Abstract

As the primary archive for the data acquired by the Landsat series of spacecraft, the U.S. Geological Survey Center for Earth Resources Observation and Science (EROS) is responsible for the processing systems that capture, correct, and distribute Landsat image data products. The Landsat ground system includes product generation components that apply the radiometric and geometric processing necessary to convert the digital detector samples acquired by the sensor to top-of-atmosphere radiance measurements referenced to an Earth-fixed coordinate system. These product generation systems implement geometric correction algorithms that use the instrument and spacecraft support data, provided in the Landsat data stream, to construct a model of the geometric relationship between the acquired image data samples and an Earth-fixed ground reference system. These support data include onboard measurements of instrument timing, spacecraft attitude (orientation) and jitter, and estimates of the spacecraft position and velocity derived from ground tracking data. The accuracy of the basic systematic geometric registration model is limited by uncertainties in these supporting data. In particular, the spacecraft position and attitude data typically contain residual biases on the order of tens to hundreds of meters. Fortunately, these errors are usually slowly varying, allowing for the registration of multiple Landsat images using simple, low-order techniques. When higher-accuracy products are required, additional capabilities of the Landsat ground system are employed to perform more precise geometric correction.