PHP Extract Gps Exif Data

PHP extract GPS EXIF data

According to http://en.wikipedia.org/wiki/Geotagging, ( [0] => 46/1 [1] => 5403/100 [2] => 0/1 ) should mean 46/1 degrees, 5403/100 minutes, 0/1 seconds, i.e. 46°54.03′0″N. Normalizing the seconds gives 46°54′1.8″N.

This code below should work, as long as you don't get negative coordinates (given that you get N/S and E/W as a separate coordinate, you shouldn't ever have negative coordinates). Let me know if there is a bug (I don't have a PHP environment handy at the moment).

//Pass in GPS.GPSLatitude or GPS.GPSLongitude or something in that format
function getGps($exifCoord)
{
  $degrees = count($exifCoord) > 0 ? gps2Num($exifCoord[0]) : 0;
  $minutes = count($exifCoord) > 1 ? gps2Num($exifCoord[1]) : 0;
  $seconds = count($exifCoord) > 2 ? gps2Num($exifCoord[2]) : 0;

  //normalize
  $minutes += 60 * ($degrees - floor($degrees));
  $degrees = floor($degrees);

  $seconds += 60 * ($minutes - floor($minutes));
  $minutes = floor($minutes);

  //extra normalization, probably not necessary unless you get weird data
  if($seconds >= 60)
  {
    $minutes += floor($seconds/60.0);
    $seconds -= 60*floor($seconds/60.0);
  }

  if($minutes >= 60)
  {
    $degrees += floor($minutes/60.0);
    $minutes -= 60*floor($minutes/60.0);
  }

  return array('degrees' => $degrees, 'minutes' => $minutes, 'seconds' => $seconds);
}

function gps2Num($coordPart)
{
  $parts = explode('/', $coordPart);

  if(count($parts) <= 0)// jic
    return 0;
  if(count($parts) == 1)
    return $parts[0];

  return floatval($parts[0]) / floatval($parts[1]);
}

Issues extracting exif data for exif 2.3 using PHP Version 5.2.9

I also have a Fujifilm camera with the same problem, but I think I've found the solution, I've raised a PHP bug report here:
https://bugs.php.net/bug.php?id=66443

If you can compile PHP from source, increase the value of MAX_IFD_NESTING_LEVEL in the exif.c file. I raised it from 100 to 200 and it appears to have fixed the problem.

Mapping exif data to long/lat

You devide the minutes and seconds by 100, but well, you shouldn't:

$d = $deg + ((($min/60) + ($sec/3600))/100);

should be:

$d = $deg + (($min/60) + ($sec/3600));

one minute is 1/60 degree and a second is 1/60 minute.

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for a more thorough answer, see here: PHP extract GPS EXIF data

PHP exif_read_data no longer extracts GPS location

This is most likely due to a regression from a security fix that was causing the ext/exif extension to stop parsing in case of an "unknown" format.

This should be fixed in the 7.x branches (7.0.10 and 7.1.0 Beta 1) should contain a proper fix for these, although it was not merged to the 5.x branches, it could likely find its way there.

If you want a patch (which should be fairly easy to convert into 5.x), then I committed it here:
http://git.php.net/?p=php-src.git;a=commit;h=aabcb5481d9e717df77192dab2894468b9fc63b4

Here is a little background on how ext/exif works and what went wrong:

Internally when we parse the exif data, it will read out the standard exif tags as provided by the spec, however certain formats, have certain custom tags. These are usually parsed too, however ext/exif is limited in the sense that we only (in stable branches including 7.1) support 6 formats with extended tags (the list for each format is baked into the extension). This is where the regression comes in. When parsing the EXIF data, it is done in the following order:

• Standard EXIF data
• Look for known formats for parsing custom tags, if a matching signature is found, then parse them
• Parse additional data, like thumbnail, GPS etc

The security fix caused a regression, because you could craft fake signatures and bypass this internally, which could cause invalid reads. The fix would then bail the parsing in case of a signature mismatch in the list of baked in signatures from formats we know, thus stopping to parse and not returning data like thumbnails, causing exif_thumbnail() to essentially not be usable for any but the 6 formats.

The fix currently in the 7.x branches, restores this behavior and simply continues to parse those additional tags, so those functions and other formats we do not directly support, will once again work.

Besides that, in 7.2, I have been adding support for Samsung, Panasonic and DJI specific tags, and I'm currently looking into Sony specific data too. We have a bug report at php.net which sparkled it all in case you are interested in looking more in depth with this: https://bugs.php.net/bug.php?id=72735. And should this patch not fix your issue, you are more than welcome to submit a bug report so we can look into resolving this.

I hope this was helpful to you, and thanks for helping to make PHP even greater!

PHP Convert Exif GPS data to Google friendly values

I found that same formula, and it didn't work for me either. What I finally figured out, and what worked for me, was:

function toDecimal($deg, $min, $sec, $hem) 
{
    $d = $deg + ((($min/60) + ($sec/3600))/100);
    return ($hem=='S' || $hem=='W') ? $d*=-1 : $d;
}

Extracting EXIF data displaying 'Array'

It is, because it is an array.

print_r($val);

http://codepad.viper-7.com/PPJtsB

GPSTrack from exif

It is rational64u (as used in latitudes and longitudes, and in many places in EXIF) so a float is represented by two integers, a numerator and a denominator.

To get the float, you just divide the two:

degree = numerator / denominator 

so

degree = numerator / denominator = 116001 / 424 = 273.587264150943

Usual warning: carious computer languages will do an integer division if the two operand are integer, so you may need to cast them to floats before doing the division.

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