Editorial

This issue of the Journal of Spatial Science includes papers investigating techniques that have direct application such as road median extraction, automatic rooftop extraction, transformation of historic maps into interactive web maps, assessing vacant land as a measure of urban decline, modelling forest characteristics and an interface to visualize large space-time datasets with applications in smart cities. Additionally, research is presented on more fundamental issues such as point generalisation, and receiver code biases and positioning integrity in GNSS. Kumar, Lewis, Cahalane and Peters present the GLIMPSE system to provide a framework for storage, management, accessibility and integration of 3D LiDAR data acquired from multiple platforms. The authors detail a point cloud retrieval approach that provides spatially optimised access to point cloud data for a particular geographic area based on user specifications. With the integrated use of a geospatial database, the GLIMPSE system and point cloud retrieval approach improved the efficiency of road median extraction. Automatic building rooftop extraction is of great importance to many applications including building reconstruction, solar energy supply, and disaster management. The study by B. Wu, S. Wu, Li, J. Wu, Huang, Chen and Yu proposes a building rooftop extraction method using DSM data generated from aerial stereo images and vegetation cover vector data. The proposed method was applied to the centre of Shanghai, China, a typical high density urban area, and experimental results show the method can successfully extract building rooftops. An improved method for generalisation of point features with consideration of reinforcing relationships by Zhang, Yu and Chen aims to preserve global patterns of point cluster during map scaling, an important technique for clear presentation of points in multi-scale maps. Existing methods tend to include single point features ignoring spatial interactions between different types of points, such as different types of facilities that are usually colocated together to reinforce their functions in business. In this respect, generalization of point features should consider not only their own importance but also the reinforcing effects from other nearby features. In the article by Horbiński and Lorek a method for creating an interactive web map of the preindustrial state on the basis of analogue nineteenth-century maps of southern Poland is presented. The main objective is to present a universal scheme that allows transformation of old topographic maps into interactive web maps. The Leaflet library was used as a working environment for programming. Receiver code biases (RCBs) have long been identified as time-constant. However, RCBs can exhibit remarkable intraday variability, that affects GNSS-based ionospheric retrieval and timing applications with different combinations. Ke, Sheng and Wang propose a modified geometry-free GNSS model to extract receiver code bias variations (RCBVs). The experiment collected data at 153 stations to test the MGF model and characterize the JOURNAL OF SPATIAL SCIENCE 2022, VOL. 67, NO. 1, 1–2 https://doi.org/10.1080/14498596.2021.2019971