Challenges in a cloudy NZ for analysis ready satellite imagery скачать в хорошем качестве

Challenges in a cloudy NZ for analysis ready satellite imagery

Repeat frequencies of optical remote sensing satellites have increased markedly over the last 40 years, but there is still dependence on clear skies to acquire usable imagery. To increase the quality of data, composited mosaics of satellite imagery can be used. We have developed an automated method for clearing clouds and producing different types of composited mosaics suitable for use in cloud-affected countries, such as New Zealand. Cloud detection uses a parallax method to produce an initial cloud layer, followed by an object-based cloud and shadow approach to remove false cloud detections. There are several scoring approaches for choosing best-pixel composites with minimal remaining cloud. The automated mosaicking approach has produced Sentinel-2 mosaics of New Zealand for eight successive summers, 2015/16 through 2022/23, with remaining cloud being less than 0.1%. Contributing satellite overpasses are typically of the order of 100. Improvements to cloud clearing have enabled the use of all possible Sentinel-2 imagery to produce automatic mosaics capable of regular land monitoring, at reasonable cost.