Geo-tag custom field

Thank you for sending me four of your images for my investigation. I am using the metadata embedded in your “CIMG2510_reduced” image as an example.

You are interested in four data elements:

• Camera model
• Latitude
• Longtitude
• Altitude

There are two EXIF fields related to “Camera model”:

• ‘Make’ => ‘CASIO COMPUTER CO.,LTD.’
• ‘Model’ => ‘EX-ZR100 ‘,

The ‘Model’ value is also available in the WordPress image_meta array as ‘camera’. You can enter “Make” or “Model” as the “EXIF Value” on the Settings/Media Library Assistant IPTC/EXIF tab to map these to a custom field. In my next version (v1.50) you will be able to combine the two values into a single custom field using the new Content Template feature I am adding in that release.

The GPS information is more complicated. In Adobe Photoshop, the “File/File Info…” dialog box, Raw Data tab reports this information as:

<exif:GPSVersionID>2.2.0.0</exif:GPSVersionID>
<exif:GPSLatitude>44,7.5669N</exif:GPSLatitude>
<exif:GPSLongitude>145,5.1534E</exif:GPSLongitude>
<exif:GPSAltitudeRef>0</exif:GPSAltitudeRef>
<exif:GPSAltitude>230528/933</exif:GPSAltitude>
<exif:GPSTimeStamp>2013-08-09T01:00:34-07:00</exif:GPSTimeStamp>
<exif:GPSMapDatum>WGS-84</exif:GPSMapDatum>

The PHP function that MLA uses to extract EXIF data (exif_read_data) returns this information as:

'GPSVersion' => a four-byte binary value,
  'GPSLatitudeRef' => 'N',
  'GPSLatitude' =>
  array (
    0 => '44/1',
    1 => '7/1',
    2 => '50923/1497',
  ),
  'GPSLongitudeRef' => 'E',
  'GPSLongitude' =>
  array (
    0 => '145/1',
    1 => '5/1',
    2 => '38746/4209',
  ),
  'GPSAltitudeRef' => a one-byte binary value,
  'GPSAltitude' => '230528/933',
  'GPSTimeStamp' =>
  array (
    0 => '1/1',
    1 => '0/1',
    2 => '34/1',
  ),
  'GPSMapDatum' => 'WGS-84',
  'GPSDateStamp' => '2013:08:09',

The MLA EXIF mapping logic will convert the array values to comma-delimited strings. For example, ‘GPSLatitude’ will be mapped to “44/1,7/1,50923/1497”. The next MLA version (1.50) will let you store array values in a custom field without converting them to a string representation.

The Exif Standard version 2.3 (http://www.cipa.jp/english/hyoujunka/kikaku/pdf/DC-008-2010_E.pdf) document explains the structure of the above data and defines the rules for 32 GPS elements. For example:

GPSLatitude
Indicates the latitude. The latitude is expressed as three RATIONAL values giving the degrees, minutes, and seconds, respectively. If latitude is expressed as degrees, minutes and seconds, a typical format would be dd/1,mm/1,ss/1. When degrees and minutes are used and, for example, fractions of minutes are given up to two decimal places, the format would be dd/1,mmmm/100,0/1.

Using the above definition I am not sure how to get from 5669 seconds in Photoshop to the ‘50923/1497’ value returned by exif_read_data.

As an experiment I also used the getID3() library to decode the metadata. It returns the same values as exif_read_data, but it also has a “computed” array of GPS information that contains:

altitude double 247.08252947481
latitude double 44.126115750019
longitude double 145.08589042
timestamp integer 943923634
version string (8) v2.2.0.0

I don’t know if this decoding would be of more interest to you.

In summary, the GPS information is available and MLA can map it to custom fields for you. However, the format of the data might not be what you want. You could add some PHP code to your theme to convert the data to a more convenient format. There is no logic in the current or next MLA to process this data.

I hope this helps you get the data you need from your images.

The current MLA version can access anything in the “image_meta” field that WordPress creates (and Fullscreen Galleria adds to). You can find more information in the Settings/Media Library Assistant Documentation tab, “Field-level Markup Substitution Parameters” section:

meta
WordPress attachment metadata, if any, embedded in the image/audio/video file. For this category, you can code any of the field names embedded in the _wp_attachment_metadata array. The “Attachment Metadata” display in the Media/Edit Media screen will show you the names and values of these fields. Note that the fields available differ among image, audio and video attachments.

You can access the values in an [mla_gallery] shortcode by coding [+meta:image_meta.longitude+] or [+meta:image_meta.latitude+]. You can also map the values to custom fields by following the instructions in the “Custom Field Processing Options” section.

The current MLA version does not have a feature to extract the GPS information from the image and map it into the “image_meta” field. I’ve thought about adding that feature but have not started working on it.

So, the current MLA version will let you access the data already added to “image_meta”, but will not help process the images you uploaded before installing Fullscreen Galleria. I will look at adding that to the next version or so and update this topic when I have progress to report.

I have released version 1.51, which adds the ability to add or change values within the image_meta field and any other elements of the _wp_attachment_metadata array as well. The example I give in the Settings/Media Library Assistant Documentation tab adds GPS information to the image_meta, so you should find it easy to apply to your site.

I also added four more Enhanced GPS values, so the format required by the Fullscreen Galleria plugin is readily available.

Thanks for your patience and for motivating this new feature. Please let me know if you have any problems or further questions.