IPTC fields?

[paul womack]

I often find my self performing pre-processing on
images for Hugin (e.g. combining stacked image with enfuse).

This has the unfortunate effect of dropping all the IPTC
data (depending of which tool I use, netpbm, imagemagick, enfuse, etc),
which means that orientation and exposure data is lost, making
Hugin less convenient.

To avoid this, I could use exiftool to transfer IPTC data from one of the source
images to the output image of my preprocessing, in the same
way that Hugin itself does.

What (IPTC) fields do I need to transfer to get the
best behaviour from Hugin?

BugBear

[Carl von Einem]

Hi BugBear,

paul womack wrote on 06.10.16 10:22:

I think IPTC tries to describe the visual content and provide
information about creator and copyright, see
https://iptc.org/standards/photo-metadata/photo-metadata/

To my understanding the type of information you want to preserve is
usually stored in (and read from) the EXIF metadata fields. However IPTC
and EXIF seem to use some compatible fields, so maybe you'll just need
to adapt your workflow to convert or copy these fields (see below) from
IPTC to EXIF.

My workflow regarding metadata (and a proper file name to begin with)
uses exiftool (try these commands with copies of your images first, they
work for me on Mac OS X)

- rename files using exiftool to get rid of the arbitrary 'img_1234.jpg'
naming scheme like this:
exiftool '-FileName<${CreateDate}_$filenumber.%e' -d
MyPrefix_%Y%m%d-%H%M%S%%-c /Users/youraccount/path/to/photodirectory

- include lon/lat/altitude data from my Garmin's gpx file. I usually use
a different tool on my Mac but this can also be done with exiftool like
this:
exiftool -geotag "/Users/carl/path/to/gpx-files/*.gpx"
/Users/youraccount/path/to/photodirectory

- this command will change the images' modify date but this can be
corrected with:
exiftool '-DateTimeOriginal>FileModifyDate'
/Users/youraccount/path/to/photodirectory


My raw image converter also includes these values with the tiffs that I
import in my Hugin projects. Hugin copies the EXIF values from the first
image into the stitched panorama.

So in one of my finished panoramas I find this EXIF information (amongst
other data):
Copyright : Carl von Einem
Date Created : 2016:08:07
Time Created : 15:06:16+00:00
Date/Time Created : 2016:08:07 15:06:16+00:00
GPS Altitude : 612.8 m Above Sea Level
GPS Latitude : 47 deg 45' 55.13" N
GPS Longitude : 11 deg 9' 52.39" E
GPS Position : 47 deg 45' 55.13" N, 11 deg 9' 52.39" E

Hope that helps,
Carl

[T. Modes]

Am Donnerstag, 6. Oktober 2016 10:23:06 UTC+2 schrieb bugbear:

What (IPTC) fields do I need to transfer to get the
best behaviour from Hugin?

Hugin does not read IPTC fields.
From EXIF it reads exposure time, aperture and ISO for calculation of exposure value. Then the focal length. For crop factor there are several EXIF tags used depending on the camera model (focallength in 35mm, sensor dimension,…). The camera name, camera manufacture and lens name are read from the EXIF tag or from the makernotes and used for lookup in the cam/lens database.
The the orientation tag is read for initial position of portrait images. For the initial white balance is reads some tags from the makernotes.
Furthermore the GPano tags in XMP are evaluated.

[cspiel]

On Thursday, 6 October 2016 10:23:06 UTC+2, bugbear wrote:

This has the unfortunate effect of dropping all the IPTC
data (depending of which tool I use, netpbm, imagemagick, enfuse, etc),
which means that orientation and exposure data is lost, making
Hugin less convenient.

If you just need a trivial copy of EXIF/IPTC/XMP data from Enblend and Enfuse,
I can arrange for that.  If fact, I have a patch to add this functionality to both
applications.  It relies on libexiv2, which is already used by Hugin.

Please let me know what you want/need, like, for example, some tags dropped
or special tags added, command-line options, and so on.

Thanks,
    Chris
 

[bugbear]

T. Modes wrote:
>
>
> Am Donnerstag, 6. Oktober 2016 10:23:06 UTC+2 schrieb bugbear:
>
>
> What (IPTC) fields do I need to transfer to get the
> best behaviour from Hugin?
>
>
> Hugin does not read IPTC fields.

I have now downloaded the source, and done some searching; I think this is a list
of all the Exif and Xmp tags used by Hugin;

"Exif.Photo.ExposureMode"
"Exif.Photo.PixelXDimension"
"Exif.Photo.PixelYDimension"
"Exif.Photo.FocalLengthIn35mmFilm"
"Exif.Photo.DateTimeOriginal"
"Exif.Photo.FocalPlaneResolutionUnit"
"Exif.Photo.FocalPlaneXResolution"
"Exif.Photo.FocalPlaneYResolution"
"Exif.Photo.LensModel"
"Xmp.GPano.ProjectionType"
"Xmp.GPano.CroppedAreaImageWidthPixels"
"Xmp.GPano.CroppedAreaImageHeightPixels"
"Xmp.GPano.FullPanoWidthPixels"
"Xmp.GPano.FullPanoHeightPixels"
"Xmp.GPano.CroppedAreaTopPixels"

BugBear

[T. Modes]

Am Montag, 10. Oktober 2016 11:26:34 UTC+2 schrieb bugbear:

I have now downloaded the source, and done some searching; I think this is a list
of all the Exif and Xmp tags used by Hugin;

This list is far from complete. Some important information are missing. Please reread my last post. I mentioned the important pieces there.

[bugbear]

Your post provided valuable outline guidance, but did not provide actual Tag names
that I can use in Exiftool. If you would care to add the tag names you know about to my list,
I would be very grateful.

BugBear

[T. Modes]

Am Dienstag, 11. Oktober 2016 10:06:13 UTC+2 schrieb bugbear:

Your post provided valuable outline guidance, but did not provide actual Tag names
that I can use in Exiftool. If you would care to add the tag names you know about to my list,
I would be very grateful.

The list would be very long and it would need some work, because some information can be extracted from several tags, depending on the camera model.
So why not using -exif:all with exiftool instead of copy individual tags.