Airborne Multispectral Scanner Data Research Articles

Land surface temperature retrieved from airborne multispectral scanner mid-infrared and thermal-infrared data.

Land surface temperature (LST) is one of the key parameters in the physics of land surface processes at local/global scales. In this paper, a LST retrieval method was proposed from airborne multispectral scanner data comparing one mid-infrared (MIR) channel and one thermal infrared (TIR) channel with the land surface emissivity given as a priori knowledge. To remove the influence of the direct solar radiance efficiently, a relationship between the direct solar radiance and water vapor content and the view zenith angle and solar zenith angle was established. Then, LST could be retrieved with a split-window algorithm from MIR/TIR data. Finally, the proposed algorithm was applied to the actual airborne flight data and validated with in situ measurements of land surface types in the Baotou site in China on 17 October 2014. The results demonstrate that the difference between the retrieved and in situ LST was less than 1.5 K. The bais, RMSE, and standard deviation of the retrieved LST were 0.156 K, 0.883 K, and 0.869 K, respectively, for samples.

Enhancement of bioenergy estimations within forests using airborne laser scanning and multispectral line scanner data

Abstract Forest biomass is a substantial source of renewable energy and is becoming increasingly important due to environmental and economic reasons. In Germany, several studies have assessed the bioenergy potential for large areas, e.g. for an entire Federal state. However, in most cases it was not possible to provide detailed maps showing the biomass and the sustainable energy potential for individual forest stands. Thus, the aim of this study was to develop a new and robust method that provides detailed information regarding the spatial distribution of biomass and forest residues as a potential energy resource using a combination of remotely sensed and in situ data. A case study was carried out in a mixed forest in Southern Germany. First, regression analyses were applied to identify relationships between field measurements with several remote sensing metrics to estimate timber volume, mean stem diameter and age. Cross-validation yielded relative root mean square errors (RMSEs) of 30.20% for volume, 27.92% for diameter and 28.81% for the estimation of the age. The absolute RMSEs were smaller than the standard deviation of the observed variables. Next, the regression equations were used to compute attributes for individual forest stands. Stand attributes were then used to model forest residues. To estimate the sustainable annual potential, the actual harvest volume, as defined by forest management planning, was included in the model. Different model parameters were analyzed and an average potential from 0.993 to 1.181 t ha −1 a −1 was computed. The results were compared to previous studies in Germany.

Remote sensing of snow grain-size and impurities from Airborne Multispectral Scanner data using a snow bidirectional reflectance distribution function model

AbstractAlgorithms to retrieve the snow grain-size and the concentration of snow impurities were developed using a theoretical bidirectional reflectance distribution function (BRDF) model of the snow surface. In this model, snow grains are assumed to be independent spherical ice particles, and the BRDF is calculated with multiple scattering by snow particles. Using these algorithms, the snow grain-size and snow impurities were retrieved from Airborne Multispectral Scanner (AMSS) images at the visible (λ = 0.545 μm) and near-infrared (λ =1.24,1.64 and 2.23 μm) wavelengths observed over the flat snowfield in eastern Hokkaido, Japan, in February 1998. The estimated snow grain-size and impurities were consistent with the results of in situ measurements on the snow surface. For snow grain-size, measured reflectances in the different near-infrared AMSS channels indicated grain-size differences in the vertical profile of the snowpack.

Extraction of smooth cordgrass (spartina alterniflora) biomass and leaf area index parameters from high resolution imagery

High resolution (3 x 3 m) Calibrated Airborne Multispectral Scanner (CAMS) data of Murrells Inlet, S. C. were collected on August 2, 1997. Original CAMS data and various vegetation indices were correlated with in situ a) harvested total above‐ground biomass clippings, and b) leaf‐area‐index (LAI) measurements obtained using a ceptometer. The non‐intrusive in situ LAI measurements were found to be significantly correlated with in situ above‐ground biomass measurements, suggesting that future field sampling of biomass and LAI can be obtained using a ceptometer. Near‐infrared and middle‐infrared bands as well as several vegetation indices were highly correlated with in situ biomass and LAI measurements. The first biomass map of a tidal estuary in South Carolina was produced. The biomass map represents an important base line against which future biomass inventories may be compared.

Development of a method to predict the heat island potential using remote sensing and GIS data

Most studies directed to urban climate simulation have been carried out under the assumption that an urban canopy layer is a sublayer comprised of various roughnesses, and as a consequence, difficulties have arisen in obtaining a suitable heat balance for such a layer. This paper, therefore, focuses on investigating the surface temperature distributions of all urban surfaces via a new index based on sensible heat flux, named the heat island potential (HIP), which can be employed in urban development planning to evaluate the urban thermal environment. Simulation results following the use of HIP are verified by side-looking airborne multi-spectral scanner (MSS) and geographic information system (GIS) data; thereby enabling elucidation of these thermal effects on the atmosphere. In addition, a heat balance algorithm is developed which simulates urban surfaces such that construction of urban thermal images is possible.

二時期航空機ＭＳＳデータを用いた湿原植生分類に有効な観測波長帯の研究

In this study, the number of effective spectral bands and the band combinations were selected to classify the wetland vegetation types using airborne multi spectral scanner data acquired over the Kushiro Mire in June 1992 and August 1993.Effective spectral bands were selected : from June data, from August data, and from data of both months combind. In the method of this process, Jeffries-Matushita (JM) distance was used as a separability measure for 10 wetland vegetation types. Based on the results obtained from these cases, the first three selected effective bands were almost the same : near infrared band (820 to 900nm) which is sensitive to biomass, and two shortwave infrared bands (1520 to 1720nm and 2060 to 2450nm) which are sensitive to water content. To determin the number of effective spectral bands, training sample data were classified by the maximum likelihood method using the selected band combinations. The best classification accuracy was attained by using the 9 bands from combined data.

Front-End Hardware for Recording INS and Altimeter Data in Conjunction with Airborne Multispectral Scanner Data

This paper describes the design and implementation of a hardware interface unit for recording the output from Inertial Navigation System (INS) and Radio Altimeter (RA) (height information) fitted on the Super King Air B 200/300 aircraft. The INS and RA data is recorded on one channel of a high density tape in synchronization with Daedalus Airborne Multispectral Scanner Data which is recorded on the other channels. All recorded data is transferred to Computer Compatible Tapes (CCTs) on a ground conversion system to be used to carry out geometric corrections to the scanner data to generate geocoded products.

Effects of slope morphology on airborne multispectral scanner data

Use of remotely sensed imagery in land use and vegetation classification studies has not always taken into account the effects of topography. Whilst previous work recognises that natural variation in slope and aspect has a deleterious effect on the accuracy of pixel-by-pixel classification based on reflectance values, the cause and effect relationship has yet to be fully accounted for. This study confirms that the variation in topography has an important effect on recorded reflectance values and that such effects are not random but follow direct relationships. These relationships are dependent not only on the wavelength of the reflected radiation and the slope angle and aspect but also the break of slope. Results indicate that even at the microtopographic level, slope morphology has an appreciable effect on reflectance values measured by an airborne scanner.

The relation between reflected radiation and yield on the Broadbalk winter wheat experiment†

Abstract In the classical experiment on Broadbalk field, Rothamsted, winter wheat has been grown continuously under various treatments since 1843. Reflected radiation in red (R) and near-infrared (NIR) wavebands was measured over the field in 1987, twice with an airborne multispectral scanner (MSS) from an altitude of 600m and five times with a muhiband radiometer from 2 m above the crop surface. The normalized difference vegetation index, NDVI= ( NIR−R)/ (NIR + R), was calculated for each date and its relation with harvest yield investigated. The NDVI determined from the airborne MSS data was correlated with yield, and the correlation was found to increase if the variable effect of productivity was introduced into the relationship. The NDVI values calculated from the ground radiometry were more strongly correlated with yield, however. The differences in yield on Broadbalk are caused mainly by the amounts of nitrogen-containing fertilizer applied. The results suggest that the radiation measured by airborn...

The derivation of water volume reflectances from airborne MSS data using in situ water volume reflectances, and a combined optimization technique and radiative transfer model

Abstract Water volume reflectance images of three water cooling reservoirs were derived from airborne Daedalus DS-1260 multispectral scanner (MSS) data using a radiative transfer model to eliminate atmospheric effects and to derive downwell-ing irradiances. Sixty in situ water volume reflectances and the associated sensor and sun geometries were input into the radiative transfer model. Using the radiative transfer model to generate water volume reflectance values at each field site, an optimization procedure minimized the difference between modelled and in situ water volume reflectances resulting in optimized sensor brightness value to radiance conversion gain and bias factors, and optimized surface visual range and mean terrain background reflectance. Subsequently water volume reflectance images were derived at six wavelengths encompassing the blue to near-infrared using the optimized atmospheric parameters and conversion factors as inputs into the radiative transfer model. Modelled reflectance images we...

Selecting a spatial resolution for estimation of per-field green leaf area index

For any application of multispectral scanner (MSS) data, a user is faced with a number of choices concerning the characteristics of the data; one of these is their spatial resolution. A pilot study was undertaken to determine the spatial resolution that would be optimal for the per-field estimation of green leaf area index (GLAI) in grassland. By reference to empirically-derived data from three areas of grassland, the suitable spatial resolution was hypothesized to lie in the lower portion of a 2-18 m range. To estimate per-field GLAI, airborne MSS data were collected at spatial resolutions of 2 m, 5 m and 10 m. The highest accuracies of per-field GLAI estimation were achieved using MSS data with spatial resolutions of 2 m and 5 m.

Classification of Airborne Multispectral Scanner Data for Mapping Current Defoliation Caused by the Spruce Budworm

Abstract Airborne multispectral scanner data were acquired over a mixed fir and spruce forest affected by both current defoliation (red discoloration) and cumulative defoliation (loss of needles) caused by feeding of the spruce budworm (Choristoneura fumiferana [Clem]). The spectral bands, ratios and differences of bands, and principal components derived from the bands were examined for their usefulness for discriminating defoliation condition. Classifications were conducted using the best combinations of two through nine bands or features derived from the bands. Three levels of current defoliation could be classified (heavy, light, and healthy). Cumulative defoliation and mixed-wood areas caused confusions in the classifications. There was little advantage to including more than four bands or derived features in the classifications. For. Sci. 34(2):259-275.

Modeling of Estuarne Chlorophyll a from an Airborne Scanner

Near simultaneous collection of 34 surface water samples and airborne multispectral scanner data provided input for regression models developed to predict surface concentrations of estuarine chlorophyll a. Two wavelength ratios were employed in model development. The ratios werechosen to capitalize on the spectral characteristics of chlorophyll a, while minimizing atmospheric influences. Models were then applied to data previously acquired over the study area thre years earlier. Results are in the form of color-coded displays of predicted chlorophyll a concentrations and comparisons of the agreement among measured surface samples and predictions basedon coincident remotely sensed data. The influence of large variations in fresh-water inflow to the estuary are clearly apparent in the results. The synoptic view provided by remote sensing is another method of examining important estuarine dynamics difficult to observe from in situ sampling alone.

Estimating the Green Leaf Area Index of Grassland with Airborne Multispectral Scanner Data

Remotely sensed radiance recorded in red and near, middle and thermal infrared wavebands is usually correlated with the green leaf area index (GLAI) of a vegetation canopy. Empirical models based upon airborne multispectral scanner data recorded in these wavebands were inverted and the GLAI of grassland was estimated, but to an accuracy of only 18-51% (95% confidence level) for a five-class classification and ± 0.37 ± 0.75 GLAI at a point. Refinement of the methodology by suppression of environmental influences on the remotely sensed data and by allowing for both the asymptote in the empirical model and error in the ground data increased significantly the accuracy of GLAI estimation to 60-88% (95% confidence level) for a five classclassification and ±0.06 ± 0.10 GLAI at a point. It was concluded that future studies of this kind should use red and near infrared radiance; the refined methodology and an improved sampling scheme for the collection of ground data.

Lithological discrimination in central Snowdonia using airborne multispectral scanner imagery†

Abstract An evaluation has been carried out of the use of 11-channel airborne multispectral scanner data as an input to large-scale geological mapping in upland Britain. The optimum index factor (OIF) provides a ranking of possible three-band combinations in terms of their uncorrelated spectral data content, while principal components analysis may be used to compress multi-channel data, thereby minimizing information loss. An assessment of the geological information content of various imagery products concluded that both high-value OIF and principal component images were useful for lithological discrimination of solid and superficial deposits whereas aerial photographs were better for identifying structural features.

Multispectral remote sensing of nearshore suspended sediments: a pilot study

The till that comprises the coastal cliffs at Holderness is being eroded and transported southwards by waves and currents within the nearshore zone. As a first step towards estimating the magnitude of this movement, airborne multispectral scanner data were collected. The spectral radiance ( Lλ ) recorded by this sensor was positively correlated with the suspended sediment concentration ( SSC) at the 95 percent confidence level. However, when the relationships between SSC and Lλ were inverted for the estimation of SSC, errors of the order of 343-494 percent were observed. It is recommended that for future studies there is a need to reduce the errors consequent upon the areal, vertical and temporal variability in SSC, the problems of inversion and the presence of white-caps.

Airborne MSS data to estimate GLAI

Abstract Airborne multispectral scanner ( MSS) data, collected in June 1984, were used to estimate the green leaf area index ( GLAI) for 60 km2 of grassland. The methodology involved (i) radiometric and atmospheric correction, (ii) production of a vegetation index image, (iii) calculation of a calibration relationship between a vegetation index and GLAI, (iv) production of an image of estimated GLAI by inversion of the calibration relationship in (iii), and (v) accuracy assessment. The initial accuracy of GLAI estimation was ± 0-75 GLAI for an area and 17-40 per cent at the 95 per cent confidence level, for a six-class classification. Refinements to the methodology were evaluated by their effect upon the accuracy of GLAI estimation. In order of increasing importance these refinements were: suppression of environmental effects on the remotely sensed data, processing on a per-field rather than a per-pixel basis, calculation of the calibration relationship between a vegetation index and GLAI, using ground-ba...

The application of airborne remote sensing to the detection of solution features in limestone

Abstract Airborne remote sensing techniques have been developed for the detection of collapse and subsidence features in chalk and other limestone rocks. The detection of such features in the early stages of an engineering project is of crucial importance if serious geotechnical problems to building construction and public safety are to be avoided. Particular attention is paid to the potential of airborne multispectral scanner (MSS) and thermal infrared (IR) data as a means of detection. Background information is also provided concerning a project to obtain multitemporal thermal IR data over two test sites on the Cretaceous Chalk outcrop of southern England.

The interactive effect of spatial resolution and degree of internal variability within land-cover types on classification accuracies

Abstract A study is made to assess the effect of spatial resolution on the degree of internal variability within land-cover classes and then to examine how this within-class variance affects classification accuracy. Airborne Multispectral Scanner data flown at 5 m resolution are degraded to simulate 10 and 20 m data. Classification accuracies within internally homogeneous classes are found to be high at all spatial resolutions. In contrast, classification accuracies of land-cover types characterized by a high degree of internal variability or scene noise improve by up to 20 per cent as spatial resolution is coarsened because the proportion of scene noise is reduced. A further improvement in classification can be achieved by smoothing the imagery prior to classification using various spatial filters. The extent of this improvement was found to be as much as 25 per cent depending on the type of spatial filter used, the window size of the filter, the spatial resolution of the data and the land-cover type bei...

Assessing impacts of off-nadir observation on remote sensing of vegetation: use of the Suits model

The use of Suits' (1972a, b) digital radiative transfer model to simulate the effect of nonLambertian canopy reflectance on off-nadir observations of vegetation is discussed. Canopy reflectances of cord grass are calculated using the radiative transfer model, field radiometric measurements, and airborne multispectral scanner data. The effects of varying view angles on canopy reflectance are analyzed and compared. The comparison reveals that the model is effective in simulating the sense and magnitude of reflectance change due to variable angles of observations; however, the model does not reproduce the observed dependence of nadir canopy reflectance on solar zenith angle. It is concluded that the radiative transfer model is applicable for predicting the variation in canopy reflectance due to changing view zenith angles.