[Qgis-user] Is location info included in metadata when save an image file?
Brent Wood
Brent.Wood at niwa.co.nz
Mon Jun 3 16:17:43 PDT 2019
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
[cid:image2643d9.PNG at f79ed398.42a8a704]<http://www.niwa.co.nz>
Brent Wood
Principal Technician - GIS and Spatial Data Management
Programme Leader - Environmental Information Delivery
T +64-4-386-0529
National Institute of Water & Atmospheric Research Ltd (NIWA)
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________________________________________
From: Qgis-user <qgis-user-bounces at lists.osgeo.org> on behalf of Fernando M. Roxo da Motta <petro at roxo.org>
Sent: Tuesday, June 4, 2019 11:13
To: qgis-user at lists.osgeo.org
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
<kirk at nortekresources.com> 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"
> >> <petro at roxo.org> wrote:
> >>
> >>
> >> On Thu, 30 May 2019 17:09:59 +0200 (CEST), Ert Four
> >> <4ert at mailbox.org> 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 <petro at roxo.org> | 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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Roxo
--
---------------- Non luctari, ludare -------------------+ WYSIWYG
Fernando M. Roxo da Motta <petro at roxo.org> | 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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