1. A method comprising: obtaining video data depicting a head of a user; obtaining depth data associated with the video data; selecting seed pixels for a hair-identification flood fill for identifying pixels depicting hair of the head of the user, the seed pixels selected at least in part by using the obtained depth data; performing the hair-identification flood fill from the selected seed pixels, the hair-identification flood fill assigning respective distance-cost values to pixels of the video data based on respective position-space-cost values and respective color-space-cost values; and identifying a persona of the user from the video data based at least in part on the respective distance-cost values assigned by the hair-identification flood fill.