Showing papers on "VNIR published in 2004"

Detecting sugarcane ‘orange rust’ disease using EO-1 Hyperion hyperspectral imagery

Abstract: This Letter evaluates several narrow-band indices from EO-1 Hyperion imagery in discriminating sugarcane areas affected by ‘orange rust’ (Puccinia kuehnii) disease. Forty spectral vegetation indices (SVIs), focusing on bands related to leaf pigments, leaf internal structure, and leaf water content, were generated from an image acquired over Mackay, Queensland, Australia. Discriminant function analysis was used to select an optimum set of indices based on their correlations with the discriminant function. The predictive ability of each index was also assessed based on the accuracy of classification. Results demonstrated that Hyperion imagery can be used to detect orange rust disease in sugarcane crops. While some indices that only used visible near-infrared (VNIR) bands (e.g. SIPI and R800/R680) offer separability, the combination of VNIR bands with the moisture-sensitive band (1660 nm) yielded increased separability of rust-affected areas. The newly formulated ‘Disease–Water Stress Indices' (DWSI-1=R800/R...

Lithologic mapping with multispectral ASTER TIR and SWIR data

Abstract: ASTER, launched in December, 1999, composed of three subsystems, each of which multispectrally observes the reflected or emitted radiation from the surface of the earth to space in VNIR (visible and near infrared), SWIR (shortwave infrared) and TIR (thermal infrared) wavelength regions, respectively. ASTER-VNIR has three spectral bands with a spatial resolution of 15m, and the one of which in near infrared has an along track stereo observation capability to produce high quality Digital Elevation Model (DEM). ASTER-SWIR has six spectral bands with a spatial resolution of 30m, which are mainly designed for discriminating altered minerals bearing hydroxyl group. ASTER-TIR has five spectral bands with a spatial resolution of 90m, which presents us a powerful tool for identifying quartz and carbonate minerals as well as discriminating types of silicate rocks. The author have successfully developed a robust method for detecting quartzite and carbonate rocks as well as classifying type of igneous rocks with ASTER TIR data without atmospheric corrections (Level-1B data). Here in this paper, reflectance spectra of minerals in SWIR region measured in the laboratory are analyzed to define calcite index, OH-bearing silicate index, kaolinite index and alunite index for discriminating each mineral by ASTER-SWIR. The defined indices are applied to SWIR data of ASTER Level-1B radiance at the sensor data observing Cuprite area in Nevada, USA, and the discussions are made on the results by comparing the well-known geology of the area. Also, the result of calcite index is compared with the result of applying well-characterized carbonate index defined for ASTER-TIR to clarify the strong point of each index.

Analysis of VNIR (400–1100 nm) spectral signatures for estimation of soil organic matter in tropical soils of Thailand

Abstract: The widely available laboratory spectrometers detect targets at spectral regions restricted to visible and near-infrared (VNIR). The spectral response of soils in this region is predominantly featureless and obstructs the exploitation of absorption features as diagnostic criterion. In this study, polynomial based modelling was developed as an alternative method of estimating soil organic matter (OM) from VNIR spectral region. Forty-one core samples, collected from Lop Buri, Thailand, were subjected to chemical and radiometric analysis. Computations were made across four categories of synthesized bandwidths. The selection procedure identified bands at 960, 1100 and 520 nm as OM sensitive. The widening interval of bandwidth has corresponded with diminishing predictive power, termed ‘bandwidth decay effect’. The use of polynomial models and their validations showed a higher performance than the analysis made with multiple regressions analysis. The polynomial based approach offers a fresh opportunity for mode...

Vicarious calibration of Terra ASTER, MISR, and MODIS

Abstract: The Advanced Spaceborne Thermal Emission and Reflection and Radiometer (ASTER), Multi-angle Imaging Spectroradiometer (MISR) and Moderate Resolution Imaging Spectroradiometer (MODIS) are all onboard the Terra platform. An important aspect of the use of MODIS, and other Earth Science Enterprise sensors, has been the characterization and calibration of the sensors and validation of their data products. The Remote Sensing Group at the University of Arizona has been active in this area through the use of ground-based test sites. This paper presents the results from the reflectance-base approach using the Railroad Valley Playa test site in Nevada for ASTER, MISR, and MODIS and thus effectively a cross-calibration between all three sensors. The key to the approach is the measurement of surface reflectance over a 1-km 2 area of the playa and results from this method shows agreement with MODIS to better than 5%. The paper examines biases between ASTER and the other two sensors in the VNIR due to uncertainties in the onboard calibrator for ASTER and in the SWIR due to an optical crosstalk effect.

APEX; current status of the airborne dispersive pushbroom imaging spectrometer

Abstract: Recently, a joint Swiss/Belgian initiative started a project to build a new generation airborne imaging spectrometer, namely APEX (Airborne Prism Experiment) under the ESA funding scheme named PRODEX. APEX is a dispersive pushbroom imaging spectrometer operating in the spectral range between 380 - 2500 nm. The spectral resolution will be better then 10 nm in the SWIR and < 5 nm in the VNIR range of the solar reflected range of the spectrum. The total FOV will be ± 14 deg, recording 1000 pixels across track with max. 300 spectral bands simultaneously. APEX is subdivided into an industrial team responsible for the optical instrument, the calibration homebase, and the detectors, and a science and operational team, responsible for the processing and archiving of the imaging spectrometer data, as well as for its operation. APEX is in its design phase and the instrument will be operationally available to the user community in the year 2006.

CRISM (Compact Reconnaissance Imaging Spectrometer for Mars) on MRO (Mars Reconnaissance Orbiter)

Abstract: CRISM (Compact Reconnaissance Imaging Spectrometer for Mars) is a hyperspectral imager that will be launched on the MRO (Mars Reconnaissance Orbiter) spacecraft in August 2005. MRO’s objectives are to recover climate science originally to have been conducted on the Mars Climate Orbiter (MCO), to identify and characterize sites of possible aqueous activity to which future landed missions may be sent, and to characterize the composition, geology, and stratigraphy of Martian surface deposits. MRO will operate from a sun-synchronous, near-circular (255x320 km altitude), near-polar orbit with a mean local solar time of 3 PM. CRISM’s spectral range spans the ultraviolet (UV) to the mid-wave infrared (MWIR), 383 nm to 3960 nm. The instrument utilizes a Ritchey-Chretien telescope with a 2.12° field-of-view (FOV) to focus light on the entrance slit of a dual spectrometer. Within the spectrometer, light is split by a dichroic into VNIR (visible-near-infrared, 383-1071 nm) and IR (infrared, 988-3960 nm) beams. Each beam is directed into a separate modified Offner spectrometer that focuses a spectrally dispersed image of the slit onto a two dimensional focal plane (FP). The IR FP is a 640 x 480 HgCdTe area array; the VNIR FP is a 640 x 480 silicon photodiode area array. The spectral image is contiguously sampled with a 6.6 nm spectral spacing and an instantaneous field of view of 61.5 μradians. The Optical Sensor Unit (OSU) can be gimbaled to take out along-track smear, allowing long integration times that afford high signal-to-noise ratio (SNR) at high spectral and spatial resolution. The scan motor and encoder are controlled by a separately housed Gimbal Motor Electronics (GME) unit. A Data Processing Unit (DPU) provides power, command and control, and data editing and compression. CRISM acquires three major types of observations of the Martian surface and atmosphere. In Multispectral Mapping Mode, with the gimbal pointed at planet nadir, data are collected at frame rates of 15 or 30 Hz. A commandable subset of wavelengths is saved by the DPU and binned 5:1 or 10:1 cross-track. The combination of frame rates and binning yields pixel footprints of 100 or 200 m. In this mode, nearly the entire planet can be mapped at wavelengths of key mineralogic absorption bands to select regions of interest. In Targeted Mode, the gimbal is scanned over ±60° from nadir to remove most along-track motion, and a region of interest is mapped at full spatial and spectral resolution. Ten additional abbreviated, pixel-binned observations are taken before and after the main hyperspectral image at longer atmospheric path lengths, providing an emission phase function (EPF) of the site for atmospheric study and correction of surface spectra for atmospheric effects. In Atmospheric Mode, the central observation is eliminated and only the EPF is acquired. Global grids of the resulting lower data volume observation are taken repeatedly throughout the Martian year to measure seasonal variations in atmospheric properties.

Spectral quality metrics for VNIR and SWIR hyperspectral imagery

Abstract: Current image quality approaches are designed to assess the utility of single band images by trained image analysts. While analysts today are certainly involved in the exploitation of spectral imagery, automated tools are generally used as aids in the analysis and offer hope in the future of significantly reducing the timeline and analysis load. Thus, there is a recognized need for spectral image quality metrics that include the effects of automated algorithms. We have begun initial efforts in this area through the use of a parametric modeling tool to gain insight into parameter dependence on system performance in unresolved object detection applications. An initial Spectral Quality Equation (SQE) has been modeled after the National Imagery Interpretation Rating Scale General Image Quality Equation (NIIRS GIQE). The parameter sensitivities revealed through the model-based trade studies were assessed through comparison to analogous studies conducted with available data. This current comparison has focused on detection applications using sensors operating in the VNIR and SWIR spectral regions. The SQE is shown with key image parameters and sample coefficients. Results derived from both model-based trade studies and empirical data analyses are compared. Extensions of the SQE approach to additional application areas such as material identification and terrain classification are also discussed.

Cloud shadow detection: VNIR-SWIR

Abstract: Systems, computer-readable media, and systems are provided for determining whether a data point indicates a presence of a shadow-covered ground point. A data point from top of atmosphere data from an imaging study of an area potentially covered by a cloud shadow is selected. At least one spectral data measurement associated with the data point, the spectral data measurement including at least one of visible, near-infrared, and short wavelength infrared data is taken. At least one of the spectral data measurement and derived spectral index is compared with a spectral data threshold, the spectral data threshold delineating between a shadow-covered ground point and a non-shadow-covered ground point. The data point is classified as one of a shadow-covered ground point and a non-shadow covered ground point based on the comparison with the spectral data threshold.

System design of the CRISM (compact reconnaissance imaging spectrometer for Mars) hyperspectral imager

Abstract: CRISM (Compact Reconnaissance Imaging Spectrometer for Mars) is a hyperspectral imager that will be launched on the MRO (Mars Reconnaissance Orbiter) in August 2005. The MRO will circle Mars in a polar orbit at a nominal altitude of 325 km. The CRISM spectral range spans the ultraviolet (UV) to the mid-wave infrared (MWIR), 400 nm to 4050 nm. The instrument utilizes a Ritchey-Chretien telescope with a 2.06o field of view (FOV) to focus light on the entrance slit of a dual spectrometer. Within the spectrometer light is split by a dichroic into VNIR (visible-near infrared) (λ ≤ 1.05 μm) and IR (infrared) (λ ≥ 1.05 μm) beams. Each beam is directed into a separate modified Offner spectrometer that focuses a spectrally dispersed image of the slit onto a two dimensional focal plane (FP). The IR FP is a 640 x 480 HgCdTe area array; the VNIR FP is a 640 x 480 silicon photodiode area array. The spectral image is contiguously sampled with a 6.55 nm spectral spacing and an instantaneous field of view of 60 μradians. The orbital motion of the MRO pushbroom scans the spectrometer slit across the Martian surface, allowing the planet to be mapped in 558 spectral bands. There are four major mapping modes: A quick initial multi-spectral mapping of a major portion of the Martian surface in 59 selected spectral bands at a spatial resolution of 600 μradians (10:1 binning); an extended multi-spectral mapping of the entire Martian surface in 59 selected spectral bands at a spatial resolution of 300 μradians (5:1 binning); a high resolution Target Mode, performing hyperspectral mapping of selected targets of interest at full spatial and spectral resolution; and an atmospheric Emission Phase Function (EPF) mode for atmospheric study and correction at full spectral resolution at a spatial resolution of 300 μradians (5:1 binning). The instrument is gimbaled to allow scanning over ±60° for the EPF and Target modes. The scanning also permits orbital motion compensation, enabling longer integration times and consequently higher signal-to-noise ratios for selected areas on the Martian surface in Target Mode.

Inspecting MIVIS capability to retrieve chemical-mineralogical information: evaluation and analysis of VNIR-SWIR data acquired on a volcanic area

Abstract: This work is a contribution to the assessment of MIVIS (Multi-spectral Infrared and Visible Imaging Spectrometer) airborne imaging spectrometer capability in applications of surface characterization. The focus is on the visible and near-infrared–short wave infrared (VNIR–SWIR) spectral region, using a dataset acquired in 1994 on Vulcano Island (Italy), to retrieve chemical–mineralogical information on the altered deposits related to volcanic activity. The main processing steps include data quality evaluation in terms of signal-to-noise ratio, atmospheric and topographic corrections and spectral interpretation of the image. Estimation of surface reflectance is based on atmospheric modelling by MODTRAN3.5 and 6S radiative transfer codes. Representative MIVIS reflectance spectra of the main surface units are compared with spectra measured in the laboratory on field samples, and interpreted to characterize the mineralogy on the basis of their spectral features. A thematic map of the main alteration units is t...

Calibration Methodology for the Airborne Dispersive Pushbroom Imaging Spectrometer (APEX)

Abstract: APEX is a dispersive pushbroom imaging spectrometer operating in the spectral range between 380 - 2500 nm. The spectral resolution will be better than 10 nm in the SWIR and < 5 nm in the VNIR range of the solar reflected range of the spectrum. The total FOV will be ± 14 deg, recording 1000 pixels across track with about 300 spectral bands simultaneously. A large variety of characterization measurements will be performed in the scope of the APEX project, e.g., on-board characterization, frequent laboratory characterization, and vicarious calibration. The retrieved calibration parameters will allow a data calibration in the APEX Processing and Archiving Facility (PAF). The data calibration includes the calculation of the required, time-dependent calibration coefficients from the calibration parameters and, subsequently, the radiometric, spectral and geometric calibration of the raw data. Because of the heterogeneity of the characterization measurements, the optimal calibration for each data set is achieved using a special assimilation algorithm. In the paper the different facilities allowing characterization measurements, the PAF and the new data assimilation scheme are outlined.

Sub-visible cloud cover assessment: VNIR-SWIR

Abstract: Methods, computer-readable media, and systems are provided for determining whether a data point indicates a presence of a sub-visible cloud using visible near-infrared data and short wavelength infrared data. A data point is selected from an imaging study of an area potentially covered by at least one of visible clouds and sub-visible clouds. A presence of a sub-visible cloud is determined. The determination is made by comparing a cirrus-band reflectance of the data point with a sub-visible cirrus-band reflectance threshold. The data point is classified as a sub-visible cloud point if the cirrus-band reflectance of the data point exceeds the sub-visible cirrus band reflectance threshold.

Synthesis of high-spatial resolution hyperspectral VNIR/SWIR and TIR image data for mapping weathering and alteration minerals in Virginia City, Nevada

Abstract: The Comstock mining district, around Virginia City, Nevada, consists of mostly Miocene volcanic rocks that have been subjected to multiple episodes of hydrothermal alteration, extensional faulting, and mineralization. The distribution of alteration zones is related to the occurrence of precious metal deposits. Also, as a result of past mining activity, tailings that are now distributed throughout the town site contain-abundant Fe-sulfide minerals that weather to form secondary Fe-minerals often linked to acid mine drainage. To support research into both precious metal exploration, and environmental site characterization high spatial resolution (/spl sim/2 m) hyperspectral VNIR/SWIR and TIR images were acquired over Virginia City using the newly-developed airborne imaging spectrometers HyperSpecTIR and SEBASS. Spectral reflectance data from HyperSpecTIR and spectral emissivity data from SEBASS were used to generate maps of important weathering and alteration minerals. Acid-sulfate alteration minerals were found to be zoned locally and weakly constrained by structures. Jarosite was found to be relatively abundant on mine tailings along with minor occurrences of hydrous Mg-Ca-Al sulfates, indicative of pH conditions around 3-5. Finally, minerals that could not be identified uniquely with one spectral range could be identified using a combination of both VNIR/SWIR and TIR hyperspectral image data.

A method for monitoring mine tailings revegetation using hyperspectral remote sensing

Abstract: This paper investigates the use of airborne hyperspectral remote sensing imagery in the 400-nm to 900-nm spectral range for the extraction of information suitable for monitoring mine tailings revegetation. Compact Airborne Spectrographic Imager (CASI) data were acquired over the Copper Cliff mine tailings impoundment area in the VNIR bands during the summers of 1996 and 1998, and Probe 1 data were collected in the VNIR/SWIR bands during the summer of 1999. Endmember fractions of water, lime, fresh and oxidised tailings, low and high photosynthetic vegetation were obtained using constrained linear spectral unmixing. Vegetation fraction, tailings fraction and texture of the vegetation fraction were used in a K-Mean unsupervised classification, which produced the best results using seven classes (78.13% overall accuracy) and captured the vegetation cover from dense homogenous to low density patched cover.

Calibration method for IR channel of dual-band long-range airborne camera

Abstract: A dual band camera for long-range airborne reconnaissance has a large common Cassegrain objective, a beam splitter, VNIR and MWIR channels. Non-uniformity correction (NUC) must be especially accurate in this type of application, due to the low dynamic range of a raw image acquired through tens of kilometers of atmosphere. Accurate calibration of non-uniformity in the MWIR band represents a challenge, because of considerable emissivity of the optics, variable optics temperature, high cos 4 effect, vignetting, complex focal plane geometry, residual misalignment between the exit pupil and the dewar's cold stop, and insertion of a blackbody temperature reference source (TRS) directly in front of the dewar window. The paper describes a special calibration method which overcomes the complexities and achieves high NUC accuracy. The method combines in-laboratory transmissibility measurement with two-stage in-flight periodic calibration. The detector non-uniformity is calibrated in wide signal range. The TRS temperature follows a curve giving linear rise of radiance in time. Inner surface of the pod between the optical windows is used as a uniform source for evaluation of a pattern caused by the optics radiation. This method was successfully implemented in the ElOP long-range oblique photography (LOROP) camera.

Separability of VNIR/SWIR reflectance signatures of prepared soil samples: airborne hyperspectral vs. field measurements

Abstract: To better understand the capabilities of hyperspectral imaging spectrometers, a number of organizations planned and carried out a data collection exercise at a desert site in the southwestern United States. As part of this collection, eight soil 'panels' were constructed; four filled with a coarse gravel/sand mixture and four flled with fine soil. Each set of four panels was prepared to represent two moisture and density conditions: wet versus dry and compacted versus loose. Unlike laboratory soil specimens, which use 'purified' samples, these soil flats contained more variability. They therefore better represented the 'natural' environment that would be viewed by an airborne hyperspectral imaging sensor, while still allowing an experimental study under more controlled conditions. This paper examines how well the eight soil types and conditions can be distinguished based on their VNIR/SWIR reflectance spectra derived from field measurements and from airborne hyperspectral measurements made at nearly the same time. A brief review of the phenomenology of soil reflectance spectra will be given. Based on physical attributes of the soils, some new classification approaches have been developed and were applied to the soil panels. These phenomenological methods include examining contrast in certain broadband features and, based on these, calculating various broadband spectral ratios over subsets of the VNIR/SWIR spectral region. The separability of the reflectance spectra from the eight soil panels were also analyzed by applying the Spectral Angle Mapper (SAM) hyperspectral distance metric to quantify the separations between all pairs of soil types and conditions. Finally, a neural network approach was applied to determine distinguishing features of the spectra. The phenomenological approaches, SAM analyses, and the neural network results will be compared.

Aerosol retrieval over urban areas using spatial regression between V/NIR and MIR Hyperion channels

Abstract: Determination of aerosol optical depth from satellite remote sensing measurements is extremely complex due to the large variability of aerosol optical properties. Significant simplification occurs when measurements are taken over water since the ocean reflection signal can be taken as negligible in the NIR.. Unfortunately, over land, most of the signal can be attributed to ground reflectance. While conventional approaches look for “dark” pixels in an image to isolate aerosols, these pixels are subjected to increased noise. In this paper, we explore the feasibility of a regression approach utilizing correlations between the VNIR and MIR channels to extract the aerosol reflection signal over urban areas. This approach is applied to hyperspectral high resolution Hyperion data where the aerosol reflectance signal is shown to agree very well with coincident Aeronet derived reflectance spectra. Comparisons between the regression technique and dark pixel thresholding clearly exhibit the improvement using regression methods. Finally, practical spatial resolution concerns are explored and specifications of the GOES-R imager are assessed.

Analysis on uncertainty in the MODIS retrieved land surface temperature using field measurements and high resolution images

Abstract: In this paper, a generalized split-window method to derive land surface temperature (LST) from MODIS (Moderate Resolution Imaging Spectroradiometer) data is applied. A major problem in land surface temperature inversion is that there are too many unknown variables, especially for MODIS data which is in low resolution, one pixel is a mixture of several cover types. To analysis the uncertainties of the LST retrieval algorithm based on MODIS images, the field measurements, together with fine resolution images, AMTIS (the airborne multi-angle TIR/VNIR imaging system) data and ASTER (Advanced Spaceborne Thermal Emission and Reflection Radiometer) data have been used

Field Fourier Transform Spectral Imaging Experiment of Sagnac Type Imaging Fourier Transform Spectrometer(IFTS)

Abstract: Spatially Modulation Imaging Fourier Transform Spectrometer(SMIFTS) is an important space remote sensor for research and application. In this paper, a prototype of IFTS based on Sagnac interferometer is introduced. The field Fourier Transform spectral imaging experiment is carried out with the prototype and Fourier Transform image in visible and near infrared(VNIR) region is obtained. By processing and Fourier Transforming interferogram of each pixel, spectral image and pixel spectra is extracted with distinct spctral character.

Remote Sensing of the Haughton Impact Structure (HIS): A Terrestrial Proof of Concept for Using the Remote Sensing of Martian Craters as a Probe of Subsurface Composition

Abstract: Impact cratering is the most widespread geological process in the Solar System. Impact craters can provide 'windows' into the subsurfaces of planetary bodies through excavation and uplift. By utilizing remote methods in the visible and near infrared (VNIR; 0.4-1.4 micron), short-wavelength infrared (SWIR; 1.4-2.5 micron) and thermal infrared (TIR 7-14 micron), subsurface mineral compositions may be identified and mapped via impact craters. Complex craters in particular, expose minerals from both the shallow and deep-seated subsurface, which may be identified spectroscopically. Complex craters have morphological features such as central peaks or peak rings, which are composed of relatively coherent lithologies tapped from deep-seated crustal components. While near-surface crustal components can be observed as coherent rocks uplifted and exposed in the rim and the crater walls, and from the ejecta deposits. Only two previously published studies using this approach have been successful on large planetary bodies. Tompkins and Pieters utilized ultraviolet and VNIR from Clementine to characterize near- and deep-subsurface materials in and around lunar craters. The work of Ramsey and Wright was the first remote spectroscopic study to successfully identify near-subsurface materials in the ejecta and crater wall of a terrestrial impact structure, namely Meteor Crater. Here we present early results of a third such study, a remote spectroscopy evaluation of the Haughton impact structure (HIS). The purpose of this study is to serve as terrestrial proof of concept that remote visible/infrared spectroscopic methods in this case, analysis of LANDSAT 7 ETM+ and ASTER data of the well-preserved HIS can be utilized in deciphering the subsurface composition of planetary crusts. This technique is particularly promising for Mars were limited tectonic uplift and ubiquitous dust-mantling offer few opportunities to access subsurface information.

Development of the WAMS-VNIR Instrument for SPF-II

Abstract: Wide-Angle Multi-Band Sensor-Visible and Near Infrared (WAMS-VNIR) has been developed as an Earth-observation mission instrument for SPF-II. SPF-II is a step toward the realization of Stratospheric Platform (SPF) using airships; it is capable of station-keeping flight at an altitude of 4km. WAMS-VNIR is a STARING multi-spectral imaging radiometer and polarimeter with five bands in wavelengths of 500 to 1000nm. WAMS-VNIR has optics of a 110° FOV, two rotating filter wheels, and a 1280 × 1024 pixel Si-CCD FPA. The wide field-of-view optics enable observing an 8km area even from an altitude of 4km. Five narrow-band spectral filters are installed on a rotating wheel, and two polarizers are installed on another rotating wheel. The polarizers rotate around the optical axis separately from the rotation of the wheel, providing several advantages in polarization measurement. The sensor system was completed and performance checks are being conducted. This paper introduces the sensor system and its performance.

Multilook scene classification with spectral imagery

Abstract: Scene classification using multiple views for an urban/rural scene was studied. Visible/Near Infrared (VNIR) imagery was acquired over Fresno, Ca, on July 13, 2003 using the 4-color Quickbird multi-spectral imager. Four scenes were acquired at view angles of +60, nadir, -45, and -60 degrees on a descending pass. Bi-directional reflectance function (BDRF) effects were present. Analysis was conducted at 10-meter spatial resolution. Variations in reflectance with view angle aided in the extraction of surface characteristics, and allowed for improved classification accuracy.

Estimate LAI of crops using airborne multi-angular data

Abstract: Usually we use multi-channel image data, such as TM, and empirical relationship, such as NDVI-LAI relation or SR-LAI relation, to estimate LAI. Multi-angular remote sensing data provide more information for canopy structure. This paper presents a method to estimate LAI using multi-angular data and model inversion method. The airborne multi-angular data were acquired by AMTIS (Airborne Multi-angle TIR/VNIR Imaging System), which was a prototype sensor designed by the Institute of Remote Sensing Applications of Chinese Academy of Science. Our study is based on two datasets: one was acquired in Beijing Shunyi in April 11, and the major crop is sparse winter wheat; another was acquired in Haerbin in August 24, and major crops are dense corn and soybean. Both datasets have been geometrically atmospherically corrected. Ground based measurements were carried out during the flight experiment. SAIL model is chosen to predict reflected radiance of a presumed LAI. Various view angles relate to the different components ratio in view field, and the reflected radiance is different accordingly. Hence, a certain LAI value was given, SAIL model predicts a set of reflected radiances of various angles. We compare the model predict radiance with the radiance viewed by an multi-angular sensor, to find the optimized LAI which can make the radiance predicted by the model be closest to the viewed radiance, then take this LAI value as the right value

Comprehensive rock-type classification by ASTER data over the Ethiopian Rift Valley

Abstract: Space-borne optical remote sensor, ASTER instrument, has VNIR, SWIR and TIR bands and stereo capability. The author had made a preliminary study for the Ethiopian Rift Valley by using only TIR data by his previous paper[11]. In this study, more comprehensive study for geologic interpretation is performed by using all the VNIR, SWIR and TIR, and the topographic information extracted from along track stereo pair data.

A study on the potential of reflectance spectra to determine the chemical components in soils

Abstract: This research focused on some soil samples in Jiang Su province, China. We have got the total ion content including Cu, Pb, Zn, Hg, As and Cd chemical components of these samples. At the same time, soil reflectance spectra in the visible-near infrared region (VNIR) were measured in the laboratory. A multivariate calibration procedure using partial least squares (PLS) regression was applied to establish a relationship between reflectance spectra in the visible-near infrared region and the chemical components. Results showed that hyperspectral remote sensing has the potential to the survey of metal concentrations in soils

Thermal inversion based on separating the radiance contribution of atmosphere and land surface

Abstract: For thermal inversion, observations of TIR are usually used to generate land surface temperature (LST) and atmosphere thermal and moisture profiles. Observations of VNIR are regarded as with little relationship with thermal parameters, as a result, few people use VNIR in thermal inversion. Zhao first used VNIR in thermal inversion and proved that VNIR data is helpful in thermal inversion. However, for land surface researchers, land surface temperature (LST) plays an important role in many applications. A physical algorithm based on quasi-Newton iteration is used on the retrieval of LST. We combined SAS (separation of land surface and atmospheric contribution) algorithm and the physical algorithm, which retrieved LST and atmosphere parameters based on pixel together. In this way, a new algorithm with both microcosmos (pixel) and macroscopy (image) considered is proposed in the paper. The retrieved result showed that the precision of LST retrieval is much higher than the result with original observations