Determination of the Normalized Difference Vegetation Index (NDVI) with Top-of-Canopy (TOC) Reflectance from a KOMPSAT-3A Image Using Orfeo ToolBox (OTB) Extension

Abstract

Surface reflectance data obtained by the absolute atmospheric correction of satellite images are useful for land use applications. For Landsat and Sentinel-2 images, many radiometric processing methods exist, and the images are supported by most types of commercial and open-source software. However, multispectral KOMPSAT-3A images with a resolution of 2.2 m are currently lacking tools or open-source resources for obtaining top-of-canopy (TOC) reflectance data. In this study, an atmospheric correction module for KOMPSAT-3A images was newly implemented into the optical calibration algorithm in the Orfeo Toolbox (OTB), with a sensor model and spectral response data for KOMPSAT-3A. Using this module, named OTB extension for KOMPSAT-3A, experiments on the normalized difference vegetation index (NDVI) were conducted based on TOC reflectance data with or without aerosol properties from AERONET. The NDVI results for these atmospherically corrected data were compared with those from the dark object subtraction (DOS) scheme, a relative atmospheric correction method. The NDVI results obtained using TOC reflectance with or without the AERONET data were considerably different from the results obtained from the DOS scheme and the Landsat-8 surface reflectance of the Google Earth Engine (GEE). It was found that the utilization of the aerosol parameter of the AERONET data affects the NDVI results for KOMPSAT-3A images. The TOC reflectance of high-resolution satellite imagery ensures further precise analysis and the detailed interpretation of urban forestry or complex vegetation features.

Application of the Random Forest Classifier to Map Irrigated Areas Using Google Earth Engine

“…Healthy vegetation reflects more infrared and absorbs more red and blue portions of the electromagnetic spectrum. The red and near-infrared bands are important for calculating NDVI and other vegetation indices as the blue portion is affected by atmospheric scattering [43]. In areas with a single modal annual rainfall pattern, there is less absorption of the visible light and low reflection of the infrared light during the dry season (Figure 5), resulting in low NDVI values.…”

UAV Photogrammetry for Concrete Bridge Inspection Using Object-Based Image Analysis (OBIA)

“…The use of an open source software is one of the main advantage of the presented method. OTB open source software proved to be a powerful tool for OBIA using photogrammetry derived images, even if developed for other applications [39,64,65].…”

An Implementation of Open Source-Based Software as a Service (SaaS) to Produce TOA and TOC Reflectance of High-Resolution KOMPSAT-3/3A Satellite Image

“…Among the open sources that provide atmospheric correction schemes or algorithms, the OTB provides an absolute atmosphere correction method that uses atmospheric variables. The absolute atmospheric correction method showed that the error with the field measurement of RadCalNet portal value was small, according to a comparative experiment using relative atmospheric correction and absolute atmospheric correction [46,47]. The KOMPSAT-3/3A for OTB extension was implemented [48], and the TOA and TOC reflectance products using this extension were validated with RVUS, BTCN, BSCN, and LCFR data in RadCalNet [49,50].…”