Eye tracking white sclera (limbus tracking). It presents another challenge for vertical eye movements due to obstruction of eyelids. Eye-tracking setups vary greatly: some are head-mounted, some require the head to be stable (for example, with a chin rest), and some function remotely and automatically track the head during motion. Most use a sampling rate of at least 30 Hz. Although 50/60 Hz is more common, today many video-based eye trackers run at 240, 350 or even 1000/1250 Hz, speeds needed in order to capture fixational eye movements or correctly measure saccade dynamics. Eye movements are typically divided into fixations and saccades
His Eye Is on the Sparrow soundtrack although admitting "Houston sounds as commanding as one can expect from a later recording." "Entertainment Weekly" editor Melissa Maerz called it "a gorgeously rippling solo" with Houston "testif[ying ...] that Jesus is watching over her." Jody Rosen of "Rolling Stone" panned the cover, saying "Houston sings – and croaks – in a voice octaves lower than in her prime. At times the song has a ravaged magnificence, but mostly it's painful." There are many arrangements of the hymn that have been produced since its original publication. These include: His Eye Is on the Sparrow "His Eye Is on the