A Surveyor Registered by Surveyors Council of Nigeria (SURCON) with Ph.D in Surveying and Geoinformatics (Geodesy and Geodynamics Option). Phone: 08064382127 Address: BENIN CITY, NIGERIA
Satellite altimetry has revolutionized our ability to measure Earth's surface with unprecedented ... more Satellite altimetry has revolutionized our ability to measure Earth's surface with unprecedented accuracy, offering invaluable insights into various geophysical phenomena. This study presents the determination of geoid heights (Ns) of Awka and Environ utilizing the Broadview RADAR Altimeter Toolbox (BRAT) in conjunction with data from the Sentinel-3 missions. The geoid, a surface of constant gravitational potential representing mean sea level, is a fundamental reference surface for geodetic measurements and understanding Earth's gravity field. The methodology involves processing raw altimetry data acquired by the Sentinel-3 missions using BRAT, followed by precise corrections for various factors affecting the altimeter measurements, such as atmospheric delays, sea state bias, and orbit errors. Subsequently, the derived SSH data are combined with precise geoid models to compute the geoid heights at different spatial resolutions. The results demonstrate the effectiveness of the approach in determining geoid height (N) with high precision and spatial resolution, offering valuable contributions to geodetic research and applications. The utilization of Sentinel-3 data combined with BRAT facilitates robust and accurate geoid determination, which is essential for a wide range of geospatial applications, including oceanography, geophysics, and climate studies. The integration of BRAT and Sentinel-3 missions offers a powerful tool for geodetic research and applications, contributing to our understanding of Earth's dynamic processes and improving the accuracy of geospatial measurements.
Journal of Geography, Environment and Earth Science International, 2024
Anambra State is facing a number of environmental challenges that require geodetic infrastructure... more Anambra State is facing a number of environmental challenges that require geodetic infrastructure for effective solutions. Unfortunately, much remains to be done in this area as many control stations have been removed from their original locations, leaving some of their pillars in disrepair. To address this issue, a study was conducted to assess the reliability of the geodetic control network in Anambra for various applications. The study involved identifying the location of control stations within the state, assessing the status of the geodetic control network, and confirming the status of individual control stations. Using a handheld GNSS receiver, the control stations were located and critically assessed for their physical condition. In addition, in situ checks were carried out to determine if they were still maintaining their original positions. The results of the study showed that 36% of the visited and located control stations are still intact in their original positions, while 56% have been removed and 8% require maintenance. There should be continuous sensitization of the public on the importance of geodetic controls and the dangers of their destruction.
The proposed transformation of the global geoid model method for the determination of the local g... more The proposed transformation of the global geoid model method for the determination of the local geoid model of Nigeria has only been applied in part of the Federal Capital Territory, Abuja. To determine the consistency of the accuracy of the method for the intended purpose, there is a need to apply it in some other parts of the country. As a result, this study presents the verification of the consistency of the proposed transformation of global geoid method accuracy for local geoid model of Nigeria determination. DGNSS observations were carried out to obtain the coordinates of the used points. The processed global geographic coordinates were used with online software (GeoidEval) to obtain the EGM 08 geoid heights of the points. The global geographic coordinates, the global geoid heights of the points and the transformation parameters from WGS 84 to Minna datum were applied to obtain the transformed (local) geoid heights of the points using a Microsoft Excel program. The transformed geoid heights were compared with their corresponding geoid heights from the gravimetric-geometric local geoid model of the study area to obtain the model RMSE (accuracy). The obtained accuracy (2.0172 m) was compared with those of the gravimetric-geometric geoid model of the study area (0.675 m) and the transformation of global geoid heights when the method was applied in part of Abuja (0.0014 m). The comparison results showed the inconsistency of the accuracy of the proposed method. It is recommended that the method should not be applied for the intended purpose.
The application of the transformation geoid model in Benin City has necessitated its fitting to t... more The application of the transformation geoid model in Benin City has necessitated its fitting to the existing gravimetric-geometric geoid model of the study area. The transformation geoid model was determined using the Kotsakis (2008) model for the transformation of global geoid heights to local geoidal undulations. To obtain its accuracy, the root mean square error (RMSE) index was applied. The computed accuracy is 2.0172 m. To apply the determined geoid model in the study area, as well as improving on the computed accuracy, the model was fitted to the gravimetric-geometric geoid model of the study area. The fitting result shows that geoid heights can be computed using the determined geoid model with an accuracy of 1.1041 m in the study area.
GeologyRN: Remote Sensing Methods in Geology (Topic), 2018
The direct determination of NTM and UTM plane rectangular coordinates from post processing of sta... more The direct determination of NTM and UTM plane rectangular coordinates from post processing of static DGPS/GNSS observations on the Nigeria Minna datum using post processing software is feasible if the rectangular NTM or UTM coordinates of the control/base station are known, and the belt or zone in which the observations were acquired is accurately identified and the identified belt or zone parameters correctly applied during data processing. But most users of these post processing software process these observations in NTM rectangular coordinates and subsequently convert the NTM grid coordinates to UTM grid positions which are not always correct. Consequently, this paper presents detailed procedures and feasibility of obtaining directly NTM or UTM coordinates from post processing of DGPS observations on the Nigeria Minna datum using the appropriate belt or zone parameters and post processing software that accompanied the DGPS/GNSS receivers. The procedures and feasibility of obtaini...
The deflection of the vertical is an important parameter of the local gravity field which must no... more The deflection of the vertical is an important parameter of the local gravity field which must not be neglected during survey measurements. In most survey (Geodetic) measurements, the components of deflection of the vertical are not considered as a result of non availability of detailed maps in such area or region. The components of deflection of the vertical using the GPS/levelling (Geometric) method were determined. Fifteen ancillary stations and one control station were used. The orthometric and the ellipsoidal heights of the stations were determined using digital Level and GPS respectively. The least squares adjustment principle was carried out on the observations with the components as parameters. The values obtained are: -0.550” ± 0.000001” and - 0.395” ± 0.0000006” for ξ (north-south) and ƞ(east-west) directions respectively. The components of deflection of the vertical of the study area were also computed using three geopotential models (EGM08, EGM96 and EGM84). They are: ξ ...
The displacements of engineering structures have been investigated by different researchers using... more The displacements of engineering structures have been investigated by different researchers using one of the various geodetic methods such as GPS, Total Station, Levelling, InSAR, Photogrammetry, Theodolite, EDM and 3D Laser but in that, the accuracy of these methods have not really been compared to determine which of the methods is better in terms of accuracy, magnitude and direction of the expected deformation. This study monitored and modelled the deformation of Palm House in Benin City using GPS and Total Station and compared the accuracy of the two horizontal methods. Four reference stations and two sets of monitoring points were used. The DGPS observations were used to determine the roof monitoring points rectangular coordinates while the total station was used to determine the 10th floor base monitoring points rectangular coordinates and their bearings and distances from the reference stations. The observations were carried out at six epochs of three months interval and adjus...
Journal of Geography, Environment and Earth Science International, 2021
The non-availability of ellipsoidal heights of local geodetic Datums has made it necessary for th... more The non-availability of ellipsoidal heights of local geodetic Datums has made it necessary for the application of ellipsoidal heights transformation models to the available global ellipsoidal heights to obtain their respective theoretical heights in local Datums. It is required to know the accuracy, as well as reliability of any model of interest before its application. For that reason, this study comparatively analyses the Molodensky and Kotsakis models for the transformation of ellipsoidal heights between geocentric and non-geocentric Datums to determine the reliability of the Kotsakis model. The Global Navigation Satellite System (GNSS) data of the used stations were processed in World Geodetic System 1984 (WGS84) datum to obtain their global geographic coordinates and ellipsoidal heights. The coordinates, ellipsoidal heights and the transformation parameters between WGS84 and Minna Datums were applied to the Molodensky and Kotsakis models to compute the Clarke 1880 theoretical heights of the stations. The Molodensky model was used as a reference to which the Kotsakis model ellipsoidal heights were compared to obtain the Kotsakis model ellipsoidal heights discrepancies, as well as residuals. The residuals were used to compute the 172 Root Mean Square Error (RMSE) of the Kotsakis model. The computed RMSE, as well as reliability of the model is 1.244 m. The study concluded that the low reliability, as well as accuracy of the Kotsakis model might be as a result of the two rotation datum shift parameters in it as they are the main differences between the two models.
For the reason that there are several factors that affect large engineering structures, monitorin... more For the reason that there are several factors that affect large engineering structures, monitoring them to determine their deformations for safety purpose cannot be underestimated. Therefore, this study presents monitoring and analysis of vertical and horizontal deformations of a large structure, Palm House Building, Benin City, to determine its structural integrity. Four reference stations, two sets of monitoring points and two conventional geodetic techniques, total station and digital level were used. The positions and heights of the reference stations were respectively determined using CHC900 dual frequency GNSS receivers and digital level with respect to nearby control station and benchmark. The two sets of monitoring points were observed at three epochs at interval of six months using total station and digital level with respect to the reference stations. The observations were adjusted with least squares technique to determine the reliability as well as the accuracy of the adj...
A local geoid model for Evboriaria, Benin City using the geometric (GPS/Levelling) method was det... more A local geoid model for Evboriaria, Benin City using the geometric (GPS/Levelling) method was determined for calculation of mean sea level heights. Fifty points were established for the model and ten points were used for interpolation. The geoid heights were determined by finding the difference between the observed orthometric heights and the ellipsoidal heights. The polynomial regression model D was used for the interpolation of the orthometric heights. The computed mean standard deviation between the observed orthometric heights and the interpolated orthometric heights was ± 21cm. A mean geoidal undulation of 28.410m was computed using the gravimetric method. The computed orthometric heights using the gravimetry mean geoidal undulation were compared with the observed orthometric heights and seen to be identical. It is recommended that orthometric heights of project areas should be determined from GPS observations with the local geoid model of the area also determined.
Safety is the primary and most important reason for monitoring the deformations of engineering st... more Safety is the primary and most important reason for monitoring the deformations of engineering structures. It could also help in improving our knowledge of the mechanical behaviour of engineering structures. Engineering structures are subject to deformation due to factors such as changes of ground water level, traffic load changes, tidal and tectonic phenomena. The Ikpoba River Bridge in Benin City whose traffic load has increased was monitored using GPS technology. The bridge was investigated as a result of carrying more load than usual due to the expansion of the road and dredging activities that had taken place in the river in 2008. One reference station and six monitoring points were involved in the monitoring of the bridge. The regularity of the survey was thirty days, and six observation epochs were used. Each monitoring point was occupied for about thirty minutes during the observation. The observation data were processed with compass software. The processed coordinates were ...
Differential GPS/GNSS positioning gives accurate coordinates as well as positions of observed poi... more Differential GPS/GNSS positioning gives accurate coordinates as well as positions of observed points on the earth surface. To obtain the accuracy as well as the reliability and the most probable positions of observed points using the post processing software that accompanies the receivers, least squares adjustment technique is applied. Applying least squares adjustment technique requires three or more receivers, that is two or more rovers and one base receiver to be used. Using three or more receivers makes the observation a closed loop observation. But in most cases where the number of points whose positions are to be determined is small, the observations are carried out with only two (rover and base) receivers. Using only two receivers (rover and base) implies that each of the points will be occupied one after the other with respect to the base receiver. In this, least squares adjustment cannot be applied as the observation is not a closed loop one, hence, the accuracy of the obse...
Global Positioning System (GPS) static measurements require post-processing to determine 3-D posi... more Global Positioning System (GPS) static measurements require post-processing to determine 3-D positions coordinates i.e. Eastings, Northings, and ellipsoidal height (E, N, h) of various points of interests. The adoption of differential GPS (DGPS) approach for data capture improves on the positional data. Use of dual frequency Hi-Target V30 Pro geodetic receivers also enhances the reliability and quality of GPS measurements through online processors. Online post-processing software (OPUS, CSRS-PPP, magicGNSS) were used to process the uploaded Receiver INdependent EXchange format (RINEX) data for the GPS position determination. ANOVA statistics was used to analyze the results. Computed F-test values compared against critical F-test table values and hypothesis testing was carried out. The results indicate that there is no significant difference between the three online post processing software. It is recommended that any of the online post-processing software can be used interchangeably...
Asian Journal of Advanced Research and Reports, 2021
The reconciliation of engineering designs that do not have survey information, that involve accur... more The reconciliation of engineering designs that do not have survey information, that involve accurate configuration of the proposed constructions at their respective locations on-site requires first a topographic survey to obtain the perimeter survey plan, which in turn, shows the area, shape, perimeter and orientation of the site; spot heights plan showing the existing ground levels thereby used to decide on suitable gradients and determine appropriate finished ground surface, coordinates of the turning points of outlines of the proposed constructions and their respective elevations. For that reason, this study determines the topography and drains the site for the Benin City Bus Rapid Transit (BRT) station in Oredo Local Government Area of Edo State. A topographic survey was carried out to produce topographic plans. The accuracy of the survey was computed to determine its reliability. The perimeter survey plan was plotted using AutoCAD Civil 3D Land Desktop Companion 2009 to present the area, shape, perimeter and orientation of the site. The TIN method was used for the computation of the volume of earthworks. The existing and the finished ground surfaces, vector, as well as the flow direction plans, contour plans and the 3D surface maps were plotted using Surfer 11 to show graphically the existing and the proposed topography of the site. A network of drainages was established to drain the site. The study has shown that the site can be drained in two ways, into the moat behind it and existing drainage along Obakhavbaye.
The importance of practical, as well as orthometric heights in engineering cannot be underestimat... more The importance of practical, as well as orthometric heights in engineering cannot be underestimated as it is required for the determination of proposed construction levels and to direct the flow of water. This study presents the determination of orthometric heights of points using gravimetric/GPS and geodetic levelling approaches and compares the resolution of the two approaches to determine which of the methods is better for orthometric height determination in the study area. A total of 59 stations were occupy for gravity observation using Lacoste and Romberg (G-512 series) gravimeter to obtain the absolute gravity values of the points. GNSS observation was carried out in static mode using South GNSS receivers to obtain the positions and ellipsoidal heights of the points. The modified Stokes’ integral was applied to obtain the geoid heights of the points. Similarly, levelling was carried out using the geodetic level to obtain the level heights of the points. The orthometric correction was applied to the geodetic levelling results to obtain precise level heights of the points. The RMSE index was applied to compute the accuracy of the geoid models. The computed result shows that orthometric heights can be obtained in the study area using the two models with an accuracy of 0.3536m. Z-test was carried out to determine if there is any significant difference between the two methods. The test results show that statistically, there is no significant difference between the two methods. Hence, the two methods can be applied for orthometric heights determination in the study area.
World Journal of Advanced Research and Reviews, 2020
The importance of the local geoid model for the computation of accurate geoid heights, as well as... more The importance of the local geoid model for the computation of accurate geoid heights, as well as orthometric heights used for engineering constructions, necessitated its establishment in areas, regions or countries. Consequently, this study establishes the local geometric geoid model of Busoga, Uganda, using the geometric method. A total of 26 points were used in the study, 20 points for the development of the model and 6 test points. GNSS observations were acquired with Trimble GNSS dual-frequency receivers and processed with Bernese (V5.2) and Spectra Precision Survey Office (v4.1) software to obtain the coordinates and ellipsoidal heights of the points. Differences between the existing orthometric and ellipsoidal heights were computed to obtain the geoid heights. The Least squares adjustment technique was applied to determine the fit, as well as the Bicubic and Multiquadratic models' parameters. The Root Mean Squares Error (RMSE) index was used to compute the accuracy of the models. The geoid models were compared with their RMSE, as well as accuracy to determine which of them is more suitable for application in the study area. The comparison result shows that the Multiquadratic geoid model is more suitable for implementation in the study area. A Microsoft Excel program was developed for the application of the model in the study area.
The improvement of the accuracy of a local geometric geoid model using the same data set (geoid h... more The improvement of the accuracy of a local geometric geoid model using the same data set (geoid heights) requires the fitting of a higher degree polynomial surface to the data set. Consequently, this paper presents improving the local geometric geoid model of FCT, Abuja accuracy by fitting a higher order polynomial surface. A fifth degree polynomial surface was fit to the existing geoid heights of 24 points used previously for the determination of the geometric geoid model of the study area to improve its accuracy. The least squares adjustment technique was applied to compute the model parameters, as well as the fit. The RMSE index was applied to compute the accuracy of the model. The computed accuracy (0.081m) of the model was compared with those of the previously determined geoid models (Multiquadratic, 0.110m and Bicubic, 0.136m models) of the study area to determine which of the models best fit the study area, as well as has the highest resolution. The comparison result shows that the fifth degree polynomial surface best fit the study area.
The conversion of theoretical, as well as geometric heights to practical heights requires the app... more The conversion of theoretical, as well as geometric heights to practical heights requires the application of geoidal undulations from a geoid model. The various global geopotential models that are readily available for application in any part of the world do not best-fit regions, as well as countries. As a result, there is a need to determine the local geoid models of local areas, regions and countries. This study determines the local geoid model of Kampala in Uganda for orthometric heights computation by comparing three plane geometric geoid surfaces. A total of 19 points were used in the study. The least squares adjustment technique was applied to compute the models' parameters. Microsoft Excel programs were developed for the application of the models in the study area. The Root Mean Square Index was applied to compute the accuracy of the models. The three geometric geoid models were compared using their accuracy to determine which of them is most suitable for application in the study area. The comparison results show that the three models can be applied in the study area with more reliability, with greater confidence in model 2.
International Journal of Scientific and Technological Research, 2020
The position occupied by the geoid in the computation of orthometric height (H) from GNSS observa... more The position occupied by the geoid in the computation of orthometric height (H) from GNSS observations is crucial and hence requires the geoid model parameters obtained with the application of least squares technique, be approximated to a reasonable number of significant figures in its (geoid) modelling to enable a high-resolution geometric geoid, be determined. As a result, this study presents the implication of significant number in geodetic computations using geometric geoid model of FCT, Abuja as a case study. The number of significant figures of the model parameters was varied, starting from 6 to 22 significant figures to enable the Root Mean Square Errors (RMSEs), as well as the accuracy of the model, be obtained at the varied numbers of significant figures. The obtained results show that the highest accuracy of the model is obtained if the model parameters are approximated to a reasonable number of significant figures.
Satellite altimetry has revolutionized our ability to measure Earth's surface with unprecedented ... more Satellite altimetry has revolutionized our ability to measure Earth's surface with unprecedented accuracy, offering invaluable insights into various geophysical phenomena. This study presents the determination of geoid heights (Ns) of Awka and Environ utilizing the Broadview RADAR Altimeter Toolbox (BRAT) in conjunction with data from the Sentinel-3 missions. The geoid, a surface of constant gravitational potential representing mean sea level, is a fundamental reference surface for geodetic measurements and understanding Earth's gravity field. The methodology involves processing raw altimetry data acquired by the Sentinel-3 missions using BRAT, followed by precise corrections for various factors affecting the altimeter measurements, such as atmospheric delays, sea state bias, and orbit errors. Subsequently, the derived SSH data are combined with precise geoid models to compute the geoid heights at different spatial resolutions. The results demonstrate the effectiveness of the approach in determining geoid height (N) with high precision and spatial resolution, offering valuable contributions to geodetic research and applications. The utilization of Sentinel-3 data combined with BRAT facilitates robust and accurate geoid determination, which is essential for a wide range of geospatial applications, including oceanography, geophysics, and climate studies. The integration of BRAT and Sentinel-3 missions offers a powerful tool for geodetic research and applications, contributing to our understanding of Earth's dynamic processes and improving the accuracy of geospatial measurements.
Journal of Geography, Environment and Earth Science International, 2024
Anambra State is facing a number of environmental challenges that require geodetic infrastructure... more Anambra State is facing a number of environmental challenges that require geodetic infrastructure for effective solutions. Unfortunately, much remains to be done in this area as many control stations have been removed from their original locations, leaving some of their pillars in disrepair. To address this issue, a study was conducted to assess the reliability of the geodetic control network in Anambra for various applications. The study involved identifying the location of control stations within the state, assessing the status of the geodetic control network, and confirming the status of individual control stations. Using a handheld GNSS receiver, the control stations were located and critically assessed for their physical condition. In addition, in situ checks were carried out to determine if they were still maintaining their original positions. The results of the study showed that 36% of the visited and located control stations are still intact in their original positions, while 56% have been removed and 8% require maintenance. There should be continuous sensitization of the public on the importance of geodetic controls and the dangers of their destruction.
The proposed transformation of the global geoid model method for the determination of the local g... more The proposed transformation of the global geoid model method for the determination of the local geoid model of Nigeria has only been applied in part of the Federal Capital Territory, Abuja. To determine the consistency of the accuracy of the method for the intended purpose, there is a need to apply it in some other parts of the country. As a result, this study presents the verification of the consistency of the proposed transformation of global geoid method accuracy for local geoid model of Nigeria determination. DGNSS observations were carried out to obtain the coordinates of the used points. The processed global geographic coordinates were used with online software (GeoidEval) to obtain the EGM 08 geoid heights of the points. The global geographic coordinates, the global geoid heights of the points and the transformation parameters from WGS 84 to Minna datum were applied to obtain the transformed (local) geoid heights of the points using a Microsoft Excel program. The transformed geoid heights were compared with their corresponding geoid heights from the gravimetric-geometric local geoid model of the study area to obtain the model RMSE (accuracy). The obtained accuracy (2.0172 m) was compared with those of the gravimetric-geometric geoid model of the study area (0.675 m) and the transformation of global geoid heights when the method was applied in part of Abuja (0.0014 m). The comparison results showed the inconsistency of the accuracy of the proposed method. It is recommended that the method should not be applied for the intended purpose.
The application of the transformation geoid model in Benin City has necessitated its fitting to t... more The application of the transformation geoid model in Benin City has necessitated its fitting to the existing gravimetric-geometric geoid model of the study area. The transformation geoid model was determined using the Kotsakis (2008) model for the transformation of global geoid heights to local geoidal undulations. To obtain its accuracy, the root mean square error (RMSE) index was applied. The computed accuracy is 2.0172 m. To apply the determined geoid model in the study area, as well as improving on the computed accuracy, the model was fitted to the gravimetric-geometric geoid model of the study area. The fitting result shows that geoid heights can be computed using the determined geoid model with an accuracy of 1.1041 m in the study area.
GeologyRN: Remote Sensing Methods in Geology (Topic), 2018
The direct determination of NTM and UTM plane rectangular coordinates from post processing of sta... more The direct determination of NTM and UTM plane rectangular coordinates from post processing of static DGPS/GNSS observations on the Nigeria Minna datum using post processing software is feasible if the rectangular NTM or UTM coordinates of the control/base station are known, and the belt or zone in which the observations were acquired is accurately identified and the identified belt or zone parameters correctly applied during data processing. But most users of these post processing software process these observations in NTM rectangular coordinates and subsequently convert the NTM grid coordinates to UTM grid positions which are not always correct. Consequently, this paper presents detailed procedures and feasibility of obtaining directly NTM or UTM coordinates from post processing of DGPS observations on the Nigeria Minna datum using the appropriate belt or zone parameters and post processing software that accompanied the DGPS/GNSS receivers. The procedures and feasibility of obtaini...
The deflection of the vertical is an important parameter of the local gravity field which must no... more The deflection of the vertical is an important parameter of the local gravity field which must not be neglected during survey measurements. In most survey (Geodetic) measurements, the components of deflection of the vertical are not considered as a result of non availability of detailed maps in such area or region. The components of deflection of the vertical using the GPS/levelling (Geometric) method were determined. Fifteen ancillary stations and one control station were used. The orthometric and the ellipsoidal heights of the stations were determined using digital Level and GPS respectively. The least squares adjustment principle was carried out on the observations with the components as parameters. The values obtained are: -0.550” ± 0.000001” and - 0.395” ± 0.0000006” for ξ (north-south) and ƞ(east-west) directions respectively. The components of deflection of the vertical of the study area were also computed using three geopotential models (EGM08, EGM96 and EGM84). They are: ξ ...
The displacements of engineering structures have been investigated by different researchers using... more The displacements of engineering structures have been investigated by different researchers using one of the various geodetic methods such as GPS, Total Station, Levelling, InSAR, Photogrammetry, Theodolite, EDM and 3D Laser but in that, the accuracy of these methods have not really been compared to determine which of the methods is better in terms of accuracy, magnitude and direction of the expected deformation. This study monitored and modelled the deformation of Palm House in Benin City using GPS and Total Station and compared the accuracy of the two horizontal methods. Four reference stations and two sets of monitoring points were used. The DGPS observations were used to determine the roof monitoring points rectangular coordinates while the total station was used to determine the 10th floor base monitoring points rectangular coordinates and their bearings and distances from the reference stations. The observations were carried out at six epochs of three months interval and adjus...
Journal of Geography, Environment and Earth Science International, 2021
The non-availability of ellipsoidal heights of local geodetic Datums has made it necessary for th... more The non-availability of ellipsoidal heights of local geodetic Datums has made it necessary for the application of ellipsoidal heights transformation models to the available global ellipsoidal heights to obtain their respective theoretical heights in local Datums. It is required to know the accuracy, as well as reliability of any model of interest before its application. For that reason, this study comparatively analyses the Molodensky and Kotsakis models for the transformation of ellipsoidal heights between geocentric and non-geocentric Datums to determine the reliability of the Kotsakis model. The Global Navigation Satellite System (GNSS) data of the used stations were processed in World Geodetic System 1984 (WGS84) datum to obtain their global geographic coordinates and ellipsoidal heights. The coordinates, ellipsoidal heights and the transformation parameters between WGS84 and Minna Datums were applied to the Molodensky and Kotsakis models to compute the Clarke 1880 theoretical heights of the stations. The Molodensky model was used as a reference to which the Kotsakis model ellipsoidal heights were compared to obtain the Kotsakis model ellipsoidal heights discrepancies, as well as residuals. The residuals were used to compute the 172 Root Mean Square Error (RMSE) of the Kotsakis model. The computed RMSE, as well as reliability of the model is 1.244 m. The study concluded that the low reliability, as well as accuracy of the Kotsakis model might be as a result of the two rotation datum shift parameters in it as they are the main differences between the two models.
For the reason that there are several factors that affect large engineering structures, monitorin... more For the reason that there are several factors that affect large engineering structures, monitoring them to determine their deformations for safety purpose cannot be underestimated. Therefore, this study presents monitoring and analysis of vertical and horizontal deformations of a large structure, Palm House Building, Benin City, to determine its structural integrity. Four reference stations, two sets of monitoring points and two conventional geodetic techniques, total station and digital level were used. The positions and heights of the reference stations were respectively determined using CHC900 dual frequency GNSS receivers and digital level with respect to nearby control station and benchmark. The two sets of monitoring points were observed at three epochs at interval of six months using total station and digital level with respect to the reference stations. The observations were adjusted with least squares technique to determine the reliability as well as the accuracy of the adj...
A local geoid model for Evboriaria, Benin City using the geometric (GPS/Levelling) method was det... more A local geoid model for Evboriaria, Benin City using the geometric (GPS/Levelling) method was determined for calculation of mean sea level heights. Fifty points were established for the model and ten points were used for interpolation. The geoid heights were determined by finding the difference between the observed orthometric heights and the ellipsoidal heights. The polynomial regression model D was used for the interpolation of the orthometric heights. The computed mean standard deviation between the observed orthometric heights and the interpolated orthometric heights was ± 21cm. A mean geoidal undulation of 28.410m was computed using the gravimetric method. The computed orthometric heights using the gravimetry mean geoidal undulation were compared with the observed orthometric heights and seen to be identical. It is recommended that orthometric heights of project areas should be determined from GPS observations with the local geoid model of the area also determined.
Safety is the primary and most important reason for monitoring the deformations of engineering st... more Safety is the primary and most important reason for monitoring the deformations of engineering structures. It could also help in improving our knowledge of the mechanical behaviour of engineering structures. Engineering structures are subject to deformation due to factors such as changes of ground water level, traffic load changes, tidal and tectonic phenomena. The Ikpoba River Bridge in Benin City whose traffic load has increased was monitored using GPS technology. The bridge was investigated as a result of carrying more load than usual due to the expansion of the road and dredging activities that had taken place in the river in 2008. One reference station and six monitoring points were involved in the monitoring of the bridge. The regularity of the survey was thirty days, and six observation epochs were used. Each monitoring point was occupied for about thirty minutes during the observation. The observation data were processed with compass software. The processed coordinates were ...
Differential GPS/GNSS positioning gives accurate coordinates as well as positions of observed poi... more Differential GPS/GNSS positioning gives accurate coordinates as well as positions of observed points on the earth surface. To obtain the accuracy as well as the reliability and the most probable positions of observed points using the post processing software that accompanies the receivers, least squares adjustment technique is applied. Applying least squares adjustment technique requires three or more receivers, that is two or more rovers and one base receiver to be used. Using three or more receivers makes the observation a closed loop observation. But in most cases where the number of points whose positions are to be determined is small, the observations are carried out with only two (rover and base) receivers. Using only two receivers (rover and base) implies that each of the points will be occupied one after the other with respect to the base receiver. In this, least squares adjustment cannot be applied as the observation is not a closed loop one, hence, the accuracy of the obse...
Global Positioning System (GPS) static measurements require post-processing to determine 3-D posi... more Global Positioning System (GPS) static measurements require post-processing to determine 3-D positions coordinates i.e. Eastings, Northings, and ellipsoidal height (E, N, h) of various points of interests. The adoption of differential GPS (DGPS) approach for data capture improves on the positional data. Use of dual frequency Hi-Target V30 Pro geodetic receivers also enhances the reliability and quality of GPS measurements through online processors. Online post-processing software (OPUS, CSRS-PPP, magicGNSS) were used to process the uploaded Receiver INdependent EXchange format (RINEX) data for the GPS position determination. ANOVA statistics was used to analyze the results. Computed F-test values compared against critical F-test table values and hypothesis testing was carried out. The results indicate that there is no significant difference between the three online post processing software. It is recommended that any of the online post-processing software can be used interchangeably...
Asian Journal of Advanced Research and Reports, 2021
The reconciliation of engineering designs that do not have survey information, that involve accur... more The reconciliation of engineering designs that do not have survey information, that involve accurate configuration of the proposed constructions at their respective locations on-site requires first a topographic survey to obtain the perimeter survey plan, which in turn, shows the area, shape, perimeter and orientation of the site; spot heights plan showing the existing ground levels thereby used to decide on suitable gradients and determine appropriate finished ground surface, coordinates of the turning points of outlines of the proposed constructions and their respective elevations. For that reason, this study determines the topography and drains the site for the Benin City Bus Rapid Transit (BRT) station in Oredo Local Government Area of Edo State. A topographic survey was carried out to produce topographic plans. The accuracy of the survey was computed to determine its reliability. The perimeter survey plan was plotted using AutoCAD Civil 3D Land Desktop Companion 2009 to present the area, shape, perimeter and orientation of the site. The TIN method was used for the computation of the volume of earthworks. The existing and the finished ground surfaces, vector, as well as the flow direction plans, contour plans and the 3D surface maps were plotted using Surfer 11 to show graphically the existing and the proposed topography of the site. A network of drainages was established to drain the site. The study has shown that the site can be drained in two ways, into the moat behind it and existing drainage along Obakhavbaye.
The importance of practical, as well as orthometric heights in engineering cannot be underestimat... more The importance of practical, as well as orthometric heights in engineering cannot be underestimated as it is required for the determination of proposed construction levels and to direct the flow of water. This study presents the determination of orthometric heights of points using gravimetric/GPS and geodetic levelling approaches and compares the resolution of the two approaches to determine which of the methods is better for orthometric height determination in the study area. A total of 59 stations were occupy for gravity observation using Lacoste and Romberg (G-512 series) gravimeter to obtain the absolute gravity values of the points. GNSS observation was carried out in static mode using South GNSS receivers to obtain the positions and ellipsoidal heights of the points. The modified Stokes’ integral was applied to obtain the geoid heights of the points. Similarly, levelling was carried out using the geodetic level to obtain the level heights of the points. The orthometric correction was applied to the geodetic levelling results to obtain precise level heights of the points. The RMSE index was applied to compute the accuracy of the geoid models. The computed result shows that orthometric heights can be obtained in the study area using the two models with an accuracy of 0.3536m. Z-test was carried out to determine if there is any significant difference between the two methods. The test results show that statistically, there is no significant difference between the two methods. Hence, the two methods can be applied for orthometric heights determination in the study area.
World Journal of Advanced Research and Reviews, 2020
The importance of the local geoid model for the computation of accurate geoid heights, as well as... more The importance of the local geoid model for the computation of accurate geoid heights, as well as orthometric heights used for engineering constructions, necessitated its establishment in areas, regions or countries. Consequently, this study establishes the local geometric geoid model of Busoga, Uganda, using the geometric method. A total of 26 points were used in the study, 20 points for the development of the model and 6 test points. GNSS observations were acquired with Trimble GNSS dual-frequency receivers and processed with Bernese (V5.2) and Spectra Precision Survey Office (v4.1) software to obtain the coordinates and ellipsoidal heights of the points. Differences between the existing orthometric and ellipsoidal heights were computed to obtain the geoid heights. The Least squares adjustment technique was applied to determine the fit, as well as the Bicubic and Multiquadratic models' parameters. The Root Mean Squares Error (RMSE) index was used to compute the accuracy of the models. The geoid models were compared with their RMSE, as well as accuracy to determine which of them is more suitable for application in the study area. The comparison result shows that the Multiquadratic geoid model is more suitable for implementation in the study area. A Microsoft Excel program was developed for the application of the model in the study area.
The improvement of the accuracy of a local geometric geoid model using the same data set (geoid h... more The improvement of the accuracy of a local geometric geoid model using the same data set (geoid heights) requires the fitting of a higher degree polynomial surface to the data set. Consequently, this paper presents improving the local geometric geoid model of FCT, Abuja accuracy by fitting a higher order polynomial surface. A fifth degree polynomial surface was fit to the existing geoid heights of 24 points used previously for the determination of the geometric geoid model of the study area to improve its accuracy. The least squares adjustment technique was applied to compute the model parameters, as well as the fit. The RMSE index was applied to compute the accuracy of the model. The computed accuracy (0.081m) of the model was compared with those of the previously determined geoid models (Multiquadratic, 0.110m and Bicubic, 0.136m models) of the study area to determine which of the models best fit the study area, as well as has the highest resolution. The comparison result shows that the fifth degree polynomial surface best fit the study area.
The conversion of theoretical, as well as geometric heights to practical heights requires the app... more The conversion of theoretical, as well as geometric heights to practical heights requires the application of geoidal undulations from a geoid model. The various global geopotential models that are readily available for application in any part of the world do not best-fit regions, as well as countries. As a result, there is a need to determine the local geoid models of local areas, regions and countries. This study determines the local geoid model of Kampala in Uganda for orthometric heights computation by comparing three plane geometric geoid surfaces. A total of 19 points were used in the study. The least squares adjustment technique was applied to compute the models' parameters. Microsoft Excel programs were developed for the application of the models in the study area. The Root Mean Square Index was applied to compute the accuracy of the models. The three geometric geoid models were compared using their accuracy to determine which of them is most suitable for application in the study area. The comparison results show that the three models can be applied in the study area with more reliability, with greater confidence in model 2.
International Journal of Scientific and Technological Research, 2020
The position occupied by the geoid in the computation of orthometric height (H) from GNSS observa... more The position occupied by the geoid in the computation of orthometric height (H) from GNSS observations is crucial and hence requires the geoid model parameters obtained with the application of least squares technique, be approximated to a reasonable number of significant figures in its (geoid) modelling to enable a high-resolution geometric geoid, be determined. As a result, this study presents the implication of significant number in geodetic computations using geometric geoid model of FCT, Abuja as a case study. The number of significant figures of the model parameters was varied, starting from 6 to 22 significant figures to enable the Root Mean Square Errors (RMSEs), as well as the accuracy of the model, be obtained at the varied numbers of significant figures. The obtained results show that the highest accuracy of the model is obtained if the model parameters are approximated to a reasonable number of significant figures.
NIGERIA ASSOCIATION OF GEODESY (NAG) 2024 Scientific Conference and General Assembly, 2024
It is well-known that positions are processed on the local ellipsoids adopted for geodetic comput... more It is well-known that positions are processed on the local ellipsoids adopted for geodetic computation in a country. In Nigeria, some of the geographic coordinates of the control stations were determined on the WGS 84 ellipsoid. The connection of new works to these control stations requires their transformation to the local ellipsoid, Clarke 1880 coordinates using suitable datum transformation software to make them fit into existing local geodetic networks. Consequently, this paper has comparatively analyzed the accuracy of some geodetic datum transformation software to determine the most suitable one for transformation between WGS 84 and Minna Datums. The positions of five points were obtained from the processing of GNSS observations using Compass post-processing software. The WGS 84 geographic coordinates of the points were transformed and converted to rectangular coordinates in the Minna datum using Columbus, AllTrans and GeoCalc software. The transformed and converted coordinates of the points were compared with the rectangular coordinates of the points obtained with Compass software to determine the most suitable software for application between WGS 84 and Minna Datums. The comparison results show that Columbus and AllTrans software are more appropriate for the exercise.
NIGERIA ASSOCIATION OF GEODESY (NAG) 2024 Scientific Conference and General Assembly, 2024
To ensure accurate positioning of points acquired through DGPS/GNSS observations on the WGS84 ell... more To ensure accurate positioning of points acquired through DGPS/GNSS observations on the WGS84 ellipsoid in each country, transformation parameters must be applied. This is because positions are determined with respect to the local datum/ellipsoid used for geodetic computation in each country. Prior to the publication of new/unified transformation parameters by the Office of the Surveyor-General of the Federation (OSGOF), multinational oil companies in Nigeria used various sets of transformation parameters. As a result, it's necessary to verify which positions computed with the old sets of transformation parameters agree with those computed using the new/unified ones. This study compares positions computed from DGPS/GNSS observations using both old and new transformation parameters. Four different points were observed and processed using Compass post-processing software, and the resulting coordinates were compared. The comparison showed that the positions computed using three different sets of transformation parameters (SPDC, AGIP, and DMA) agree with those computed using the unified ones. It is recommended that the datum shift parameters previously determined and used by the SPDC, AGIP, and DMA are accurate and can be used for position calculation in Nigeria.
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Papers by ETEJE SYLVESTER OKIEMUTE