We propose a calculation procedure for obtaining multispectral images in remote sensing of vegetation objects in the spectral range 400-1000 nm, based on three-channel spectral zonal images and reference spectra measured at several points of the recorded scene. The procedure makes it possible to improve the information content of the data for solving various thematic classification problems.Introduction. Differences in the reflectance spectra of objects is the basis for recognition of such objects by optical remote sensing [1][2][3][4][5]. In studies of the Earth's vegetative cover, in particular forests, the possibilities of remote sensing have been far from completely utilized [6,7]. Most work on remote sensing as applied to forests (as for other vegetation stands) is based on data obtained from space vehicles. In a number of publications, the authors rely on data obtained using spectrometers and video spectrometers mounted on airplanes [8][9][10][11] and also on helicopters [7]. The advantages and disadvantages of airborne imaging from aircraft are briefly discussed in [5,7]. In addition, we note that when aircraft are used, the reliability of the classification of types of stands may be very high. Comparison of the results from using images with different spatial resolution [12] showed that images obtained from low altitudes make it possible to determine forest fragmentation and biodiversity at the level of individual treetops (for inventory purposes), while those obtained from high altitudes make it possible to very accurately classify the composition of the vegetation at the landscape level. One more problem in forest monitoring which is also solved more accurately using aircraft is determination and assessment of damage done by forest fires. This problem is important not only from an economic point of view but also from the standpoint of the effect of fires on global ecology, which is more significant than suggested in [13].An advantage of spectral zonal images obtained on board aircraft is their high spatial resolution, generally matching the rather large dimensions of the frame (capture band); a relative disadvantage is the limited set of spectral zones (bands), which may not always convey the specific spectral details of objects on the underlying surface. However, very often three or four channels are enough to achieve good recognition of vegetation [14]. In this case, in contrast to automatic classification based on the spectral characteristics of the image recorded by a hyperspectral camera, here partially interactive processing is required to ensure high accuracy [15, 16]. The correct choice of the channels optimizes the spectral zonal system with respect to the efficiency/cost criterion and is quite important. This choice depends on the objects to be studied (the underlying surfaces) and what needs to be done. The video spectrometric system VSK-2 that we designed and used for studying forests [5,7] is an imageplane scanner. Each frame records "instantaneously"; in contrast to hyperspectral scanners,...

We describe selection of an optical layout and calculation of the spectral sensitivity and measurement uncertainty in a portable spectrometer. The spectrometer is used for transfer of the brightness scale in the 0.4-2.5 μm range from one brightness reference standard to another.Introduction. For remote measurements in the optical range, there is a need for uniform calibration of the energy scales for spectral and multispectral instrumentation [1]. Such calibration is done on metrological test benches, where wide-angle radiation sources (photometric spheres) are used as the working standard for the spectral radiance scale. The exit aperture of such a sphere should span the aperture of the entrance objective lens of the survey system. The diameter of the entrance aperture for survey systems used for remote sensing of the Earth with high spatial resolution reaches 1 m or more. For calibration of such systems, photometric spheres are required with a corresponding size of the exit aperture. Calibration in turn of spheres of diameter ~2 m directly on existing certified metrological test benches is not always possible. The need arises for transfer of the spectral radiance scale from the radiation source of a certified metrological test bench to a large photometric sphere.Comparators are used for calibrating working standards for the spectral radiance scale according to the GOST 8.195-89 scheme [2]. Generally stationary monochromators are used as comparators, such as the MDR-23 with a system for detecting radiation after the exit slit of the monochromator. However, for comparison of spatially separated radiation sources, we need a compact portable spectrometer. With this aim, a portable PVS-02 spectrometer was built at the A. N. Sevchenko Institute of Applied Physical Problems at Belorussian State University (NII PFP BGU) with working spectral range 0.4-2.5 μm. Using the PVS-02, the spectral radiance scale is transferred from a diffuse emitter (photometric sphere with exit aperture 240 mm in the Kameliya-M metrological system) to a photometric sphere with large exit aperture (500-1000 mm). Cooled radiation detectors are used in the PVS-02 to improve the stability and fidelity of reproduction of the spectral radiance scale.Optical Layout of the Spectrometer. A single detector is not capable of providing detection of radiation in the range 0.4-2.5 μm. Two radiation detectors make it possible to completely span the given range: detectors based on silicon and InGaAs. In this case, the need arises to use two polychromators, arbitrarily called the visible range polychromator (VisPoly) and the IR range polychromator (IRPoly).The optical layouts of the visible and IR polychromators are given in Fig. 1. Projection objective lenses focus the light flux from the radiation source onto the entrance slits of the polychromators. The entrance slits of the polychromators are "knife-edge" type. The rotating plane mirrors are designed to deviate the optic axes of the polychromators, with the aim of reducing the external dimensions of the i...

Описується склад і будову блоку оптичних давачів, призначеного для реєстрації просторово-часових розподілів та зображень різних оптичних явищ і ефектів природного та техногенного походження у верхній атмосфері Землі, що розробляється для використання на борту міжнародної космічної станції у рамках космічного експерименту «Діагностика».

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Описуються вимірювання і оптимізація поля зору спектрометричного модуля фотоспектральної системи, що використовується на борту міжнародної космічної станції в рамках космічного експерименту «Ураган». Розглянуто модифіковану оптичну схему із зменшеним полем зору модуля спектрорадіометра в сагітальній площині, а також результати відносної прив'язки цього поля до поля зору модуля реєстрації зображень.