The September 2022 issue of the Journal of Spatial Science is always an important issue as it includes announcement of the winner of the Best Research Paper Award made by the Journal of Spatial Science Editorial Board. The award is made annually based upon peer reviewed research and review papers published in the twelve-month period from 1 July 2021 to 30 June 2022. Details of the Award are contained in this issue.
Once again, it comes time to farewell one of our valued members of the Editorial Board. Dr Florence Tupin, Professor at Télécom Paris, has served on the Editorial Board of the Journal of Spatial Science for several years and has contributed her expertise to peer review of many submissions in her field. Dr Tupin’s dedication to quality and inciteful approach to peer review and manuscript development is greatly appreciated.
Impact factors for 2021 have also been released with the Journal of Spatial Science maintaining a steady impact factor of 1.840 accompanied by an improvement to Q3 in the Geography, physical category. Thank you for the support provided by our authors, subscribers and Editorial Board Members.
Papers published in this issue provide interesting insights into current research and practice in the spatial sciences.
Polyconic map projections are rarely used for world maps because traditional polyconic mappings do not have a favourable distortion pattern. This paper by Kerkovits demonstrates that the generalised versions of these projections can be adjusted well for global maps. The formulae are optimised numerically to ensure that the projections have as low distortion as possible. Furthermore, optimal polyconic mappings with further restrictions (e.g. rectangular graticules, equal-area) are also developed.
Jouybari, Bagherbandi and Nilfouroushan use three different procedures to analyse the effect of IMU and GNSS uncertainties on their final adjusted results. The outcome suggests that the method of block-wise GNSS shift correction is a better method for aerial triangulation. A comparison of checkpoint RMS residuals shows that the block-wise solution is on average 6 cm more accurate than the strip-wise solution.
Rosas and colleagues evaluated the use of low-cost materials for radiometric calibration of multispectral images. Four materials were tested: plywood panels painted with matte paint; plywood panels covered with synthetic nappa leather; ethylene vinyl acetate panels, and plywood panels covered with polyvinyl chloride canvas. The useful life of all materials and errors associated with their calibration were determined.
The standard algorithm for generating nearest-neighbour models determines the distance between every pair of nodes, resulting in quadratic running time. Such time complexity is common among spatial problems and impedes the generation of larger spatial models. In this article by Mocnik, an improved algorithm for the Mocnik model, an example of nearest-neighbour models, is introduced. Instead of solving k nearest-neighbour problems for each node, the improved algorithm exploits the notion of locality by introducing a corresponding spatial index, resulting in a linear average-case time complexity.
Remote sensing of soil moisture has low spatial resolution, and to validate soil moisture maps, point measurements gathered from scattered in situ stations are typically used. Sanchez, Almendra, Plaza, González-Zamora and Martínez-Fernández tested eight upscaling methods for in situ soil moisture based on geostatistical interpolations and physical characteristics, and were used to validate Soil Moisture and Ocean Salinity mission observations. Comparisons showed that the simple mean performs well and is similar to the proposed upscaling methods while overcoming the need for ancillary data.
GDOP minimisation criterion is applied to optimise the positioning configuration. In their study, Wang and colleagues introduced two kinds of GDOPs. The first kind of GDOP does not consider clock error, while the second kind does consider it. Cone configuration with lowest GDOP is discussed and extended for ultra-wideband positioning. For three-dimensional scenarios, the configuration sets with lowest GDOP can be obtained based on the first kind of GDOP. Furthermore, the constraint statistics are considered to optimise the global GDOP distribution in the positioning, and the study shows that the cone configuration with constraints is effective to optimise the deployment of anchors.
The study by Mora, Langford, Mislang, Josenhans and Chen examines and characterises the performance of RTK and RTN solutions at three test sites in Los Angeles County, California. The solutions were characterised to examine the dispersion of vertical measurements in the context of different environments. The results suggest that both methods have advantages and drawbacks; in particular, the data showed that the distribution and density of network stations, cellular network coverage and environmental dynamics have significant impacts on RTN vertical precision, where the vertical precision for the RTN measurements is observed to be 2–4 times lower in comparison to the RTK measurements.
The contribution by Nobakht-Ersi and Safari aims to show that careful ionospheric modelling can enhance the single-frequency code single point positioning (SPP) performance for both kinematic and static scenarios. Attention is restricted to the SPP quality driven by the IRIM under geomagnetic storm conditions. A Kalman filter-based model is formed for kinematic/static SPP users that combines GPS single-frequency code observations with the ionospheric corrections.
To compare and evaluate the performance of different multi-GNSS fractional cycle bias (FCBs) products and precise point positioning (PPP) ambiguity resolution, Lin, Qiao, Xiao and Du compare the stability and positioning performance of the School of Geodesy and Geomatics and CNES GPS/Galileo FCBs products. The results show that similar stability and high consistency are observed between the two products, and the difference in PPP ambiguity resolution bias between them is at the level of millimetres, and it is found that the epoch-interval of narrow-lane FCBs can be enlarged from 15 min to 30–180 min, to ease the transmission pressure on the communication link.
The phase difference method can compensate for atmospheric disturbance in GB-SAR interferometry without the process of phase unwrapping, but its accuracy and effectiveness have not been analysed. Liu and colleagues analyse and validate this method using a simulation experiment and two real data experiments. Furthermore, they establish a quadratic model of the phase difference method to deal with the large range observation.