Ground-based imaging spectroscopy data for estimation of Antarctic moss relative vigour from remotely sensed chlorophyll content and leaf density at ASPA 135

The ground-based imaging spectroscopy data were acquired with the Headwall Photonics Micro-Hyperspec VNIR scanner (Headwall Inc., USA) attached to a computer-controlled rotating/tilting platform. The sensor unit was placed approximately 2.5 m above the ground on a single pole mounted to a geodetic tripod. The Micro-Hyperspec is a push-broom scanner, which collects light passing through a lens objective with an aperture of f/2.8 (FOV of 49.8 degrees) and through a slit entrance of 25 microns. The spectral wavelengths are split by an aberration-corrected convex holographic diffraction grating and projected onto a charge-coupled device (CCD) matrix with a digital dynamic range of 12-bits and size of 1004 by 1004 pixel units. The CCD registers the captured light split into 324 (full spectral extent, FWHM of 4.12-4.67 nm) or 162 spectral bands (binning of two neighbouring spectral pixels as a single recording unit, FWHM of 4.75-5.25 nm). To ensure a high signal-to-noise ratio and to prevent oversaturation of the CCD dynamic range, the spectral binning (162 bands) combined with an integration time of 40 milliseconds (ms) was applied and oblique hyperspectral images (azimuth viewing angles of 44 degrees and 60 degrees) were collected at two test sites

地面成像光谱数据由Headwall Photonics Micro-Hyperspec VNIR扫描仪（美国Headwall Inc.公司制造）采集，该扫描仪连接至计算机控制的旋转/倾斜平台。传感器单元被置于距地面约2.5米的高度，固定于测地三脚架上单根支柱上。Micro-Hyperspec扫描仪属于推扫式扫描仪，它通过f/2.8孔径（视场角为49.8度）的镜头目镜以及25微米宽的狭缝入口收集光线。光谱波长经校正像差的凸面全息衍射光栅分裂，并投射至具有12位数字动态范围和1004×1004像素单元大小的电荷耦合器件（CCD）矩阵。CCD记录下分裂的光，分为324（全光谱范围，半高全宽为4.12-4.67纳米）或162（将两个相邻光谱像素合并为一个记录单位，半高全宽为4.75-5.25纳米）光谱带。为确保高信噪比并防止CCD动态范围过饱和，采用了光谱合并（162个光谱带）和40毫秒（ms）的积分时间，并在两个测试地点收集了斜视高光谱图像（方位视角度为44度和60度）。