# Exif Metadata
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.