Does topographic normalization of landsat images improve fractional tree cover mapping in tropical mountains?

Tutkimustuotos: ArtikkelijulkaisuKonferenssiartikkeliTieteellinenvertaisarvioitu

Kuvaus

Fractional tree cover (Fcover) is an important biophysical variable for measuring forest degradation and characterizing land cover. Recently, atmospherically corrected Landsat data have become available, providing opportunities for high-resolution mapping of forest attributes at global-scale. However, topographic correction is a pre-processing step that remains to be addressed. While several methods have been introduced for topographic correction, it is uncertain whether Fcover models based on vegetation indices are sensitive to topographic effects. Our objective was to assess the effect of topographic correction on the accuracy of Fcover modelling. The study area was located in the Eastern Arc Mountains of Kenya. We used C-correction as a digital elevation model (DEM) based correction method. We examined if predictive models based on normalized difference vegetation index (NDVI), reduced simple ratio (RSR) and tasseled cap indices (Brightness, Greenness and Wetness) are improved if using topographically corrected data. Furthermore, we evaluated how the results depend on the DEM by correcting images using available global DEM (ASTER GDEM, SRTM) and a
regional DEM. Reference Fcover was obtained from wall-to-wall airborne LiDAR data. Landsat images corresponding to minimum and maximum sun elevation were analyzed. We observed that topographic correction could only improve models based on Brightness and had very small effect on the other models. Cosine of the solar incidence angle (cos i) derived from SRTM DEM showed stronger relationship with spectral bands than other DEMs. In conclusion, our results suggest that, in tropical mountains, predictive models based on common vegetation indices are not sensitive to topographic effects.
Alkuperäiskielienglanti
LehtiThe international archives of the photogrammetry, remote sensing and spatial information sciences
VuosikertaXL-7/W3
Sivut261-267
Sivumäärä7
ISSN1682-1750
DOI - pysyväislinkit
TilaJulkaistu - 11 toukokuuta 2015
OKM-julkaisutyyppiA4 Artikkeli konferenssijulkaisuussa
TapahtumaInternational Symposium on Remote Sensing of Environment - Berlin, Saksa
Kesto: 11 toukokuuta 201515 toukokuuta 2015
Konferenssinumero: 36

Lisätietoja


Volume: Volume XL-7/W3
Proceeding volume:

Tieteenalat

  • 114 Fysiikka
  • 1171 Geotieteet

Lainaa tätä

@article{614ef95aa94a4b72a60f77a1025dba84,
title = "Does topographic normalization of landsat images improve fractional tree cover mapping in tropical mountains?",
abstract = "Fractional tree cover (Fcover) is an important biophysical variable for measuring forest degradation and characterizing land cover. Recently, atmospherically corrected Landsat data have become available, providing opportunities for high-resolution mapping of forest attributes at global-scale. However, topographic correction is a pre-processing step that remains to be addressed. While several methods have been introduced for topographic correction, it is uncertain whether Fcover models based on vegetation indices are sensitive to topographic effects. Our objective was to assess the effect of topographic correction on the accuracy of Fcover modelling. The study area was located in the Eastern Arc Mountains of Kenya. We used C-correction as a digital elevation model (DEM) based correction method. We examined if predictive models based on normalized difference vegetation index (NDVI), reduced simple ratio (RSR) and tasseled cap indices (Brightness, Greenness and Wetness) are improved if using topographically corrected data. Furthermore, we evaluated how the results depend on the DEM by correcting images using available global DEM (ASTER GDEM, SRTM) and aregional DEM. Reference Fcover was obtained from wall-to-wall airborne LiDAR data. Landsat images corresponding to minimum and maximum sun elevation were analyzed. We observed that topographic correction could only improve models based on Brightness and had very small effect on the other models. Cosine of the solar incidence angle (cos i) derived from SRTM DEM showed stronger relationship with spectral bands than other DEMs. In conclusion, our results suggest that, in tropical mountains, predictive models based on common vegetation indices are not sensitive to topographic effects.",
keywords = "114 Physical sciences, 1171 Geosciences",
author = "Hari Adhikari and Janne Heiskanen and Maeda, {Eduardo Eiji} and Pellikka, {Petri Kauko Emil}",
note = "Volume: Volume XL-7/W3 Proceeding volume:",
year = "2015",
month = "5",
day = "11",
doi = "10.5194/isprsarchives-XL-7-W3-261-2015",
language = "English",
volume = "XL-7/W3",
pages = "261--267",
journal = "The international archives of the photogrammetry, remote sensing and spatial information sciences",
issn = "1682-1750",
publisher = "SPRS Council",

}

TY - JOUR

T1 - Does topographic normalization of landsat images improve fractional tree cover mapping in tropical mountains?

AU - Adhikari, Hari

AU - Heiskanen, Janne

AU - Maeda, Eduardo Eiji

AU - Pellikka, Petri Kauko Emil

N1 - Volume: Volume XL-7/W3 Proceeding volume:

PY - 2015/5/11

Y1 - 2015/5/11

N2 - Fractional tree cover (Fcover) is an important biophysical variable for measuring forest degradation and characterizing land cover. Recently, atmospherically corrected Landsat data have become available, providing opportunities for high-resolution mapping of forest attributes at global-scale. However, topographic correction is a pre-processing step that remains to be addressed. While several methods have been introduced for topographic correction, it is uncertain whether Fcover models based on vegetation indices are sensitive to topographic effects. Our objective was to assess the effect of topographic correction on the accuracy of Fcover modelling. The study area was located in the Eastern Arc Mountains of Kenya. We used C-correction as a digital elevation model (DEM) based correction method. We examined if predictive models based on normalized difference vegetation index (NDVI), reduced simple ratio (RSR) and tasseled cap indices (Brightness, Greenness and Wetness) are improved if using topographically corrected data. Furthermore, we evaluated how the results depend on the DEM by correcting images using available global DEM (ASTER GDEM, SRTM) and aregional DEM. Reference Fcover was obtained from wall-to-wall airborne LiDAR data. Landsat images corresponding to minimum and maximum sun elevation were analyzed. We observed that topographic correction could only improve models based on Brightness and had very small effect on the other models. Cosine of the solar incidence angle (cos i) derived from SRTM DEM showed stronger relationship with spectral bands than other DEMs. In conclusion, our results suggest that, in tropical mountains, predictive models based on common vegetation indices are not sensitive to topographic effects.

AB - Fractional tree cover (Fcover) is an important biophysical variable for measuring forest degradation and characterizing land cover. Recently, atmospherically corrected Landsat data have become available, providing opportunities for high-resolution mapping of forest attributes at global-scale. However, topographic correction is a pre-processing step that remains to be addressed. While several methods have been introduced for topographic correction, it is uncertain whether Fcover models based on vegetation indices are sensitive to topographic effects. Our objective was to assess the effect of topographic correction on the accuracy of Fcover modelling. The study area was located in the Eastern Arc Mountains of Kenya. We used C-correction as a digital elevation model (DEM) based correction method. We examined if predictive models based on normalized difference vegetation index (NDVI), reduced simple ratio (RSR) and tasseled cap indices (Brightness, Greenness and Wetness) are improved if using topographically corrected data. Furthermore, we evaluated how the results depend on the DEM by correcting images using available global DEM (ASTER GDEM, SRTM) and aregional DEM. Reference Fcover was obtained from wall-to-wall airborne LiDAR data. Landsat images corresponding to minimum and maximum sun elevation were analyzed. We observed that topographic correction could only improve models based on Brightness and had very small effect on the other models. Cosine of the solar incidence angle (cos i) derived from SRTM DEM showed stronger relationship with spectral bands than other DEMs. In conclusion, our results suggest that, in tropical mountains, predictive models based on common vegetation indices are not sensitive to topographic effects.

KW - 114 Physical sciences

KW - 1171 Geosciences

U2 - 10.5194/isprsarchives-XL-7-W3-261-2015

DO - 10.5194/isprsarchives-XL-7-W3-261-2015

M3 - Conference article

VL - XL-7/W3

SP - 261

EP - 267

JO - The international archives of the photogrammetry, remote sensing and spatial information sciences

JF - The international archives of the photogrammetry, remote sensing and spatial information sciences

SN - 1682-1750

ER -