From age nine, Koch had worked as assistant to the cartographer-farmer Hueber. Carstens was both his great friend and ally in the expatriate artist circle in Rome, and an important influence on his work. He shared a Rome apartment and studio with the sculptor Thorvaldsen, and developed a heroic style of landscape painting with his friend Reinhart. He also knew Schinkel in Rome, and was visited by Mendelssohn (who was scornful of the minor German painters there) in his studio. Horny and Richter were his students. The Olivier brothers met him in Vienna and were much influenced by him.