Artist Stephen Wiltshire neared completion of his 18-foot-long, detailed panorama of New York City on Thursday. The autistic man spent the week at Pratt Institute in Brooklyn, drawing the city from memory after a 45-minute helicopter tour. The artist will be at work through Friday. ‘The Early Show’ on CBS has tracked Wiltshire’s daily progress on the latest of his ambitious renderings of world capitals drawn after a brief look.