Satellite daytime image classification for global studies of Earth's surface parameters from polar orbiters
作者:
G.GARTK GUTMAN,
期刊:
International Journal of Remote Sensing
(Taylor Available online 1992)
卷期:
Volume 13,
issue 2
页码: 209-234
ISSN:0143-1161
年代: 1992
DOI:10.1080/01431169208904036
出版商: Taylor & Francis Group
数据来源: Taylor
摘要:
A daytime image classifier, which relics on the difference in spectral signatures of the five channels of AVHRR, is proposed. The methodology is based on the preliminary classification of each pixel with the assumption that it is clear and on subsequent tests for cloud detection. The advantage of the preliminary classification is in that the threshold values for spatial variability tests are dependent upon the surface types identified thus allowing more data to be retained over some complex terrains. A fine dynamic cloud filter was designed with the assumption that the absolute value of the near-IR to visible reflectance ratio correlates negatively with surface temperature. The climatic thermal thresholds can then be updated using a clear observation encountered in an array of pixels. Application of the proposed technique is demonstrated on two examples with 1 km resolution AVHRR data and one example with a subset of sampled 30 km resolution AVHRR data from ISCCP. A quantitative validation is done by comparing the cloud amount from ISCCP C1-product with that derived using the present method for the same equal-area grid cells.
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