Export GPS information from Photos.app

Apps such as GeoTag or others allow me to import GPX tracks (storing GPS information together with time information).

I can then use this geo information to automatically add a location to some photos (e.g., taken with my DSLR which does not have a GPS chip).

Since I often walk around with my iPhone and take photos both on my DSLR and my iPhone, I'd like to extract the GPS information out of Photos.app and use this information in other apps.

Is anybody aware of a way to extract this information?

PS: Please do not recommend to have a GPS tracking logger always running on the iPhone.