Exif Metadata

• Supported functions
• Allowing location tags
  • Android
  • iOS
• Use it with photo widget

Mergin Maps Input comes with predefined default value expression functions which can be used to read an image EXIF metadata.

Supported functions

Following functions are supported:

• read_exif('<ABSOLUTE_PATH_TO_IMAGE>', '<EXIF_TAG_STRING>')
  • returning string
• read_exif_img_direction('<ABSOLUTE_PATH_TO_IMAGE>')
  • returning number
• read_exif_latitude('<ABSOLUTE_PATH_TO_IMAGE>')
  • returning decimal number
• read_exif_longitude('<ABSOLUTE_PATH_TO_IMAGE>')
  • returning decimal number

Allowing location tags

Note that location tags have to be allowed in a camera settings. You can find the option as following:

Android

Open Camera app -> Camera settings -> Location tags.

iOS

Open Settings -> Privacy -> Location Services -> Camera (app).

Use it with photo widget

The parameter <ABSOLUTE_PATH_TO_IMAGE> can be set with an expression using value of another field. Therefore you can use a value from a text field of an attachment type as a parameter for Mergin Maps Input's EXIF functions as following:

read_exif(@project_home + '/' + "photo", 'GPSImgDirection')

You can use both Take a photo or From gallery actions of the attachment widget. While capturing a photo with a camera, GPS EXIF data are added to the photo metadata. Make sure that location permissions are allowed in Mergin Maps Input and also for your camera app.

For further examples you can check fields definitions of project lutraconsulting/test_exif (opens new window) accessible on Mergin.