Complex sentence: This project in turn was divided into many separate, but identically classified, projects, one of which was Project Polaris, which was a radar, photographic (trimetrogon, or three-angle, cameras) and visual study of the entire Canadian Archipelago.
Split into simpler sentences: This project in turn was divided into a multitude of identically classified projects one of which was Project Polaris. This special project was tasked to make a radar, photographic (trimetrogon, or three-angle, cameras) and visual study of the entire Canadian Archipelago.