Along-scan radiometric gradient in Landsat images: understanding the relation between floristic and remote sensing information in tropical forests
Muro, Javier (2014-11-13)
Along-scan radiometric gradient in Landsat images: understanding the relation between floristic and remote sensing information in tropical forests
Muro, Javier
(13.11.2014)
Turun yliopisto
avoin
Julkaisun pysyvä osoite on:
https://urn.fi/URN:NBN:fi-fe2014111346276
https://urn.fi/URN:NBN:fi-fe2014111346276
Kuvaus
Siirretty Doriasta
Tiivistelmä
The along-scan radiometric gradient causes severe interpretation problems in Landsat
images of tropical forests. It creates a decreasing trend in pixel values with the column
number of the image. In practical applications it has been corrected assuming the trend
to be linear within structurally similar forests. This has improved the relation between
floristic and remote sensing information, but just in some cases. I use 3 Landsat images
and 105 floristic inventories to test the assumption of linearity, and to examine how the
gradient and linear corrections affect the relation between floristic and Landsat data.
Results suggest the gradient to be linear in infrared bands. Also, the relation between
floristic and Landsat data could be conditioned by the distribution of the sampling sites
and the direction in which images are mosaicked. Additionally, there seems to be a
conjunction between the radiometric gradient and a natural east-west vegetation
gradient common in Western Amazonia. This conjunction might have enhanced
artificially correlations between field and remotely-sensed information in previous
studies. Linear corrections may remove such artificial enhancement, but along with true
and relevant spectral information about floristic patterns, because they can´t separate
the radiometric gradient from a natural one.
images of tropical forests. It creates a decreasing trend in pixel values with the column
number of the image. In practical applications it has been corrected assuming the trend
to be linear within structurally similar forests. This has improved the relation between
floristic and remote sensing information, but just in some cases. I use 3 Landsat images
and 105 floristic inventories to test the assumption of linearity, and to examine how the
gradient and linear corrections affect the relation between floristic and Landsat data.
Results suggest the gradient to be linear in infrared bands. Also, the relation between
floristic and Landsat data could be conditioned by the distribution of the sampling sites
and the direction in which images are mosaicked. Additionally, there seems to be a
conjunction between the radiometric gradient and a natural east-west vegetation
gradient common in Western Amazonia. This conjunction might have enhanced
artificially correlations between field and remotely-sensed information in previous
studies. Linear corrections may remove such artificial enhancement, but along with true
and relevant spectral information about floristic patterns, because they can´t separate
the radiometric gradient from a natural one.