AVHRR rectification using orbital navigation and image matching

摘要

Polar orbital satellites with low spatial resolution sensors, such as the AVHRR, provide global coverage with a short repetition period. The data is directly transmitted to ground stations, and can be distributed immediately after data acquisition. Near real time applications can be implemented if the adequate processing tools are available. One task usually needed is the geometric correction of image data. Automatic methods, based on satellite orbital parameters, can in some cases provide satisfactory results. However, the identification of Ground Control Points (GCPs) is generally required in order to achieve registration errors below the pixel size. A fully automatic method for the geometric registration of AVHRR data is proposed here. The method comprises four stages: (i) an initial image transformation based on orbital parameters, (ii) image segmentation of this image into 3 main classes (land, water, cloud) and 9 additional classes of mixed water and land at various levels, (iii) automatic GCP collection by image matching, (iv) final image production combining both orbital and GCP information. The method was tested on ten images of the Iberian Peninsula, and proved effective in accurately geo-referencing sub-sections of an AVHRR scene of medium dimension in a few minutes.