution Unit                 : inches
>> X Resolution                    : 96
>> Y Resolution                    : 96
>> Image Width                     : 917
>> Image Height                    : 665
>> Encoding Process                : Baseline DCT, Huffman coding
>> Bits Per Sample                 : 8
>> Color Components                : 3
>> Y Cb Cr Sub Sampling            : YCbCr4:2:0 (2 2)
>> Image Size                      : 917x665
>> Megapixels                      : 0.610
>>
>> $ exiftool Inhambu.png
>> ExifTool Version Number         : 10.80
>> File Name                       : Inhambu.png
>> Directory                       : .
>> File Size                       : 47 kB
>> File Modification Date/Time     : 2019:06:01 11:37:04-03:00
>> File Access Date/Time           : 2019:06:01 11:37:04-03:00
>> File Inode Change Date/Time     : 2019:06:01 11:37:44-03:00
>> File Permissions                : rw-r--r--
>> File Type                       : PNG
>> File Type Extension             : png
>> MIME Type                       : image/png
>> Image Width                     : 954
>> Image Height                    : 652
>> Bit Depth                       : 8
>> Color Type                      : RGB with Alpha
>> Compression                     : Deflate/Inflate
>> Filter                          : Adaptive
>> Interlace                       : Noninterlaced
>> Significant Bits                : 8 8 8 8
>> Pixels Per Unit X               : 3780
>> Pixels Per Unit Y               : 3780
>> Pixel Units                     : meters
>> Image Size                      : 954x652
>> Megapixels                      : 0.622
>>
>>    If you save as geotiff the positioning information should be written
>> in metadata.  I don't know about the PDF format.  In any case, all
>> informations, except the CRS, will be written to the world file.
>>
>>    HTH
>>
>>
>>> Thank you, first time posting, very much appreciate QGIS and its
>>> community!
>>
>>
>>
>>
>>
>>
>>
>>    Roxo
>>
>> --
>> ---------------- Non luctari, ludare -------------------+ WYSIWYG
>> Fernando M. Roxo da Motta <[hidden email]>              | Editor?
>> Except where explicitly stated I speak on my own behalf.|  VI !!
>>                  PU5RXO                                  | I see text,
>> ------------ Quis custodiet ipsos custodes?-------------+ I get text!
>>  
>> _______________________________________________
>> Qgis-user mailing list
>> [hidden email]
>> List info: https://lists.osgeo.org/mailman/listinfo/qgis-user
>> Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-user
> _______________________________________________
> Qgis-user mailing list
> [hidden email]
> List info: https://lists.osgeo.org/mailman/listinfo/qgis-user
> Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-user

--
Kirk Schmidt, MScF, BScF, RPF
General Manager
Nortek Resource Solutions Inc.
RR # 1
Thorburn, NS
B0K 1W0
Tel (902) 922.3607
Email: [hidden email]
Web: www.nortekresources.com

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Re: Is location info included in metadata when save an image file?

Fernando M. Roxo da Motta
On Mon, 3 Jun 2019 11:01:06 -0300, Kirk Schmidt
<[hidden email]> wrote:


> Hi Ert:
>
> You can save locational data in jpg and pdf files from within the
> Print Composer window.  Under composition tab on the right hand side
> of the window, scroll down and check the Save World File checkbox.
> Export your map/composition as a jpg or pdf and the geolocation data
> will be written to a world file for a jpg and internally for a pdf.

  Just to be sure that I understood it correctly.   If I save as jpg
the geolocation information will be only written to the world file if I
check the Save World File checkbox.   That means that, regardless to
check or not that checkbox, the jpg image will not contain any
geolocation information.

  Is that correct?


>
> Good luck
>
> Kirk Schmidt
>
> On 6/2/2019 4:26 AM, Ert Four wrote:
> > Thank you Alex and Roxo for your replies.
> >
> >  From what I can tell the SVG and JPG files probably don't have
> > location info in them, but it's also hard to tell what exactly the
> > data is in some places, especially in the SVG.
> >
> > It looks like qgsmaprenderertask.cpp was written two years ago,
> > which was after 2.14 came out.
> >
> > I will post on the developer list per Alex's suggestion. All of
> > this is trying to prove that something doesn't exist -- which is
> > always hard.
> >
> > Thanks again.
> >
> >  
> >> On June 1, 2019 at 4:41 PM "Fernando M. Roxo da Motta"
> >> <[hidden email]> wrote:
> >>
> >>
> >> On Thu, 30 May 2019 17:09:59 +0200 (CEST), Ert Four
> >> <[hidden email]> wrote:
> >>
> >>  
> >>> Does any coordinate or location data get embedded in the image
> >>> file if I use Project > Save as Image or Composer > Export as
> >>> Image/PDF/SVG?
> >>>
> >>> I'm using QGIS version 2.14.3 Essen, although I would like to know
> >>> about more recent versions, too, for when I upgrade later.
> >>>
> >>> (I'm aware of the option to check "World file on" and create a
> >>> separate world file. What I need is to make sure there is no
> >>> identifying info whatsoever from the project file in the image
> >>> file itself.)
> >>>
> >>> Eg, say I have a basemap like OpenStreetMap open for a country
> >>> and I load points in another layer that are inside that country.
> >>> Then I zoom in on a group of points from my data layer, I turn
> >>> off the basemap layer, and make a map with just my data points. I
> >>> want to preserve the relative spatial relationships between my
> >>> points but not reveal where in the world the map came from. If I
> >>> publish this image file, might the metadata reveal the location?
> >>>
> >>> For the work we do, it's critically important we not unknowingly
> >>> publish specific locations.
> >>>  
> >>    AFAIK, if you save in PNG or JPEG format no coordinate
> >> information is stored in metadata of the image:
> >>
> >> $ exiftool Inhambu.jpg
> >> ExifTool Version Number         : 10.80
> >> File Name                       : Inhambu.jpg
> >> Directory                       : .
> >> File Size                       : 49 kB
> >> File Modification Date/Time     : 2019:06:01 11:37:04-03:00
> >> File Access Date/Time           : 2019:06:01 11:37:04-03:00
> >> File Inode Change Date/Time     : 2019:06:01 11:37:24-03:00
> >> File Permissions                : rw-r--r--
> >> File Type                       : JPEG
> >> File Type Extension             : jpg
> >> MIME Type                       : image/jpeg
> >> JFIF Version                    : 1.01
> >> Resolution Unit                 : inches
> >> X Resolution                    : 96
> >> Y Resolution                    : 96
> >> Image Width                     : 917
> >> Image Height                    : 665
> >> Encoding Process                : Baseline DCT, Huffman coding
> >> Bits Per Sample                 : 8
> >> Color Components                : 3
> >> Y Cb Cr Sub Sampling            : YCbCr4:2:0 (2 2)
> >> Image Size                      : 917x665
> >> Megapixels                      : 0.610
> >>
> >> $ exiftool Inhambu.png
> >> ExifTool Version Number         : 10.80
> >> File Name                       : Inhambu.png
> >> Directory                       : .
> >> File Size                       : 47 kB
> >> File Modification Date/Time     : 2019:06:01 11:37:04-03:00
> >> File Access Date/Time           : 2019:06:01 11:37:04-03:00
> >> File Inode Change Date/Time     : 2019:06:01 11:37:44-03:00
> >> File Permissions                : rw-r--r--
> >> File Type                       : PNG
> >> File Type Extension             : png
> >> MIME Type                       : image/png
> >> Image Width                     : 954
> >> Image Height                    : 652
> >> Bit Depth                       : 8
> >> Color Type                      : RGB with Alpha
> >> Compression                     : Deflate/Inflate
> >> Filter                          : Adaptive
> >> Interlace                       : Noninterlaced
> >> Significant Bits                : 8 8 8 8
> >> Pixels Per Unit X               : 3780
> >> Pixels Per Unit Y               : 3780
> >> Pixel Units                     : meters
> >> Image Size                      : 954x652
> >> Megapixels                      : 0.622
> >>
> >>    If you save as geotiff the positioning information should be
> >> written in metadata.  I don't know about the PDF format.  In any
> >> case, all informations, except the CRS, will be written to the
> >> world file.
> >>
> >>    HTH
> >>
> >>  
> >>> Thank you, first time posting, very much appreciate QGIS and its
> >>> community!  
> >>
> >>
> >>
> >>
> >>
> >>
> >>
> >>    Roxo
> >>
> >> --
> >> ---------------- Non luctari, ludare -------------------+ WYSIWYG
> >> Fernando M. Roxo da Motta <[hidden email]>              | Editor?
> >> Except where explicitly stated I speak on my own behalf.|  VI !!
> >>                  PU5RXO                                  | I see
> >> text, ------------ Quis custodiet ipsos custodes?-------------+ I
> >> get text!
> >> _______________________________________________
> >> Qgis-user mailing list
> >> [hidden email]
> >> List info: https://lists.osgeo.org/mailman/listinfo/qgis-user
> >> Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-user 
> > _______________________________________________
> > Qgis-user mailing list
> > [hidden email]
> > List info: https://lists.osgeo.org/mailman/listinfo/qgis-user
> > Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-user 
>








  Roxo

--
---------------- Non luctari, ludare -------------------+ WYSIWYG
Fernando M. Roxo da Motta <[hidden email]>              | Editor?
Except where explicitly stated I speak on my own behalf.|  VI !!
                PU5RXO                                  | I see text,
------------ Quis custodiet ipsos custodes?-------------+ I get text!
 
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Re: Is location info included in metadata when save an image file?

Nyall Dawson
On Tue, 4 Jun 2019 at 09:13, Fernando M. Roxo da Motta <[hidden email]> wrote:

>
> On Mon, 3 Jun 2019 11:01:06 -0300, Kirk Schmidt
> <[hidden email]> wrote:
>
>
> > Hi Ert:
> >
> > You can save locational data in jpg and pdf files from within the
> > Print Composer window.  Under composition tab on the right hand side
> > of the window, scroll down and check the Save World File checkbox.
> > Export your map/composition as a jpg or pdf and the geolocation data
> > will be written to a world file for a jpg and internally for a pdf.
>
>   Just to be sure that I understood it correctly.   If I save as jpg
> the geolocation information will be only written to the world file if I
> check the Save World File checkbox.   That means that, regardless to
> check or not that checkbox, the jpg image will not contain any
> geolocation information.
>
>   Is that correct?

Incorrect. It will always be embedded directly inside the image
metadata where possible. The "create world file" checkbox only
controls whether an external text file with the referencing
information is also created.

Nyall

>
>
> >
> > Good luck
> >
> > Kirk Schmidt
> >
> > On 6/2/2019 4:26 AM, Ert Four wrote:
> > > Thank you Alex and Roxo for your replies.
> > >
> > >  From what I can tell the SVG and JPG files probably don't have
> > > location info in them, but it's also hard to tell what exactly the
> > > data is in some places, especially in the SVG.
> > >
> > > It looks like qgsmaprenderertask.cpp was written two years ago,
> > > which was after 2.14 came out.
> > >
> > > I will post on the developer list per Alex's suggestion. All of
> > > this is trying to prove that something doesn't exist -- which is
> > > always hard.
> > >
> > > Thanks again.
> > >
> > >
> > >> On June 1, 2019 at 4:41 PM "Fernando M. Roxo da Motta"
> > >> <[hidden email]> wrote:
> > >>
> > >>
> > >> On Thu, 30 May 2019 17:09:59 +0200 (CEST), Ert Four
> > >> <[hidden email]> wrote:
> > >>
> > >>
> > >>> Does any coordinate or location data get embedded in the image
> > >>> file if I use Project > Save as Image or Composer > Export as
> > >>> Image/PDF/SVG?
> > >>>
> > >>> I'm using QGIS version 2.14.3 Essen, although I would like to know
> > >>> about more recent versions, too, for when I upgrade later.
> > >>>
> > >>> (I'm aware of the option to check "World file on" and create a
> > >>> separate world file. What I need is to make sure there is no
> > >>> identifying info whatsoever from the project file in the image
> > >>> file itself.)
> > >>>
> > >>> Eg, say I have a basemap like OpenStreetMap open for a country
> > >>> and I load points in another layer that are inside that country.
> > >>> Then I zoom in on a group of points from my data layer, I turn
> > >>> off the basemap layer, and make a map with just my data points. I
> > >>> want to preserve the relative spatial relationships between my
> > >>> points but not reveal where in the world the map came from. If I
> > >>> publish this image file, might the metadata reveal the location?
> > >>>
> > >>> For the work we do, it's critically important we not unknowingly
> > >>> publish specific locations.
> > >>>
> > >>    AFAIK, if you save in PNG or JPEG format no coordinate
> > >> information is stored in metadata of the image:
> > >>
> > >> $ exiftool Inhambu.jpg
> > >> ExifTool Version Number         : 10.80
> > >> File Name                       : Inhambu.jpg
> > >> Directory                       : .
> > >> File Size                       : 49 kB
> > >> File Modification Date/Time     : 2019:06:01 11:37:04-03:00
> > >> File Access Date/Time           : 2019:06:01 11:37:04-03:00
> > >> File Inode Change Date/Time     : 2019:06:01 11:37:24-03:00
> > >> File Permissions                : rw-r--r--
> > >> File Type                       : JPEG
> > >> File Type Extension             : jpg
> > >> MIME Type                       : image/jpeg
> > >> JFIF Version                    : 1.01
> > >> Resolution Unit                 : inches
> > >> X Resolution                    : 96
> > >> Y Resolution                    : 96
> > >> Image Width                     : 917
> > >> Image Height                    : 665
> > >> Encoding Process                : Baseline DCT, Huffman coding
> > >> Bits Per Sample                 : 8
> > >> Color Components                : 3
> > >> Y Cb Cr Sub Sampling            : YCbCr4:2:0 (2 2)
> > >> Image Size                      : 917x665
> > >> Megapixels                      : 0.610
> > >>
> > >> $ exiftool Inhambu.png
> > >> ExifTool Version Number         : 10.80
> > >> File Name                       : Inhambu.png
> > >> Directory                       : .
> > >> File Size                       : 47 kB
> > >> File Modification Date/Time     : 2019:06:01 11:37:04-03:00
> > >> File Access Date/Time           : 2019:06:01 11:37:04-03:00
> > >> File Inode Change Date/Time     : 2019:06:01 11:37:44-03:00
> > >> File Permissions                : rw-r--r--
> > >> File Type                       : PNG
> > >> File Type Extension             : png
> > >> MIME Type                       : image/png
> > >> Image Width                     : 954
> > >> Image Height                    : 652
> > >> Bit Depth                       : 8
> > >> Color Type                      : RGB with Alpha
> > >> Compression                     : Deflate/Inflate
> > >> Filter                          : Adaptive
> > >> Interlace                       : Noninterlaced
> > >> Significant Bits                : 8 8 8 8
> > >> Pixels Per Unit X               : 3780
> > >> Pixels Per Unit Y               : 3780
> > >> Pixel Units                     : meters
> > >> Image Size                      : 954x652
> > >> Megapixels                      : 0.622
> > >>
> > >>    If you save as geotiff the positioning information should be
> > >> written in metadata.  I don't know about the PDF format.  In any
> > >> case, all informations, except the CRS, will be written to the
> > >> world file.
> > >>
> > >>    HTH
> > >>
> > >>
> > >>> Thank you, first time posting, very much appreciate QGIS and its
> > >>> community!
> > >>
> > >>
> > >>
> > >>
> > >>
> > >>
> > >>
> > >>    Roxo
> > >>
> > >> --
> > >> ---------------- Non luctari, ludare -------------------+ WYSIWYG
> > >> Fernando M. Roxo da Motta <[hidden email]>              | Editor?
> > >> Except where explicitly stated I speak on my own behalf.|  VI !!
> > >>                  PU5RXO                                  | I see
> > >> text, ------------ Quis custodiet ipsos custodes?-------------+ I
> > >> get text!
> > >> _______________________________________________
> > >> Qgis-user mailing list
> > >> [hidden email]
> > >> List info: https://lists.osgeo.org/mailman/listinfo/qgis-user
> > >> Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-user
> > > _______________________________________________
> > > Qgis-user mailing list
> > > [hidden email]
> > > List info: https://lists.osgeo.org/mailman/listinfo/qgis-user
> > > Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-user
> >
>
>
>
>
>
>
>
>
>   Roxo
>
> --
> ---------------- Non luctari, ludare -------------------+ WYSIWYG
> Fernando M. Roxo da Motta <[hidden email]>              | Editor?
> Except where explicitly stated I speak on my own behalf.|  VI !!
>                 PU5RXO                                  | I see text,
> ------------ Quis custodiet ipsos custodes?-------------+ I get text!
>
> _______________________________________________
> Qgis-user mailing list
> [hidden email]
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Re: Is location info included in metadata when save an image file?

Brent Wood-7
In reply to this post by Fernando M. Roxo da Motta


JPG images can only store a gps location internally, not the geographic extent of the image.

TIFF is the only conventional raster image format which supports internal geographic extent metadata.


Brent Wood

Programme leader: Environmental Information Delivery
NIWA
DDI:  +64 (4) 3860529





Brent Wood
Principal Technician - GIS and Spatial Data Management
Programme Leader - Environmental Information Delivery
T +64-4-386-0529  
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________________________________________
From: Qgis-user <[hidden email]> on behalf of Fernando M. Roxo da Motta <[hidden email]>
Sent: Tuesday, June 4, 2019 11:13
To: [hidden email]
Subject: Re: [Qgis-user] Is location info included in metadata when save an image file?

On Mon, 3 Jun 2019 11:01:06 -0300, Kirk Schmidt
<[hidden email]> wrote:


> Hi Ert:
>
> You can save locational data in jpg and pdf files from within the
> Print Composer window.  Under composition tab on the right hand side
> of the window, scroll down and check the Save World File checkbox.
> Export your map/composition as a jpg or pdf and the geolocation data
> will be written to a world file for a jpg and internally for a pdf.

 Just to be sure that I understood it correctly.   If I save as jpg
the geolocation information will be only written to the world file if I
check the Save World File checkbox.   That means that, regardless to
check or not that checkbox, the jpg image will not contain any
geolocation information.

 Is that correct?


>
> Good luck
>
> Kirk Schmidt
>
> On 6/2/2019 4:26 AM, Ert Four wrote:
> > Thank you Alex and Roxo for your replies.
> >
> >  From what I can tell the SVG and JPG files probably don't have
> > location info in them, but it's also hard to tell what exactly the
> > data is in some places, especially in the SVG.
> >
> > It looks like qgsmaprenderertask.cpp was written two years ago,
> > which was after 2.14 came out.
> >
> > I will post on the developer list per Alex's suggestion. All of
> > this is trying to prove that something doesn't exist -- which is
> > always hard.
> >
> > Thanks again.
> >
> >
> >> On June 1, 2019 at 4:41 PM "Fernando M. Roxo da Motta"
> >> <[hidden email]> wrote:
> >>
> >>
> >> On Thu, 30 May 2019 17:09:59 +0200 (CEST), Ert Four
> >> <[hidden email]> wrote:
> >>
> >>
> >>> Does any coordinate or location data get embedded in the image
> >>> file if I use Project > Save as Image or Composer > Export as
> >>> Image/PDF/SVG?
> >>>
> >>> I'm using QGIS version 2.14.3 Essen, although I would like to know
> >>> about more recent versions, too, for when I upgrade later.
> >>>
> >>> (I'm aware of the option to check "World file on" and create a
> >>> separate world file. What I need is to make sure there is no
> >>> identifying info whatsoever from the project file in the image
> >>> file itself.)
> >>>
> >>> Eg, say I have a basemap like OpenStreetMap open for a country
> >>> and I load points in another layer that are inside that country.
> >>> Then I zoom in on a group of points from my data layer, I turn
> >>> off the basemap layer, and make a map with just my data points. I
> >>> want to preserve the relative spatial relationships between my
> >>> points but not reveal where in the world the map came from. If I
> >>> publish this image file, might the metadata reveal the location?
> >>>
> >>> For the work we do, it's critically important we not unknowingly
> >>> publish specific locations.
> >>>
> >>    AFAIK, if you save in PNG or JPEG format no coordinate
> >> information is stored in metadata of the image:
> >>
> >> $ exiftool Inhambu.jpg
> >> ExifTool Version Number         : 10.80
> >> File Name                       : Inhambu.jpg
> >> Directory                       : .
> >> File Size                       : 49 kB
> >> File Modification Date/Time     : 2019:06:01 11:37:04-03:00
> >> File Access Date/Time           : 2019:06:01 11:37:04-03:00
> >> File Inode Change Date/Time     : 2019:06:01 11:37:24-03:00
> >> File Permissions                : rw-r--r--
> >> File Type                       : JPEG
> >> File Type Extension             : jpg
> >> MIME Type                       : image/jpeg
> >> JFIF Version                    : 1.01
> >> Resolution Unit                 : inches
> >> X Resolution                    : 96
> >> Y Resolution                    : 96
> >> Image Width                     : 917
> >> Image Height                    : 665
> >> Encoding Process                : Baseline DCT, Huffman coding
> >> Bits Per Sample                 : 8
> >> Color Components                : 3
> >> Y Cb Cr Sub Sampling            : YCbCr4:2:0 (2 2)
> >> Image Size                      : 917x665
> >> Megapixels                      : 0.610
> >>
> >> $ exiftool Inhambu.png
> >> ExifTool Version Number         : 10.80
> >> File Name                       : Inhambu.png
> >> Directory                       : .
> >> File Size                       : 47 kB
> >> File Modification Date/Time     : 2019:06:01 11:37:04-03:00
> >> File Access Date/Time           : 2019:06:01 11:37:04-03:00
> >> File Inode Change Date/Time     : 2019:06:01 11:37:44-03:00
> >> File Permissions                : rw-r--r--
> >> File Type                       : PNG
> >> File Type Extension             : png
> >> MIME Type                       : image/png
> >> Image Width                     : 954
> >> Image Height                    : 652
> >> Bit Depth                       : 8
> >> Color Type                      : RGB with Alpha
> >> Compression                     : Deflate/Inflate
> >> Filter                          : Adaptive
> >> Interlace                       : Noninterlaced
> >> Significant Bits                : 8 8 8 8
> >> Pixels Per Unit X               : 3780
> >> Pixels Per Unit Y               : 3780
> >> Pixel Units                     : meters
> >> Image Size                      : 954x652
> >> Megapixels                      : 0.622
> >>
> >>    If you save as geotiff the positioning information should be
> >> written in metadata.  I don't know about the PDF format.  In any
> >> case, all informations, except the CRS, will be written to the
> >> world file.
> >>
> >>    HTH
> >>
> >>
> >>> Thank you, first time posting, very much appreciate QGIS and its
> >>> community!
> >>
> >>
> >>
> >>
> >>
> >>
> >>
> >>    Roxo
> >>
> >> --
> >> ---------------- Non luctari, ludare -------------------+ WYSIWYG
> >> Fernando M. Roxo da Motta <[hidden email]>              | Editor?
> >> Except where explicitly stated I speak on my own behalf.|  VI !!
> >>                  PU5RXO                                  | I see
> >> text, ------------ Quis custodiet ipsos custodes?-------------+ I
> >> get text!
> >> _______________________________________________
> >> Qgis-user mailing list
> >> [hidden email]
> >> List info: https://lists.osgeo.org/mailman/listinfo/qgis-user
> >> Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-user
> > _______________________________________________
> > Qgis-user mailing list
> > [hidden email]
> > List info: https://lists.osgeo.org/mailman/listinfo/qgis-user
> > Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-user
>








 Roxo

--
---------------- Non luctari, ludare -------------------+ WYSIWYG
Fernando M. Roxo da Motta <[hidden email]>              | Editor?
Except where explicitly stated I speak on my own behalf.|  VI !!
               PU5RXO                                  | I see text,
------------ Quis custodiet ipsos custodes?-------------+ I get text!

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Re: Is location info included in metadata when save an image file?

qgis-user
As a purely empirical experiment -
I exported a map canvas (the OP's goal)  to jpeg with no world file. I
opened a new map and brought in the jpeg as a layer. qgis could NOT
geolocate it. I would think (hope?) that if qgis were writing location
data to the file it would be able to read it.
This result is consistent with the various assertions that there is no
geo-data in a jpeg, as it does not appear in the exif metadata.
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Re: Is location info included in metadata when save an image file?

Alex Mandel-2
In reply to this post by Nyall Dawson
Nyall,

I just did a test like Kirk png and jpg do not contain EXIF coordinates.
For the purposes of this discussion the original poster wants to know
which formats drop the location data, and it appears jpg and png are
safe for that purpose. I would advise that not every format will behave
the same, as we all seem to agree a tiff from the Image Save should have
the location in it's metadata. Though I know a good way to strip that
out - GIMP or Photoshop, open & export usually kills all metadata,
command line Photography tools might also (e.g. imagemagick).

Tested with QGIS 3.4

Thanks,
Alex

On 6/3/19 16:16, Nyall Dawson wrote:

> On Tue, 4 Jun 2019 at 09:13, Fernando M. Roxo da Motta <[hidden email]> wrote:
>>
>> On Mon, 3 Jun 2019 11:01:06 -0300, Kirk Schmidt
>> <[hidden email]> wrote:
>>
>>
>>> Hi Ert:
>>>
>>> You can save locational data in jpg and pdf files from within the
>>> Print Composer window.  Under composition tab on the right hand side
>>> of the window, scroll down and check the Save World File checkbox.
>>> Export your map/composition as a jpg or pdf and the geolocation data
>>> will be written to a world file for a jpg and internally for a pdf.
>>
>>   Just to be sure that I understood it correctly.   If I save as jpg
>> the geolocation information will be only written to the world file if I
>> check the Save World File checkbox.   That means that, regardless to
>> check or not that checkbox, the jpg image will not contain any
>> geolocation information.
>>
>>   Is that correct?
>
> Incorrect. It will always be embedded directly inside the image
> metadata where possible. The "create world file" checkbox only
> controls whether an external text file with the referencing
> information is also created.
>
> Nyall
>
>>
>>
>>>
>>> Good luck
>>>
>>> Kirk Schmidt
>>>
>>> On 6/2/2019 4:26 AM, Ert Four wrote:
>>>> Thank you Alex and Roxo for your replies.
>>>>
>>>>  From what I can tell the SVG and JPG files probably don't have
>>>> location info in them, but it's also hard to tell what exactly the
>>>> data is in some places, especially in the SVG.
>>>>
>>>> It looks like qgsmaprenderertask.cpp was written two years ago,
>>>> which was after 2.14 came out.
>>>>
>>>> I will post on the developer list per Alex's suggestion. All of
>>>> this is trying to prove that something doesn't exist -- which is
>>>> always hard.
>>>>
>>>> Thanks again.
>>>>
>>>>
>>>>> On June 1, 2019 at 4:41 PM "Fernando M. Roxo da Motta"
>>>>> <[hidden email]> wrote:
>>>>>
>>>>>
>>>>> On Thu, 30 May 2019 17:09:59 +0200 (CEST), Ert Four
>>>>> <[hidden email]> wrote:
>>>>>
>>>>>
>>>>>> Does any coordinate or location data get embedded in the image
>>>>>> file if I use Project > Save as Image or Composer > Export as
>>>>>> Image/PDF/SVG?
>>>>>>
>>>>>> I'm using QGIS version 2.14.3 Essen, although I would like to know
>>>>>> about more recent versions, too, for when I upgrade later.
>>>>>>
>>>>>> (I'm aware of the option to check "World file on" and create a
>>>>>> separate world file. What I need is to make sure there is no
>>>>>> identifying info whatsoever from the project file in the image
>>>>>> file itself.)
>>>>>>
>>>>>> Eg, say I have a basemap like OpenStreetMap open for a country
>>>>>> and I load points in another layer that are inside that country.
>>>>>> Then I zoom in on a group of points from my data layer, I turn
>>>>>> off the basemap layer, and make a map with just my data points. I
>>>>>> want to preserve the relative spatial relationships between my
>>>>>> points but not reveal where in the world the map came from. If I
>>>>>> publish this image file, might the metadata reveal the location?
>>>>>>
>>>>>> For the work we do, it's critically important we not unknowingly
>>>>>> publish specific locations.
>>>>>>
>>>>>    AFAIK, if you save in PNG or JPEG format no coordinate
>>>>> information is stored in metadata of the image:
>>>>>
>>>>> $ exiftool Inhambu.jpg
>>>>> ExifTool Version Number         : 10.80
>>>>> File Name                       : Inhambu.jpg
>>>>> Directory                       : .
>>>>> File Size                       : 49 kB
>>>>> File Modification Date/Time     : 2019:06:01 11:37:04-03:00
>>>>> File Access Date/Time           : 2019:06:01 11:37:04-03:00
>>>>> File Inode Change Date/Time     : 2019:06:01 11:37:24-03:00
>>>>> File Permissions                : rw-r--r--
>>>>> File Type                       : JPEG
>>>>> File Type Extension             : jpg
>>>>> MIME Type                       : image/jpeg
>>>>> JFIF Version                    : 1.01
>>>>> Resolution Unit                 : inches
>>>>> X Resolution                    : 96
>>>>> Y Resolution                    : 96
>>>>> Image Width                     : 917
>>>>> Image Height                    : 665
>>>>> Encoding Process                : Baseline DCT, Huffman coding
>>>>> Bits Per Sample                 : 8
>>>>> Color Components                : 3
>>>>> Y Cb Cr Sub Sampling            : YCbCr4:2:0 (2 2)
>>>>> Image Size                      : 917x665
>>>>> Megapixels                      : 0.610
>>>>>
>>>>> $ exiftool Inhambu.png
>>>>> ExifTool Version Number         : 10.80
>>>>> File Name                       : Inhambu.png
>>>>> Directory                       : .
>>>>> File Size                       : 47 kB
>>>>> File Modification Date/Time     : 2019:06:01 11:37:04-03:00
>>>>> File Access Date/Time           : 2019:06:01 11:37:04-03:00
>>>>> File Inode Change Date/Time     : 2019:06:01 11:37:44-03:00
>>>>> File Permissions                : rw-r--r--
>>>>> File Type                       : PNG
>>>>> File Type Extension             : png
>>>>> MIME Type                       : image/png
>>>>> Image Width                     : 954
>>>>> Image Height                    : 652
>>>>> Bit Depth                       : 8
>>>>> Color Type                      : RGB with Alpha
>>>>> Compression                     : Deflate/Inflate
>>>>> Filter                          : Adaptive
>>>>> Interlace                       : Noninterlaced
>>>>> Significant Bits                : 8 8 8 8
>>>>> Pixels Per Unit X               : 3780
>>>>> Pixels Per Unit Y               : 3780
>>>>> Pixel Units                     : meters
>>>>> Image Size                      : 954x652
>>>>> Megapixels                      : 0.622
>>>>>
>>>>>    If you save as geotiff the positioning information should be
>>>>> written in metadata.  I don't know about the PDF format.  In any
>>>>> case, all informations, except the CRS, will be written to the
>>>>> world file.
>>>>>
>>>>>    HTH
>>>>>
>>>>>
>>>>>> Thank you, first time posting, very much appreciate QGIS and its
>>>>>> community!
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>    Roxo
>>>>>
>>>>> --
>>>>> ---------------- Non luctari, ludare -------------------+ WYSIWYG
>>>>> Fernando M. Roxo da Motta <[hidden email]>              | Editor?
>>>>> Except where explicitly stated I speak on my own behalf.|  VI !!
>>>>>                  PU5RXO                                  | I see
>>>>> text, ------------ Quis custodiet ipsos custodes?-------------+ I
>>>>> get text!
>>>>> _______________________________________________
>>>>> Qgis-user mailing list
>>>>> [hidden email]
>>>>> List info: https://lists.osgeo.org/mailman/listinfo/qgis-user
>>>>> Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-user
>>>> _______________________________________________
>>>> Qgis-user mailing list
>>>> [hidden email]
>>>> List info: https://lists.osgeo.org/mailman/listinfo/qgis-user
>>>> Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-user
>>>
>>
>>
>>
>>
>>
>>
>>
>>
>>   Roxo
>>
>> --
>> ---------------- Non luctari, ludare -------------------+ WYSIWYG
>> Fernando M. Roxo da Motta <[hidden email]>              | Editor?
>> Except where explicitly stated I speak on my own behalf.|  VI !!
>>                 PU5RXO                                  | I see text,
>> ------------ Quis custodiet ipsos custodes?-------------+ I get text!
>>
>> _______________________________________________
>> Qgis-user mailing list
>> [hidden email]
>> List info: https://lists.osgeo.org/mailman/listinfo/qgis-user
>> Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-user
> _______________________________________________
> Qgis-user mailing list
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>

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Re: Is location info included in metadata when save an image file?

Kirk Schmidt
Ert:

With a jpg or png file, the coordinate data are stored in the world file
(a simple text file with the pixel x gsd , rotation,pixel y gsd, x
coordinate, top left, y coordinate top left - see sample below).  For a
pdf, the coordinate data is stored within the pdf and you would have to
check the geo-pdf specs to see where they are stored.  If you write a
geotiff, the coordinates will be contained withing the file header.

Sample tiff world file (*.tfw)

0.0250000000
0.000000
0.000000
-0.0250000000
674643.3881379978
4945024.4282323727

Kirk

On 6/4/2019 1:48 PM, Alex M wrote:

> Nyall,
>
> I just did a test like Kirk png and jpg do not contain EXIF coordinates.
> For the purposes of this discussion the original poster wants to know
> which formats drop the location data, and it appears jpg and png are
> safe for that purpose. I would advise that not every format will behave
> the same, as we all seem to agree a tiff from the Image Save should have
> the location in it's metadata. Though I know a good way to strip that
> out - GIMP or Photoshop, open & export usually kills all metadata,
> command line Photography tools might also (e.g. imagemagick).
>
> Tested with QGIS 3.4
>
> Thanks,
> Alex
>
> On 6/3/19 16:16, Nyall Dawson wrote:
>> On Tue, 4 Jun 2019 at 09:13, Fernando M. Roxo da Motta <[hidden email]> wrote:
>>> On Mon, 3 Jun 2019 11:01:06 -0300, Kirk Schmidt
>>> <[hidden email]> wrote:
>>>
>>>
>>>> Hi Ert:
>>>>
>>>> You can save locational data in jpg and pdf files from within the
>>>> Print Composer window.  Under composition tab on the right hand side
>>>> of the window, scroll down and check the Save World File checkbox.
>>>> Export your map/composition as a jpg or pdf and the geolocation data
>>>> will be written to a world file for a jpg and internally for a pdf.
>>>    Just to be sure that I understood it correctly.   If I save as jpg
>>> the geolocation information will be only written to the world file if I
>>> check the Save World File checkbox.   That means that, regardless to
>>> check or not that checkbox, the jpg image will not contain any
>>> geolocation information.
>>>
>>>    Is that correct?
>> Incorrect. It will always be embedded directly inside the image
>> metadata where possible. The "create world file" checkbox only
>> controls whether an external text file with the referencing
>> information is also created.
>>
>> Nyall
>>
>>>
>>>> Good luck
>>>>
>>>> Kirk Schmidt
>>>>
>>>> On 6/2/2019 4:26 AM, Ert Four wrote:
>>>>> Thank you Alex and Roxo for your replies.
>>>>>
>>>>>   From what I can tell the SVG and JPG files probably don't have
>>>>> location info in them, but it's also hard to tell what exactly the
>>>>> data is in some places, especially in the SVG.
>>>>>
>>>>> It looks like qgsmaprenderertask.cpp was written two years ago,
>>>>> which was after 2.14 came out.
>>>>>
>>>>> I will post on the developer list per Alex's suggestion. All of
>>>>> this is trying to prove that something doesn't exist -- which is
>>>>> always hard.
>>>>>
>>>>> Thanks again.
>>>>>
>>>>>
>>>>>> On June 1, 2019 at 4:41 PM "Fernando M. Roxo da Motta"
>>>>>> <[hidden email]> wrote:
>>>>>>
>>>>>>
>>>>>> On Thu, 30 May 2019 17:09:59 +0200 (CEST), Ert Four
>>>>>> <[hidden email]> wrote:
>>>>>>
>>>>>>
>>>>>>> Does any coordinate or location data get embedded in the image
>>>>>>> file if I use Project > Save as Image or Composer > Export as
>>>>>>> Image/PDF/SVG?
>>>>>>>
>>>>>>> I'm using QGIS version 2.14.3 Essen, although I would like to know
>>>>>>> about more recent versions, too, for when I upgrade later.
>>>>>>>
>>>>>>> (I'm aware of the option to check "World file on" and create a
>>>>>>> separate world file. What I need is to make sure there is no
>>>>>>> identifying info whatsoever from the project file in the image
>>>>>>> file itself.)
>>>>>>>
>>>>>>> Eg, say I have a basemap like OpenStreetMap open for a country
>>>>>>> and I load points in another layer that are inside that country.
>>>>>>> Then I zoom in on a group of points from my data layer, I turn
>>>>>>> off the basemap layer, and make a map with just my data points. I
>>>>>>> want to preserve the relative spatial relationships between my
>>>>>>> points but not reveal where in the world the map came from. If I
>>>>>>> publish this image file, might the metadata reveal the location?
>>>>>>>
>>>>>>> For the work we do, it's critically important we not unknowingly
>>>>>>> publish specific locations.
>>>>>>>
>>>>>>     AFAIK, if you save in PNG or JPEG format no coordinate
>>>>>> information is stored in metadata of the image:
>>>>>>
>>>>>> $ exiftool Inhambu.jpg
>>>>>> ExifTool Version Number         : 10.80
>>>>>> File Name                       : Inhambu.jpg
>>>>>> Directory                       : .
>>>>>> File Size                       : 49 kB
>>>>>> File Modification Date/Time     : 2019:06:01 11:37:04-03:00
>>>>>> File Access Date/Time           : 2019:06:01 11:37:04-03:00
>>>>>> File Inode Change Date/Time     : 2019:06:01 11:37:24-03:00
>>>>>> File Permissions                : rw-r--r--
>>>>>> File Type                       : JPEG
>>>>>> File Type Extension             : jpg
>>>>>> MIME Type                       : image/jpeg
>>>>>> JFIF Version                    : 1.01
>>>>>> Resolution Unit                 : inches
>>>>>> X Resolution                    : 96
>>>>>> Y Resolution                    : 96
>>>>>> Image Width                     : 917
>>>>>> Image Height                    : 665
>>>>>> Encoding Process                : Baseline DCT, Huffman coding
>>>>>> Bits Per Sample                 : 8
>>>>>> Color Components                : 3
>>>>>> Y Cb Cr Sub Sampling            : YCbCr4:2:0 (2 2)
>>>>>> Image Size                      : 917x665
>>>>>> Megapixels                      : 0.610
>>>>>>
>>>>>> $ exiftool Inhambu.png
>>>>>> ExifTool Version Number         : 10.80
>>>>>> File Name                       : Inhambu.png
>>>>>> Directory                       : .
>>>>>> File Size                       : 47 kB
>>>>>> File Modification Date/Time     : 2019:06:01 11:37:04-03:00
>>>>>> File Access Date/Time           : 2019:06:01 11:37:04-03:00
>>>>>> File Inode Change Date/Time     : 2019:06:01 11:37:44-03:00
>>>>>> File Permissions                : rw-r--r--
>>>>>> File Type                       : PNG
>>>>>> File Type Extension             : png
>>>>>> MIME Type                       : image/png
>>>>>> Image Width                     : 954
>>>>>> Image Height                    : 652
>>>>>> Bit Depth                       : 8
>>>>>> Color Type                      : RGB with Alpha
>>>>>> Compression                     : Deflate/Inflate
>>>>>> Filter                          : Adaptive
>>>>>> Interlace                       : Noninterlaced
>>>>>> Significant Bits                : 8 8 8 8
>>>>>> Pixels Per Unit X               : 3780
>>>>>> Pixels Per Unit Y               : 3780
>>>>>> Pixel Units                     : meters
>>>>>> Image Size                      : 954x652
>>>>>> Megapixels                      : 0.622
>>>>>>
>>>>>>     If you save as geotiff the positioning information should be
>>>>>> written in metadata.  I don't know about the PDF format.  In any
>>>>>> case, all informations, except the CRS, will be written to the
>>>>>> world file.
>>>>>>
>>>>>>     HTH
>>>>>>
>>>>>>
>>>>>>> Thank you, first time posting, very much appreciate QGIS and its
>>>>>>> community!
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>     Roxo
>>>>>>
>>>>>> --
>>>>>> ---------------- Non luctari, ludare -------------------+ WYSIWYG
>>>>>> Fernando M. Roxo da Motta <[hidden email]>              | Editor?
>>>>>> Except where explicitly stated I speak on my own behalf.|  VI !!
>>>>>>                   PU5RXO                                  | I see
>>>>>> text, ------------ Quis custodiet ipsos custodes?-------------+ I
>>>>>> get text!
>>>>>> _______________________________________________
>>>>>> Qgis-user mailing list
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>>>>>> List info: https://lists.osgeo.org/mailman/listinfo/qgis-user
>>>>>> Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-user
>>>>> _______________________________________________
>>>>> Qgis-user mailing list
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>>>>> List info: https://lists.osgeo.org/mailman/listinfo/qgis-user
>>>>> Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-user
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>    Roxo
>>>
>>> --
>>> ---------------- Non luctari, ludare -------------------+ WYSIWYG
>>> Fernando M. Roxo da Motta <[hidden email]>              | Editor?
>>> Except where explicitly stated I speak on my own behalf.|  VI !!
>>>                  PU5RXO                                  | I see text,
>>> ------------ Quis custodiet ipsos custodes?-------------+ I get text!
>>>
>>> _______________________________________________
>>> Qgis-user mailing list
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--
Kirk Schmidt, MScF, BScF, RPF
General Manager
Nortek Resource Solutions Inc.
RR # 1
Thorburn, NS
B0K 1W0
Tel (902) 922.3607
Email: [hidden email]
Web: www.nortekresources.com

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