Orthofoto 2010 Bund – Summer – quasi true – NDVI

The NDVI True Orthophoto is based on ADS80 aerial image stripes from summer 2010. The NDVI (normalised differentiated vegetation index) is the most commonly used vegetation index. It is calculated from Near Infrared – Red/Near Infrared + Red. **Purpose**: The data were obtained by Grün Stadt Zürich for the survey of green flat roofs and green roofing potential in Zurich. The index is based on the fact that healthy vegetation in the visible spectral range (wavelength of about 400 to 700 nm) reflects relatively little radiation in the following near infrared range (wavelength from about 700 to 1 300 nm). The reflection in the near infrared is strongly correlated with the vitality of a plant the more vital the plant, the greater the increase in the degree of reflection in this spectral range. Other surface materials, such as soil, rock or dead vegetation, do not show such a distinctive difference in the degree of reflection of both areas. This circumstance can therefore serve, on the one hand, to distinguish between vegetation-covered areas and also to infer the photosynthetic activity, vitality and density of the vegetation cover.NDVI 正射影像（NDVI True Orthophoto）基于2010年夏季获取的ADS80航空影像条带制作而成。归一化差值植被指数（Normalised Differentiated Vegetation Index，简称NDVI）是目前应用最广泛的植被指数，其计算公式为（近红外波段反射率 - 红波段反射率）/（近红外波段反射率 + 红波段反射率）。 **用途**：该数据集由苏黎世绿色城市部门（Grün Stadt Zürich）采集，用于苏黎世市绿色平顶屋顶及屋顶绿化潜力的调查。 该指数的理论基础为：健康植被在可见光光谱范围（波长约400至700 nm）内的辐射反射量相对较低，而在近红外光谱范围（波长约700至1300 nm）内的反射辐射强度与植物活力高度相关——植物生长活力越强，该光谱区间内的反射率增幅越大。土壤、岩石、枯植被等其他地表物质，在两个光谱区间的反射率差异并不显著。借此，该指数既可用于区分植被覆盖区域与非植被覆盖区域，也可用于推断植被覆盖的光合活性、生长活力及植被密度。