Guide frames improve centerline estimation of complex postures in WormTracer.

Precise estimation of body posture is essential for analyzing animal behavior. C. elegans exhibits a variety of complex postures, such as turning and looping, for which centerline extraction is challenging. WormTracer, an algorithm designed to ensure temporal continuity of centerlines, enabled reliable centerline extraction. However, accurate estimation remains difficult without human intervention in animals exhibiting prolonged, complex postures. Here, we present an updated version of WormTracer that accepts user-revised centerlines as guide frames, enabling accurate estimation even during prolonged complex postures. In addition, we provide a Napari plugin, Napari-WormTracer, which allows users to manually revise centerlines estimated by WormTracer.