Motion capture is used when live-action actors wear special suits that allow computers to copy their movements into CG characters.
mˈoʊʃən kˈæptʃɚɹ ɪz jˈuːzd wɛn lˈaɪvˈækʃən ˈæktɚz wˈɛɹ spˈɛʃəl sˈuːts ðæt ɐlˈaʊ kəmpjˈuːɾɚz tə kˈɑːpi ðɛɹ mˈuːvmənts ˌɪntʊ sˌiːdʒˈiː kˈæɹɪktɚz.