dc.contributor.author |
Ramoelo, Abel
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dc.contributor.author |
Skidmore, AK
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dc.contributor.author |
Schlerf, M
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dc.contributor.author |
Mathieu, Renaud SA
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dc.contributor.author |
Heitkönig, IMA
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dc.date.accessioned |
2011-06-27T12:38:36Z |
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dc.date.available |
2011-06-27T12:38:36Z |
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dc.date.issued |
2011 |
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dc.identifier.citation |
Ramoelo, A., Skidmore, A.K., Schlerf, M., et al. 2011. Water-removed spectra increase the retrieval accuracy when estimating savanna grass nitrogen and phosphorus concentrations. ISPRS Journal of Photogrammetry and Remote Sensing, Vol. 66(4), pp 408-417 |
en_US |
dc.identifier.issn |
0924-2716 |
|
dc.identifier.uri |
http://www.sciencedirect.com/science?_ob=MImg&_imagekey=B6VF4-52959TK-1-1&_cdi=6000&_user=958262&_pii=S0924271611000232&_origin=&_coverDate=07%2F31%2F2011&_sk=999339995&view=c&wchp=dGLzVlz-zSkWA&_valck=1&md5=9bda71748ef77950871b0cceefb11518&ie=/sdarticle.pdf
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dc.identifier.uri |
http://hdl.handle.net/10204/5070
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|
dc.description |
Copyright. 2011. This is a pre print version of the work. The definitive version is published in ISPRS Journal of Photogrammetry and Remote Sensing, Vol. 66(4) |
en_US |
dc.description.abstract |
Information about the distribution of grass foliar nitrogen (N) and phosphorus (P) is important for understanding rangeland vitality and for facilitating the effective management of wildlife and livestock. Water absorption effects in the near-infrared (NIR) and shortwave-infrared (SWIR) regions pose a challenge for nutrient estimation using remote sensing. The aim of this study was to test the utility of water-removed (WR) spectra in combination with partial least-squares regression (PLSR) and stepwise multiple linear regression (SMLR) to estimate foliar N and P, compared to spectral transformation techniques such as first derivative, continuum removal and log-transformed (Log(1/R)) spectra. The study was based on a greenhouse experiment with a savanna grass species (Digitariaeriantha). Spectral measurements were made using a spectrometer. The D. eriantha was cut, dried and chemically analyzed for foliar N and P concentrations. WR spectra were determined by calculating the residual from the modelled leaf water spectra using a nonlinear spectral matching technique and observed leaf spectra. Results indicated that the WR spectra yielded a higher N retrieval accuracy than a traditional first derivative transformation (R2 = 0.84, RMSE = 0.28) compared to R2 = 0.59, RMSE = 0.45 for PLSR. Similar trends were observed for SMLR. The highest P retrieval accuracy was derived from WR spectra using SMLR (R2 = 0.64, RMSE = 0.067), while the traditional first derivative and continuum removal resulted in lower accuracy. Only when using PLSR did the first derivative result in a higher P retrieval accuracy (R2 = 0.47, RMSE = 0.07) than the WR spectra (R2 = 0.43, RMSE = 0.070). It was concluded that the water removal technique is a promising technique to minimize the perturbing effect of foliar water content when estimating grass nutrient concentrations. |
en_US |
dc.language.iso |
en |
en_US |
dc.publisher |
Elsevier Publishers |
en_US |
dc.relation.ispartofseries |
Workflow;6696 |
|
dc.subject |
Nitrogen concentration |
en_US |
dc.subject |
Phosphorus concentration |
en_US |
dc.subject |
Water removal |
en_US |
dc.subject |
Continuum removal |
en_US |
dc.subject |
Bootstrapping |
en_US |
dc.title |
Water-removed spectra increase the retrieval accuracy when estimating savanna grass nitrogen and phosphorus concentrations |
en_US |
dc.type |
Article |
en_US |
dc.identifier.apacitation |
Ramoelo, A., Skidmore, A., Schlerf, M., Mathieu, R. S., & Heitkönig, I. (2011). Water-removed spectra increase the retrieval accuracy when estimating savanna grass nitrogen and phosphorus concentrations. http://hdl.handle.net/10204/5070 |
en_ZA |
dc.identifier.chicagocitation |
Ramoelo, Abel, AK Skidmore, M Schlerf, Renaud SA Mathieu, and IMA Heitkönig "Water-removed spectra increase the retrieval accuracy when estimating savanna grass nitrogen and phosphorus concentrations." (2011) http://hdl.handle.net/10204/5070 |
en_ZA |
dc.identifier.vancouvercitation |
Ramoelo A, Skidmore A, Schlerf M, Mathieu RS, Heitkönig I. Water-removed spectra increase the retrieval accuracy when estimating savanna grass nitrogen and phosphorus concentrations. 2011; http://hdl.handle.net/10204/5070. |
en_ZA |
dc.identifier.ris |
TY - Article
AU - Ramoelo, Abel
AU - Skidmore, AK
AU - Schlerf, M
AU - Mathieu, Renaud SA
AU - Heitkönig, IMA
AB - Information about the distribution of grass foliar nitrogen (N) and phosphorus (P) is important for understanding rangeland vitality and for facilitating the effective management of wildlife and livestock. Water absorption effects in the near-infrared (NIR) and shortwave-infrared (SWIR) regions pose a challenge for nutrient estimation using remote sensing. The aim of this study was to test the utility of water-removed (WR) spectra in combination with partial least-squares regression (PLSR) and stepwise multiple linear regression (SMLR) to estimate foliar N and P, compared to spectral transformation techniques such as first derivative, continuum removal and log-transformed (Log(1/R)) spectra. The study was based on a greenhouse experiment with a savanna grass species (Digitariaeriantha). Spectral measurements were made using a spectrometer. The D. eriantha was cut, dried and chemically analyzed for foliar N and P concentrations. WR spectra were determined by calculating the residual from the modelled leaf water spectra using a nonlinear spectral matching technique and observed leaf spectra. Results indicated that the WR spectra yielded a higher N retrieval accuracy than a traditional first derivative transformation (R2 = 0.84, RMSE = 0.28) compared to R2 = 0.59, RMSE = 0.45 for PLSR. Similar trends were observed for SMLR. The highest P retrieval accuracy was derived from WR spectra using SMLR (R2 = 0.64, RMSE = 0.067), while the traditional first derivative and continuum removal resulted in lower accuracy. Only when using PLSR did the first derivative result in a higher P retrieval accuracy (R2 = 0.47, RMSE = 0.07) than the WR spectra (R2 = 0.43, RMSE = 0.070). It was concluded that the water removal technique is a promising technique to minimize the perturbing effect of foliar water content when estimating grass nutrient concentrations.
DA - 2011
DB - ResearchSpace
DP - CSIR
KW - Nitrogen concentration
KW - Phosphorus concentration
KW - Water removal
KW - Continuum removal
KW - Bootstrapping
LK - https://researchspace.csir.co.za
PY - 2011
SM - 0924-2716
T1 - Water-removed spectra increase the retrieval accuracy when estimating savanna grass nitrogen and phosphorus concentrations
TI - Water-removed spectra increase the retrieval accuracy when estimating savanna grass nitrogen and phosphorus concentrations
UR - http://hdl.handle.net/10204/5070
ER -
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en_ZA |