Finnish painter, born at Viipuri (now Vyborg in Russia). He trained at various art schools in Finland and elsewhere, notably the Académie Julian, Paris. His early work included landscapes, portraits, and still-lifes, but after the Second World War he became one of the pioneers of abstract art in Finland. Initially he moved to abstraction through simplifying natural forms, but in the 1960s his style became more geometrical and his work sometimes verged on Op art. Vanni's output included several large murals in public buildings. He was influential not only through such works, but also through his teaching at art schools in Helsinki.