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EXIF GPS data incorrect for southern hemisphere

After capturing some test images with GPS (in Australia), I noticed the co-ordinate data is incorrectly stored as Latitude N, Longitude W (instead of Latitude S, Longitude E).

Mac OS X (10.5.4)

Posted on Jul 12, 2008 12:14 AM

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61 replies

Jul 12, 2008 5:24 AM in response to npiper

Interesting -- I was trying to figure out why Flickr can't use the iPhone camera's embedded GPS info from my 1st gen iPhone. iPhoto shows my location (USA, so N and W), but Flickr, after importing the info, says that it was taken N and E (but same numerical values).

My guess was that it has something to do with this: Many apps (like Google Maps) use + and - signs to indicate hemisphere: Eastern hemisphere is + longitude, Western is - longitude. So here, I'm at -71 longitude, according to Google Maps. If Apple doesn't send a "sign", maybe it's interpreted by other systems as positive -- meaning that all these locations will be N and E.

But now I don't know -- you're in the E, so I would have expected that your longitude would be right, but not your latitude. From what you said, sounds like they're both off.

Jul 14, 2008 3:02 AM in response to jerakeen

I used exiftool to look at the file of a photo I just took on my iPhone and imported using image capture and iPhoto and the geotag data was the same for both. Wrong.

*Image Capture:*
warbook:~ bjd$ exiftool /Users/bjd/Pictures/IMG_0019.JPG | grep GPS
GPS Latitude Ref : North
GPS Longitude Ref : West
GPS Latitude : 33 deg 45' 25.20" N
GPS Longitude : 151 deg 7' 15.00" W
GPS Position : 33 deg 45' 25.20" N, 151 deg 7' 15.00" W

iPhoto:
warbook:~ bjd$ exiftool /Users/bjd/Pictures/iPhoto\ Library/Modified/2008/City\ Excursion/IMG_0019.JPG | grep GPS
GPS Latitude : 33 deg 45' 25.20"
GPS Longitude : 151 deg 7' 15.00"
GPS Position : 33 deg 45' 25.20", 151 deg 7' 15.00"

ASAIK N is positive and W is positive so as long as iPhoto is relying on signed LAT/LONG rather than specifically have the N/W then it is exactly the same and nothing has changed. Whether iPhoto imported it or Image Capture imported it.

Jul 15, 2008 1:17 AM in response to Brendan Daly

There is nothing wrong with the iPhone geotagging. (see Jerakeen's post earlier in this thread) The wrong-hemisphere problem only occurs when you import the photo through iPhoto on your mac, AND THEN edit the photo somehow (crop it, for example, etc.). iPhoto then strips part of the EXIF data so that the East and West, North and South identifiers are removed (leaving it unclear if the photo was taken at 118 deg West, or 118 deg East, for example).

To avoid this, import to your mac using image capture instead of iPhoto. You can then import the photo into iPhoto if you like, but as soon as you edit the photo, the lat/lon references (not the values, just the indicators that tell whether the number is E or W of the prime meridian, or N or S of the equator) are stripped. This bug has been with iPhoto for a long time. (see this thread on flickr from over a year ago: http://www.flickr.com/groups/geotagging/discuss/72157600040087961/) Maybe now that it's getting renewed attention from iphone users, apple will finally fix it. Geotagging photos has been a niche interest up to now, but since the iphone does it automatically, there might be enough squeaky wheels to get Apple to finally fix iphoto.

Jul 15, 2008 1:35 AM in response to dgalvan123

You should have read my reply to the use of image capture. The problem occurred when I used Image Capture. I am in the southern hemisphere ie S - so that N is wrong. iPhoto may have other issues with geotagging that is manifest when the image is editted, I am not doubting it.

BUT using image capture +*does not*+ fix this problem, so, the exif data is wrong as it is encoded in the image or both iPhoto and image capture are breaking the tag data as it comes across. It is not merely an iPhoto issue.

Using image capture did NOT fix the problem.

EXIF GPS data incorrect for southern hemisphere

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