Importantly, the standards facilitate measurement comparisons and improved measurement accuracy through identification and reduction of primary sources of uncertainty. GPO Box 858 The standards are transferable to other researchers and applications. It is not just the relflectance of the plants themselves that controls the spectral radiation being emitted from a patch of ground, also having an effect: The reflectance of the soil beneath the plants; Solar and sensor elevation ; Examples of spectral signatures for soils, litter, and vegetation are shown in Figure 11.4.In the case of vegetation, light absorption by leaf pigments dominates the reflectance spectrum in the visible region (400–700 nm). A synthesis of data on spectral properties, vegetation types, growth and energy conditions provides valuable information about biomass and productivity. The standards described here were developed to provide a consistent and repeatable method for recording spectra that minimises the influence of extraneous factors in spectral reflectance, radiance and irradiance measurements. This information is stored and available for data retrieval through the SSD Spectral Database. 1.1 Electroma9netic radiation Various ranges of wavelength of electromagnetic radiation (EMR) make up the electromagnetic spectrum. Spectral properties of plants have been utilized in the context of their usefulness in studying vegetation from remote sensing platforms. Water has high absorption and virtually no reflectance in near infrared wavelengths range and beyond. Turbid water has a higher reflectance in the visible regio… This report focuses on the standards for reflectance spectral measurement developed by the Supervising Scientist Division (SSD). The method considers the factors affecting spectral data (outlined in Pfitzner et al 2005) and provides standards to collect time series spectra of vegetation that maximise the spectral response of the end member itself (Pfitzner & Carr 2006, Pfitzner et al 2006). Some of these factors are dependent on the experimental design. Spectral reflectance signatures result from the presence or absence, as well as the position and shape of specific absorption features, of the surface. A literature review of the factors affecting in situ spectral measurements was undertaken to define what equipment needed to be calibrated, what features needed to be characterised, how the equipment should be calibrated, how the features should be characterised and how the required measurement accuracy could be obtained. A detailed description of the measurement process developed to collect reference spectra and ancillary metadata is then given. The data collected to date will result in a knowledge base far greater than that ever obtained for vegetation spectra with respect to the range of species sampled, the frequency of sampling, duration of sampling, and method and metadata documentation. Spectral Reflectance of Vegetation The spectral characteristics of vegetation vary with wavelength. The collection of ground-based radiance, irradiance and reflectance spectra is a critical and common exercise for many environmental applications. with vegetation canopies. image source: seos-project.eu The rationale for spectral vegetation indices (SVIs) is to exploit the unique spectral signature of green vegetation as compared to spectral signatures of other earth materials (Figure 4.04). Plants that are stressed or diseased can also be identified by their distinct spectral signatures. Importantly, metadata describing what was measured, how the measurement was taken and what the conditions were like during spectral measurement must accompany the spectral data. Figure 3: Reflectance of Vegetation at different wavelength and comparison with Soil and Water. I have browse the internet for the spectral signature for different condition. While many field spectral campaigns may be undertaken, the effort expended in ground-based spectral collection is often only applicable to a single point and time. The sample size and times series of spectra must be appropriate. However, there are no national or international standards for the collection of in situ spectral data. Also, further reports will detail other aspects of the project such as soil spectral measurements made in the laboratory. It is envisaged that this report provides not only a reference manual for spectral measurements but will also play a key role in enabling data comparisons by ensuring the quality, consistency and portability of spectral signature measurements. Whilst spectral data can be acquired quickly in the field, the acquisition and recording of spectral metadata does increase the time required for the field campaign.