Pierre Henri de Valenciennes
Pierre Henri de Valenciennes (1750-1819) was a french landscape painter. He worked in Rome from 1778-1782 where he developed techniques of 'landscape portraits'. He was one of the first to champion and theorise open air painting, with his studies of landscapes directly from nature allowing him to observe subtle changes in a same landscape depending on weather and time of day. This technique would later be developed much further by the Impressionists.