Multi-GNSS processing is becoming increasingly important in the location-based world of today. This issue includes the Special Feature: Multi-GNSS processing, positioning and applications. Three world class researchers are Guest Editors for this feature: Robert Odolinski, Peter Teunissen and Baocheng Zhang. The papers represent important contributions to the development of this area of spatial science and the context is explained in the Preface to the Special Feature. Additional papers in this issue include the contribution by El-Mowafy, Cheung and Rubinov on the first results of the next-generation dual-frequency multi-constellation SBAS-based kinematic positioning in Australian urban environments. Kinematic tests were run in scenarios characterised by four environments: high-density urban, low-density urban, suburban and tree-canopy. Li, Sang and Ning investigate a multiscaling-based semi-analytic orbit propagation method for catalogue maintenance of space debris focusing on orbit prediction and orbit determination of space debris. The paper presents a semi-analytic method using a multiscaling technique. The authors indicate computational efficiency of the semianalytic method against numerical methods is improved by about 95 percent. Mineralogical mapping using Landsat-8 OLI, Terra ASTER and Sentinel-2A multispectral data is investigated by Adiri et al. The objective of this research is to evaluate the potential of multispectral Landsat-8 OLI and Sentinel-2A sensors in comparison with the Terra ASTER sensor in mineralogical mapping using band ratio, independent component analysis and mixture tuned matched filtering methods. The final paper in this issue by Jun and Jiansong uses high-resolution remote sensing images and proposes a case classification method through a detailed study and discussion of the construction of a land cover classification case. The research uses Worldview-2 satellite images with 0.5-m spatial resolution and the effectiveness of the proposed method is then verified using the case library.

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社论

多 GNSS 处理在当今基于位置的世界中变得越来越重要。本期包括特刊：Multi-GNSS 处理、定位和应用。三位世界级研究人员是本专题的客座编辑：Robert Odolinski、Peter Teunissen 和 Baocheng Zhang。这些论文对这一空间科学领域的发展做出了重要贡献，其背景在专刊的前言中进行了解释。本期其他论文包括 El-Mowafy、Cheung 和 Rubinov 对澳大利亚城市环境中基于下一代双频多星座 SBAS 的运动学定位的初步结果的贡献。运动学测试在具有四种环境特征的场景中运行：高密度城市、低密度城市、郊区和树冠。李，Sang 和 Ning 研究了一种基于多尺度的半解析轨道传播方法，用于空间碎片目录维护，重点是空间碎片的轨道预测和轨道确定。本文提出了一种使用多尺度技术的半解析方法。作者指出，相对于数值方法，半解析方法的计算效率提高了约 95%。Adiri 等人研究了使用 Landsat-8 OLI、Terra ASTER 和 Sentinel-2A 多光谱数据的矿物学制图。本研究的目的是评估多光谱 Landsat-8 OLI 和 Sentinel-2A 传感器与 Terra ASTER 传感器在矿物学绘图中的潜力，使用频带比、独立成分分析和混合调谐匹配滤波方法。Jun和Jiansong在本期的最后一篇论文使用高分辨率遥感图像，通过对土地覆盖分类案例构建的详细研究和讨论，提出了案例分类方法。该研究使用空间分辨率为 0.5 米的 Worldview-2 卫星图像，然后使用案例库验证所提出方法的有效性。