The resulting cast shadow can be a remarkable design element, like Frank Brangwyn in one of his famous bridge paintings. 
Sometimes the forms apart from the composition of shadows on the subject. The movement of the sun shade morning moved pretty quickly on Flatiron building. 
Samuel Prout effectively used the shadow in this watercolor Palazzo Contarini in Venice. The edge of the shape of the shadow follows the building of fat terrain. It also sets up opportunities for the tonal design. Some figures are seen in the light against shadow forms, while other figures are in relative obscurity against a bright background.
