Ionic picture to s3

I'm trying to avoid handling the image uploading for an Ionic app that I'm creating. The idea that I had was to directly take a picture and let the client upload it to my Amazon S3.

However, I'm confused as to how I can go about this. With the code that I currently have:

var options = {saveToPhotoAlbum: false, targetWidth: 450, targetHeight: 300};
$scope.getPhoto = function() {
    Camera.getPicture().then(function(imageURI) {
        $rootScope.image_url = imageURI; // this contains a URL
        console.log(imageURI);
    }, function(err) {
        console.err(err);
    });
};

The URL that i get back here is something like:

file:///storage/emulated/0/Android/data/com.ionicframework.app3000857/cache/1419546238582.jpg

How would I go about uploading this to S3?