نتایج جستجو برای: vegetation indices

تعداد نتایج: 127108  

2005
G. Menz

The actual condition of vegetation cover is represented by its spectral signature. Photosynthetic active vegetation is characterized by a low reflectance in the red and a high reflectance in the near infrared spectra. This specific feature is used to calculate different vegetation indices. One index is the MERIS Global Vegetation Index (MGVI), the other one is the Red Edge Position (REP), which...

2002
Driss Haboudane John R. Miller Nicolas Tremblay Pablo J. Zarco-Tejada Louise Dextraze

Recent studies have demonstrated the usefulness of optical indices from hyperspectral remote sensing in the assessment of vegetation biophysical variables both in forestry and agriculture. Those indices are, however, the combined response to variations of several vegetation and environmental properties, such as Leaf Area Index (LAI), leaf chlorophyll content, canopy shadows, and background soil...

Journal: :Remote Sensing 2016
Zhihui Wang Tiejun Wang Roshanak Darvishzadeh Andrew K. Skidmore Simon D. Jones Lola Suárez William Woodgate Uta Heiden Marco Heurich John W. Hearne

Hyperspectral remote sensing serves as an effective tool for estimating foliar nitrogen using a variety of techniques. Vegetation indices (VIs) are a simple means of retrieving foliar nitrogen. Despite their popularity, few studies have been conducted to examine the utility of VIs for mapping canopy foliar nitrogen in a mixed forest context. In this study, we assessed the performance of 32 vege...

Journal: :Traitement du Signal 2015
Tran-Thanh Ngo Christophe Collet Vincent Mazet

We propose a new method to simultaneously detect shadows and vegetation in remote sensing images. Several shadow and vegetation indices are merged with the Dempster-Shafer (DS) theory so as to increase the reliability and accuracy of the segmentation. The per-pixel DS fusion is incorporated in a Markovian context to obtain an optimal and regularized segmentation result. Evaluation on aerial ima...

Journal: :desert 2008
a. a. shamsipour s. k. alavipanah h. mohammadi a. azizi f. khoshakhlagh

drought is a major problematic phenomenon for the mostly semi-arid country of iran. the north centralregions of iran (north of esfahan and ghom province) have suffered from severe droughts several times duringthe last three decades. the frequent occurrence of drought in these regions is due to low and inconsistentprecipitation, abnormally high temperatures, increases in surface albedo and evapo...

2017
Hania AL-Saddik Jean-Claude Simon Frédéric Cointault

Spectral measurements are employed in many precision agriculture applications, due to their ability to monitor the vegetation's health state. Spectral vegetation indices are one of the main techniques currently used in remote sensing activities, since they are related to biophysical and biochemical crop variables. Moreover, they have been evaluated in some studies as potentially beneficial for ...

Journal: :Journal of economic entomology 2006
Mustafa Mirik Gerald J Michels Sabina Kassymzhanova-Mirik Norman C Elliott Roxanne Bowling

Although spectral remote sensing techniques have been used to study many ecological variables and biotic and abiotic stresses to agricultural crops over decades, the potential use of these techniques for greenbug, Schizaphis graminum (Rondani) (Hemiptera: Aphididae) infestations and damage to wheat, Triticum aestivum L., under field conditions is unknown. Hence, this research was conducted to i...

2015
H. Adhikari J. Heiskanen E. E. Maeda P. K. E. Pellikka

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 me...

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