We introduce a visualization that interweaves spatial and temporal structures of photo collections into explorable pathways. Existing photo browsing interfaces typically use space and time separately for sorting, filtering, or mapping photos. What remains missing is an integrated visual form that represents the photographic journey itself. This is particularly relevant for the individual photographer's archive, where their unique lifeline is written into the collection, and it is this spatiotemporal trajectory that gives necessary context and meaning to the work. Inspired by the winding nature of rivers, fluid interaction, and un/foldable visualizations, Meandering Photo Lines visualizes adjustable pathways through a photo collection across space, time, and topics. Two complementary views enable visual exploration at different scales: A grid-based arrangement of photo clusters offers a more analytical overview, while meandering spatiotemporal curves facilitate more serendipitous and reflective exploration. Animated transformations connect these two views seamlessly for multiscale navigation from spatiotemporal cluster signatures down to chronological photo series and individual photographs. We demonstrate our approach through two case studies: an archive of approximately 100,000 photographs documenting the Jewish diaspora life worldwide from 1978 to 2021 and a personal smartphone collection of around 20,000 pictures. Qualitative feedback from a think-aloud study indicates that our approach supports both analytical examination and curiosity-driven engagement.
Project website: https://uclab.fh-potsdam.de/photolines/