 Monsters University is the first Pixar film that used global illumination , a new lighting system introduced as part of the overhaul of the rendering system used since the first Toy Story film . In the planning stage of the film , director of photography , Jean @-@ Claude <unk> , asked " What if we made these lights just work ? " Before the new system , artists had to build reflections and shadows manually , which became increasingly complex as the models and the setups became more technologically advanced . The new lighting system uses path tracing , a technique that imitates the behaviour of the light in the real world ; this <unk> the process , delivered more realism , produced soft shadows , and let the artist spend more time on models and complex scenes – some of which contained thousands of light sources . 
