<title>Synthesis of photorealistic whole earth imagery</title>

Abstract

A variety of remotely sensed digital imagery data sources now exists that enable the computer graphics synthesis of convincing real, whole Earth images similar to those recorded by orbiting astronauts using conventional photographic techniques. Within data resolution limitations, such data sets can be rendered (using three dimensional graphics technologies) to produce views of our planet from any vantage point. By utilizing time series of collected data in conjunction with synthetic Lambertian lighting models, such views can be animated, in time, to produce dynamic visualizations of the Earth and its weather systems. This paper describes an effort to produce an animation for commercial use in the broadcast industry. To be used for entertainment purposes, the animation was designed to show the dramatic, fluid nature of the Earth as it might appear from space. GOES infra red imagery was collected over the western hemisphere for 15 days at half hour intervals. This imagery was processed to remove sensor artifacts and drop-outs and to create synthetic imagery which appears to the observer to be nature visible wavelength imagery. Cloud free imagery of the entire planet, re- sampled to 4 Km resolution, based on mosaicked AVHRR, polar orbiting imagery was used as a 'base map' to reflect surface features. Graphics techniques to simulate Lambertian lighting of the Earth surface were used to impart the effects of changing solar illumination. All of the graphics elements were then, on a frame by frame basis, digitally composited together, with varying cloud transparency to produce the final rendered imagery, which in turn is recorded onto video tape.