THE READABILITY OF THE MAP: THEORETICAL PRINCIPLES

An effort is made at developing a theory of map readability, defined as the process of the user's representation of the information of the map in his/her own mind. This can be estimated quantitatively by surrogate measures, which include the speed of map comprehension and accuracy of map interpretation. Levels of psychological representation of map information are incorporated to determine at what stage particular aspects of map knowledge are understood. Thus what readability entails, and the approaches used to measure it (what types of things are comprehended, how fast, and how accurately) will depend upon the level of representation. Translated from: Vestnik Leningradskogo Universiteta, seriya 7 [geologiya, geografiya], 1988, No. 1, pp. 32-37.     

THE PRESENT STATE OF ECOSYSTEMS IN MONGOLIA: PRINCIPLES OF EVALUATION AND MAPPING

This paper explores how such characteristics as the polarization of reflected radiation, the angular characteristics of its reflectance, and its thermal properties can be used to supplement conventional remote sensing studies of the condition of the vegetation cover. One possible application is clarified by means of an experiment testing the relationship between the degree of polarization of radiation reflected from cultivated cotton fields and the condition of the crop in those fields. Empirical data demonstrate that changes in the geometric structure of (and reflectance from) fields occurs when cultivated plants are subjected to stress (disease or moisture deprivation). Translated by Edward Torrey, Alexandria, VA 22308 from: L. N. Vasil'yev, ed., Kosmicheskiye metody izucheniya biosfery [Remote Sensing Methods in the Study of the Biosphere]. Moscow: Nauka, 1990, pp. 77–82.     

REMOTE SENSING METHODS IN THE STUDY OF SOILS IN BELARUS'

Applications of remote sensing in the study of soils of Belarus' are investigated. The focus is upon ascertaining relationships between phototone of cultivated soils and various soil characteristics (humus content, texture, etc.); upon ensuring the best times for imaging; on the revision of existing soil maps from remote sensing imagery; and on determinations of humus content from spectral reflectance values. 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. 109–116.     

DIGITAL PROCESSING OF REMOTE SENSING IMAGERY IN SOIL MAPPING

The authors describe strategies for the utilization of digital image processing in the compilation of soil maps at scales of 1:1,000,000 and 1:25,000 for the trans-Volga region of Russia. Particular attention is devoted to an exploration of the effects of variations in soil humus content, texture, and degree of erosion upon spectral brightness coefficients. Results of the mapping demonstrate the promise of digital image processing in the differentiation of a number of chernozem soil subtypes. Translated by Edward Torrey, Alexandria, VA 22308 from: 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. 214–225.     

利用RD模型和DEM数据的高分辨率机载SAR图像模拟

本文提出一种利用DEM数据基于RD模型的SAR图像模拟方法。该方法选择了Muhleman后向散射系数模型模拟SAR图像的辐射特性,引入SAR成像中的RD模型直接进行几何变换和灰度重采样模拟出SAR图像的几何特征。实验结果分析表明:模拟的SAR图像和真实SAR图像在图像纹理和几何关系上是一致的,而且几何关系可以精确配准到均方根误差为1.3个像素。     

国土资源部内网网站内容建设研究与实践

国土资源部内网网站经过多年的发展,形成了一套完善的内容体系和信息维护机制.本文详解了国土资源部内网网站内容建设原则、总体架构、信息分类、栏目规划、维护模式等,总结了网站内容建设所取得的成效.     

视觉显著性与知觉组织相结合的高分影像居民地提取方法

受人类视觉认知机制的启发,提出了一种利用视觉显著性与知觉组织相结合的高分辨率遥感影像居民地提取方法。首先利用认知物理学中的数据场构建居民地的视觉显著性模型,并通过自适应阈值法实现候选居民地的自动提取,然后利用多尺度小波变换的高频特征实现居民地的知觉组织,最后通过集合交运算提取同时满足这两种视觉机制的居民地。通过ZY-3和Quickbird两种高分传感器的影像数据集进行居民地提取试验,验证了该方法的有效性。     

GLONASS phase bias estimation and its PPP ambiguity resolution using homogeneous receivers

Integer ambiguity resolution (IAR) appreciably improves the position accuracy and shortens the convergence time of precise point positioning (PPP). However, while many studies are limited to GPS, there is a need to investigate the performance of GLONASS PPP ambiguity resolution. Unfortunately, because of the frequency-division multiple-access strategy of GLONASS, GLONASS PPP IAR faces two obstacles. First, simultaneously observed satellites operate at different wavelengths. Second and most importantly, distinct inter-frequency bias (IFB) exists between different satellites. For the former, we adopt an undifferenced method for uncalibrated phase delay (UPD) estimation and proposed an undifferenced PPP IAR strategy. We select a set of homogeneous receivers with identical receiver IFB to perform UPD estimation and PPP IAR. The code and carrier phase IFBs can be absorbed by satellite wide-lane and narrow-lane UPDs, respectively, which is in turn consistent with PPP IAR using the same type of receivers. In order to verify the method, we used 50 stations to generate satellite UPDs and another 12 stations selected as users to perform PPP IAR. We found that the GLONASS satellite UPDs are stable in time and space and can be estimated with high accuracy and reliability. After applying UPD correction, 91 % of wide-lane ambiguities and 99 % of narrow-lane ambiguities are within (?0.15, +0.15) cycles of the nearest integer. After ambiguity resolution, the 2-hour static PPP accuracy improves from (0.66, 1.42, 1.55) cm to (0.38, 0.39, 1.39) cm for the north, east, and up components, respectively.     

Assessment of PPP integer ambiguity resolution using GPS,GLONASS and BeiDou (IGSO,MEO) constellations

Although integer ambiguity resolution (IAR) can improve positioning accuracy considerably and shorten the convergence time of precise point positioning (PPP), it requires an initialization time of over 30 min. With the full operation of GLONASS globally and BDS in the Asia–Pacific region, it is necessary to assess the PPP–IAR performance by simultaneous fixing of GPS, GLONASS, and BDS ambiguities. This study proposed a GPS + GLONASS + BDS combined PPP–IAR strategy and processed PPP–IAR kinematically and statically using one week of data collected at 20 static stations. The undifferenced wide- and narrow-lane fractional cycle biases for GPS, GLONASS, and BDS were estimated using a regional network, and undifferenced PPP ambiguity resolution was performed to assess the contribution of multi-GNSSs. Generally, over 99% of a posteriori residuals of wide-lane ambiguities were within ±0.25 cycles for both GPS and BDS, while the value was 91.5% for GLONASS. Over 96% of narrow-lane residuals were within ±0.15 cycles for GPS, GLONASS, and BDS. For kinematic PPP with a 10-min observation time, only 16.2% of all cases could be fixed with GPS alone. However, adding GLONASS improved the percentage considerably to 75.9%, and it reached 90.0% when using GPS + GLONASS + BDS. Not all epochs could be fixed with a correct set of ambiguities; therefore, we defined the ratio of the number of epochs with correctly fixed ambiguities to the number of all fixed epochs as the correct fixing rate (CFR). Because partial ambiguity fixing was used, when more than five ambiguities were fixed correctly, we considered the epoch correctly fixed. For the small ratio criteria of 2.0, the CFR improved considerably from 51.7% for GPS alone, to 98.3% when using GPS + GLONASS + BDS combined solutions.     

Signal acquisition of Luojia-1A low earth orbit navigation augmentation system with software defined receiver

Low Earth Orbit (LEO) satellite navigation signal can be used as an opportunity signal in the case of a Global Navigation Satellite System (GNSS) outage, or as ...