Changing coordinates using appropriate mathematical models from one reference system to another may be influenced if the operation requires the change of datum. A set of transformation parameters has been adopted for ...Changing coordinates using appropriate mathematical models from one reference system to another may be influenced if the operation requires the change of datum. A set of transformation parameters has been adopted for Nigeria. However, the critical concern usually associated with the problem of transformation of coordinates is the issue of recoverability of the original values of transformed coordinates. The recursive effect of variables associated with spatial problems can be aptly modelled with an appropriate algorithm that set out a process to achieve a definite output. Consequently, the main thrust of this paper is to highlight the critical elements of the mathematical algorithm associated with the National Transformation Version 2 (NTv2) model adapted for the Nigerian Datum Transformation process. The adapted NTv2 model adopts the bi-linear interpolation approach and the covariance function obtained were used to generate transformation elements in latitude (Δ<em>φp</em>) and longitude (Δ<em>λp</em>) and corresponding accuracies at the lattice nodes. The mathematical algorithm of this adapted NTv2 model underscores the likely attainment of better and significant values and statistical indicator of the improved accuracy as the average shift values for latitude and longitude for any transformed points in Nigeria. This capability makes the mathematical algorithm to be adaptable and fit for the purpose of the transformation process. The improvement in the positional accuracy is directly attributable to the application of the NTv2 model which provides a flexible and robust system of modelling any inherent systematic error in the national network.展开更多
The Earth’s magnetic declination,a key parameter of the geomagnetic field,has long provided a fundamental reference for navigation,orientation,and geospatial positioning.Owing to temporal and spatial variations in th...The Earth’s magnetic declination,a key parameter of the geomagnetic field,has long provided a fundamental reference for navigation,orientation,and geospatial positioning.Owing to temporal and spatial variations in the geomagnetic field,periodic model updates are essential for maintaining positional accuracy and geophysical consistency.This study modelled the spatiotemporal variability of magnetic declination across Nigeria over 15 years(2010-2025)to enhance geomagnetic referencing for sustainable navigation and mapping systems.The study employed a quantitative geoscientific methodology.The study integrated International Geomagnetic Reference Field(IGRF-14)Gauss coefficients using MATLAB programming to compute magnetic field elements and generate declination models at a 1:50,000 scale.Analytical outputs revealed significant regional variations,with the North-West,South-South,and South-East zones recording the highest declination changes of 2.40˚,2.10˚,and 2.00˚,respectively.Conversely,the North-Central,North-East,and South-West zones exhibited relatively lower variations of 0.70˚,1.20˚,and 1.70˚,respectively.A comparative assessment between declination values from the developed model and those derived from the global geomagnetic calculator revealed minimal discrepancies(−0.009480 to−0.001340),with root mean square errors ranging from 0.00470 to 0.00670.These findings underscore the importance of the magnitude of secular variations of magnetic declination across Nigeria.The variability of these values provides a veritable basis to support geospatial infrastructure development,accurate navigation,and calibration of inertial systems.Regular updates of isogonic maps and geomagnetic parameters are therefore recommended to strengthen national geospatial frameworks,enhance disaster preparedness,and promote SDG-aligned geoscience innovations that underpin resilient infrastructure and sustainable urban development.展开更多
文摘Changing coordinates using appropriate mathematical models from one reference system to another may be influenced if the operation requires the change of datum. A set of transformation parameters has been adopted for Nigeria. However, the critical concern usually associated with the problem of transformation of coordinates is the issue of recoverability of the original values of transformed coordinates. The recursive effect of variables associated with spatial problems can be aptly modelled with an appropriate algorithm that set out a process to achieve a definite output. Consequently, the main thrust of this paper is to highlight the critical elements of the mathematical algorithm associated with the National Transformation Version 2 (NTv2) model adapted for the Nigerian Datum Transformation process. The adapted NTv2 model adopts the bi-linear interpolation approach and the covariance function obtained were used to generate transformation elements in latitude (Δ<em>φp</em>) and longitude (Δ<em>λp</em>) and corresponding accuracies at the lattice nodes. The mathematical algorithm of this adapted NTv2 model underscores the likely attainment of better and significant values and statistical indicator of the improved accuracy as the average shift values for latitude and longitude for any transformed points in Nigeria. This capability makes the mathematical algorithm to be adaptable and fit for the purpose of the transformation process. The improvement in the positional accuracy is directly attributable to the application of the NTv2 model which provides a flexible and robust system of modelling any inherent systematic error in the national network.
文摘The Earth’s magnetic declination,a key parameter of the geomagnetic field,has long provided a fundamental reference for navigation,orientation,and geospatial positioning.Owing to temporal and spatial variations in the geomagnetic field,periodic model updates are essential for maintaining positional accuracy and geophysical consistency.This study modelled the spatiotemporal variability of magnetic declination across Nigeria over 15 years(2010-2025)to enhance geomagnetic referencing for sustainable navigation and mapping systems.The study employed a quantitative geoscientific methodology.The study integrated International Geomagnetic Reference Field(IGRF-14)Gauss coefficients using MATLAB programming to compute magnetic field elements and generate declination models at a 1:50,000 scale.Analytical outputs revealed significant regional variations,with the North-West,South-South,and South-East zones recording the highest declination changes of 2.40˚,2.10˚,and 2.00˚,respectively.Conversely,the North-Central,North-East,and South-West zones exhibited relatively lower variations of 0.70˚,1.20˚,and 1.70˚,respectively.A comparative assessment between declination values from the developed model and those derived from the global geomagnetic calculator revealed minimal discrepancies(−0.009480 to−0.001340),with root mean square errors ranging from 0.00470 to 0.00670.These findings underscore the importance of the magnitude of secular variations of magnetic declination across Nigeria.The variability of these values provides a veritable basis to support geospatial infrastructure development,accurate navigation,and calibration of inertial systems.Regular updates of isogonic maps and geomagnetic parameters are therefore recommended to strengthen national geospatial frameworks,enhance disaster preparedness,and promote SDG-aligned geoscience innovations that underpin resilient infrastructure and sustainable urban development.
