A "model" can mean "a pattern to follow." "They modeled their work on classical paintings" means "they used classical paintings as a model." Even when they were not exactly _copying_ them, they followed the same style. For example, the photographer Eadward Muybridge was a pioneer in action studies--not quite cinematography, because he devised systems that shot images in quick succession but never put them together to create a moving picture. Anyway, in many of his studies women are picking up Grecian urns, even though of course British women didn't use urns like that in the 1880s. But in that era art = ancient Grecian art. Do a web search on "eadward muybridge woman lifting an urn" for an example