MAPPING THE STRUCTURE OF THE SOIL COVER OF THE TAIGA FROM REMOTE SENSING IMAGERY

An experiment is described in which multiscalar remote sensing imagery is sequentially employed in the detection of various rankings of soil types endemic to the taiga natural zone in the northern USSR. Relief features, vegetation associations, extent of surface water, and drainage patterns visible on imagery at scales from 1:12,000,000 to 1:5,000, also examined at low altitude and in the field at a series of test sites, served as indicators of various soil cover types. Considerable attention is given to an explanation of why these features can be considered valid indicators of taiga soil types as well as to the appearance of the indicators on band-specific (black-and-white) and color composite imagery. Translated from: Izvestiya Akademii Nauk SSSR, seriya geograficheskaya, 1987, No. 3, pp. 87-99.     

ESTIMATES OF THE SENSITIVITY OF COMBINATIONS OF SPECTRAL RADIANCE COEFFICIENTS TO PROPERTIES OF THE VEGETATION COVER

A method is proposed for the calculation, based on the Goudriaan model, of estimates of various combinations of spectral radiance coefficients P_i which are optimal for interpretation of soil color and moisture, vegetation cover density, above-ground reserves of phytomass, and color and orientation of phytoelements. These estimates correspond rather closely with actual measurements obtained from the field. Translated from: Vestnik Moskovskogo Universiteta, geografiya, 1986, No. 4, pp. 75-79.     

多样地表和大气状况下的MODIS数据云检测

云覆盖作为天气和气候变化的一个重要因子,对地表-大气能量平衡和水循环有着重要的影响,因此,快速、准确地利用卫星遥感技术检测云覆盖具有重要的实用价值和科学意义。利用卫星遥感数据,尤其是常用的Moderate Resolution Imaging Spectroradiometer(MODIS)影像数据,因其具有较高的光谱和时间分辨率,以及2330 km扫描幅宽,为大范围实时、准确地进行云检测提供了可能。目前,基于MODIS数据发展了大量的云检测方法,但因地表类型的多样性和大气状况(如空气污染和沙尘事件等)的复杂性,目前已有的云检测方法,检测精度通常具有较大的不确定性,且针对不同地表和大气状况缺乏普适性,同时也缺乏对检测精度的定量化评估。因此,本文首先比较了常用的3种云检测算法,并基于前人经验提出了两种改进方法(方法4和方法5),首先区分出云和冰雹,摒弃了不稳定的亮温波段,两种算法均适用于复杂地表和大气状况的云检测算法。结果显示,方法5可以较好地应用于基于MODIS数据的云检测,总体精度达92.6±7%,改进了现有基于MODIS数据的云检测算法;方法4平均总体精度82.9±13%,虽然精度相对较低,但云残留少,适合作为对云敏感度高的研究工作的云检测方法。     

COLOR SYNTHESIS OF MULTISPECTRAL IMAGERY FOR MAPPING PURPOSES

The authors describe common Soviet practice in the making of false-color composite imagery for visual interpretation. Also addressed are standard image interpretation techniques: figure-ground color contrast, color separation (number of color gradations occurring within an average contrast range), and so-called landscape indicator techniques. Related issues, such as selection of spectral bands and filters for specific interpretation tasks, and the changing reflectance characteristics of band-specific intermediate images, receive attention as well. Tables and figures illustrating relationships between photographic contrast, film contrast ratings, optical densities, and spectral bands are included. Translated from: Geodeziya i kartografiya, 1985, No. 4, pp. 41-46.     

A combined spectral and object-based approach to transparent cloud removal in an operational setting for Landsat ETM+

The automated cloud cover assessment (ACCA) algorithm has provided automated estimates of cloud cover for the Landsat ETM+ mission since 2001. However, due to the lack of a band around 1.375 μm, cloud edges and transparent clouds such as cirrus cannot be detected. Use of Landsat ETM+ imagery for terrestrial land analysis is further hampered by the relatively long revisit period due to a nadir only viewing sensor. In this study, the ACCA threshold parameters were altered to minimise omission errors in the cloud masks. Object-based analysis was used to reduce the commission errors from the extended cloud filters. The method resulted in the removal of optically thin cirrus cloud and cloud edges which are often missed by other methods in sub-tropical areas. Although not fully automated, the principles of the method developed here provide an opportunity for using otherwise sub-optimal or completely unusable Landsat ETM+ imagery for operational applications. Where specific images are required for particular research goals the method can be used to remove cloud and transparent cloud helping to reduce bias in subsequent land cover classifications.     

THE STUDY OF SOIL-VEGETATION DYNAMICS THROUGH REMOTE SENSING

Remote sensing imagery at widely varying scales is used in the analysis of the soil-vegetation cover of the west-central Siberia. Space imagery and smaller-scale air photographs initially are used to divide a study area into basic soil-vegetation complexes based on the criterion of figure outline. The internal structure of the complexes are then analyzed in greater detail, using larger-scale air photographs and a standard interpretation key based on selected field observations. Tonal-textural variations establish the ecological affiliations of separate elements within each complex and their dynamic states at a particular point in time. Translated from: Geografiya i prirodnyye resursy, 1985, No. 2, pp. 112-119.     

USE OF SATELLITE IMAGERY IN ESTIMATING THE MOISTURE CONDITION OF SNOW COVER

A method for determining areas of most intensive melting within a mountain snowpack is described, based on an inverse relationship between reflectance and age of snow at wavelengths greater than 0.8 μm. Comparisons between the area of snow cover detected on visible and near infrared satellite imagery at different times during the spring thaw, and more specifically differences in position of the snowline, permit identification of the upper boundary of a zone of intensive snow-melt and water discharge from the snow cover. Translated from: Distantsionnyye Issledovaniya rel'yefa Sibiri, A. L. Yanshin and V. N. Sharapov, eds. Novosibirsk: Nauka, 1985, pp. 88-91.     

国产高分辨率遥感卫星影像自动云检测

云检测一直是卫星影像处理的难题,特别是混有地物光谱特性的薄云长期成为影像产品生产的阻碍。本文所介绍的国产高分辨率遥感卫星影像自动云检测方法能够有效克服这一难题。首先采用改进的颜色转换模型,将影像由RGB转换至HIS颜色空间,利用影像强度信息与饱和度信息生成基底图,并使用影像近红外与色调信息对其进行优化,生成修正图。然后利用直方图均衡化与双边滤波结合带限定条件的Otsu阈值分割提取纹理信息,并对修正图进行误差剔除生成云种子图。最后以HIS颜色空间的强度信息为向导,结合云种子图进行云精确提取。与不同自动、人工交互式云检测方法相比,总体精度提高了10%左右,并且能够较好地提升云检测效率。     

INTERPRETATION OF STORM SURGES AND RELATED PHENOMENA ON SPACE IMAGERY

A final paper on water-level monitoring from space outlines principles for the use of space imagery in interpretation of short-term changes in the position of shorelines and coastal water levels resulting from storm surges and strong offshore winds. Over 100 images of various types, seasons, and storm-surge conditions, carefully referenced with field data on slope, vegetation cover, water level, and wind direction, were used to determine “maximal” and “minimal” positions of the Caspian shoreline for the period 1973-1983. This information is useful in understanding the seasonal regime of water-level fluctuations and anticipating flooding associated with winds of a given velocity. Translated from: Izvestlya vysshikh uchebnykh zavedenly, geodeziya i aerofotos'yemka, 1986, No. 4, pp. 93-97.     

MAPPING THE SOILS OF THE MAJOR NATURAL ZONES OF THE USSR FROM REMOTE SENSING IMAGERY

The authors describe the results of their experience in the use of remote sensing imagery to map the distribution of soils within the major natural zones (e.g., wooded steppe, taiga, semidesert) of the USSR. Considerable attention is devoted to instrumental-visual methods of interpretation before the focus shifts to automated interpretation and methods of map compilation, particularly general mapping at intermediate and large scales. One section assesses the relative sizes of mesorelief forms and fields in various natural zones in an effort to determine at what image scales the soil types indicated by these features will be identifiable. Translated by Edward Torrey, Alexandria, VA 22308 from: G. V. Dobrovol'skiy and V. L. Andronikov, eds., Aerokosmicheskiye metody v pochvovedenii i ikh ispol'zovaniye v sel'skom khozyaystve: sbornik nauchnykh trudov [Remote Sensing Methods in Soil Science and Their Utilization in Agriculture: A Collection of Scientific Works]. Moscow: Nauka, 1990, pp. 22-34.     

SATELLITE IMAGERY OF CLOUD COVER IN THE STUDY OF SHORT-WAVE RADIATION AT THE EARTH'S SURFACE

A method is proposed for analyzing properties of solar radiation at the earth's surface based on satellite observations of cloud cover. It is shown that the amount of incident solar radiation is clearly governed by type of weather conditions and, more specifically, by the quantity and types of clouds. This affords a basis for predicting solar radiation receipt at the earth's surface. Translated by Edward Torrey, Alexandria, VA 22308 from: Vestnik Moskovskogo Universiteta, geografiya, 1989, No. 2, pp. 83–85.     

AN INITIAL ATTEMPT AT INTERPRETING THE STRUCTURE OF MOUNTAINOUS AREAS IN THE WESTERN ANTARCTIC WITH SPACE IMAGERY

The second of two reports on the use of space imagery in the interpretation of Antarctica's geologic structure applies interpretation procedures described in an earlier article (see Mapping Sciences and Remote Sensing, 1985, No. 1) to produce a geologic map of a portion of the Antarctic Peninsula. Features identified on space imagery and depicted on the map include: a deep pericratonnal fault zone, a Mesozoic fold belt interrupted by a complex system of faults, and ring or annular structures of volcanic origin. Translated from: Antarktika, AN SSSR Mezhduve-domstvennaya komissiya po izucheniyu Antarktiki, Doklady komissii [USSR Academy of Sciences Joint Commission on Antarctic Research, Commission Report], No. 24. Moscow, 1985, pp. 43-49.     

AERIAL PHOTOGRAPHIC STUDIES OF THE MARINE ECOLOGY OF THE WHITE SEA

Aerial photographic surveys of the White Sea have proven to be an effective means for studying the character of bottom relief and bottom sediments in shallow areas along its coast, particularly when film sensitive to visible radiation in the yellow-green range of the spectrum is used. More specifically, the article discusses methods of aerial photographic surveying, keys for the interpretation of different types of bottom sediments, methods of mapping underwater vegetation from air photos, and the potential of radar imagery for the indirect interpretation of bottom features. Sample interpretation maps from the White Sea are included. Translated by Edward Torrey, Alexandria, VA 22308 from Izvestiya Vsesoyuznogo Geograficheskogo Obshchestva, 1988, No. 4, pp. 314-321.     

Derivation of maximum value composite images using multidate NOAA-AVHRR data

Multidate NOAA-AVHRR Data has been used for monitoring dynamic changes of the vegetation and coastal processes. However, the interpretation of the data is significantly affected by presence of the clouds. An attempt has been made in this paper to evaluate the technical aspects of a processing methodology to generate a cloud masked imagery using multidate NOAA-AVHRR data to minimize cloud cover in the scene. A Maximum Value Composite Image is generated after cloud minimisation. The utility of the technique has been tested in a case study to generate Normalised Difference Vegetation Index (NDVI) over the Indian Subcontinent. The process over two days produced spatially continuous cloud-masked imagery to study green vegetation dynamics. The technique minimizes cloud contamination, reduces off-nadir viewing effects and generates maximum value composite image.     

INTEGRATION OF CARTOGRAPHIC AND REMOTE SENSING METHODS

The history of the joint use of maps and air photos/space imagery in geographic problem solving is examined, as are general problems which must be addressed before more complete consolidation of map use and image interpretation methods will be possible. The relatively new field of geoiconics, encompassing image theory, processing, and interpretation, is proposed as a branch of knowledge promoting the integration of cartography and remote sensing rather than a megafield that will ultimately replace them. Translated from: Geografiya i prirodnyye resursy, 1985, No. 4, pp. 11-22.     

A REMOTE SENSING METHOD FOR DETERMINING HEAT FLUX AT THE OCEAN-ATMOSPHERE BOUNDARY LAYER

Results of experiments in the measurement of heat flux at the ocean-atmosphere boundary layer are described. More specifically, an algorithm is presented for the calculation of the different components of total heat flux (from the ocean into the atmosphere) based on estimates of water temperature, wind velocity, and cloud cover obtained from remote sensing imagery. Use of the algorithm yields values for total heat flux which, when averaged over a ten-day period, are only 10% less accurate than those obtained according to traditional methods (research vessels, buoys, offshore platforms). Translated from: Izvestiya vysshykh uchebnykh zavedeniy, Geodezlya i aerofotos”yemka, 1986, No. 5, pp. 117-120.     

卫星影像的云雾检测及干扰去除

云雾检测及去除是光学遥感图像处理的难题。厚云雾因具高反射特性，可通过阈值的设定将其检测并去除； 薄云因混有地物 光谱特性而较难检测，需先对影像做相对辐射校正处理，再将影像由RGB转换成HIS彩色模型，并假设薄云雾的加入等于白色颜料的加 入，即仅改变光谱的亮度或饱和度值，色相并无改变，藉此，可用多时段方式检测。实践证明，在HIS系统中可简化薄云雾的检测准 则，大大提高自动化检测云雾的可能性。     

VEGETATION AS A CRITERION FOR INTERPRETING THE MOISTURE REGIME OF A LANDSCAPE

Vegetation signatures on aerial photographs and space imagery are used as indicators of soil moisture differences in a Siberian taiga landscape. The authors use remote sensing products to identify all major habitat types resulting from variable soil moisture regimes that were observed on the ground. These types are described, as are their interpretation keys and the effects of scale change on habitat discrimination. Translated from: Kosmicheskiye metody izucheniya prirodnoy sredy Sibiri i Dal'nego Vostoka, Novosibirsk, 1983, pp. 63-74.