1. A method of incorporating the radiance and transmittance of a real cloud into a simulated a real two-dimensional scene, comprising the steps of: a) extracting the radiance and transmittance from a depiction of a real cloud; b) converting the radiance and transmittance of the previous step to the radiance and transmittance of a desired material; c) applying the result of the previous step to a simulated two-dimensional scene at least once; and d) scaling each application of the previous step to a size that depicts a desired nearness of each cloud added to the simulated two-dimensional scene.