matthew ono | Nnamdi Azikiwe University, Awka-Nigeria (original) (raw)

Papers by matthew ono

Throughout Nigeria, the structure and facilities needed for the operation of a Global Navigation ... more Throughout Nigeria, the structure and facilities needed for the operation of a Global Navigation Satellite System (GNSS) based Continuously Operating Reference Stations (CORS) has been set up at different locations in the country generally known as NIGerian Reference GNSS NETwork (NIGNET) for surveying and mapping. Different researchers have conducted investigations into the effect of the troposphere over the NIGNET. This study aims at comparing analytically the effect of five different a priori tropospheric models on GNSS signals in Southern Nigeria with a view to obtaining the best-fit model. The objectives include evaluation of the global tropospheric models in the baseline and position domain; and determining the best model for southern Nigeria. Observational data used were obtained from Office of Surveyor General of Nigerian Mapping Agency (OSGoF). GPS data were obtained from October 2010, to April 2011. Six processing strategies were employed these include; application of no m...

International Journal of Scientific Research in Science and Technology, Jun 12, 2021

A Control survey is a survey operation that is carried out in order to establish position of poin... more A Control survey is a survey operation that is carried out in order to establish position of points with a high degree of accuracy in order to support activities like mapping and map revisions, property boundary surveys, construction projects and so on. Control densification is a continuous exercise in the field of geomatics. This forms the basis upon which other geomatics and engineering activities geared toward development are referenced. This study is aimed at determining the coordinates of existing control points network along Ayetoro / Egbeda Atuba road using dual frequency GPS and Total Station with a view to comparing the accuracies of DGPS and Total Station using statistical analysis to determine which one has better accuracy. The Objectives of the study are to locate the existing control points, to collect the information/coordinates of the existing control points, and to carry out the observation using DGPS and Total station and process/compute the final coordinates and compare the results by using statistical analysis. The methodology that are adopted for this project is Satellite Positioning Technology using Differential Global Positioning System (DGPS) and Total Station. And the acquired data was processed and adjusted. The statistical analysis was used to compare the result obtained from DGPS and Total Station with the data collected from the Ministry of Land and Housing. The result of the analysis shows that DGPS has better accuracy. It is recommended that whenever more suitable and accurate method of measurement is to be employed, the DGPS method should be selected as this study has demonstrated and compared the accuracy of the two methods and showed that the DGPS method is better.

Earthquakes and Tremors are Tectonic activities traced to Crustal Motions with roots in the Conti... more Earthquakes and Tremors are Tectonic activities traced to Crustal Motions with roots in the Continental Drift Theory. These activities occur mostly at Plate Boundaries and along or close to Fault Lines. Nigeria was erroneously considered aseismic in the past, but studies have shown that Nigeria was never aseismic as information on different Tremors and Earthquakes abound. The recent occurrences of Tremors in Abuja, the Nation's Capital, call for a serious attention towards the definition of the Nigerian Fault Lines. An attempt towards the determination of the Fault Lines is made, using the Non-Geodetic and Geodetic Methods. The Non-Geodetic Method Seeks to connect the Epicenters of different Earthquakes and Tremors on record, in order to present a possible set of Fault Lines.

FUDMA JOURNAL OF SCIENCES, 2022

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.

FUDMA JOURNAL OF SCIENCES, 2022

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 ...

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<br> 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 coordin...

According to [1], the deflection of the vertical () is the angle between the direction of the gr... more According to [1], the deflection of the vertical () is the angle between the direction of the gravity vector g or plumb line at a point, and the ellipsoidal normal through the same point for a particular ellipsoid. It is conventionally divided into two perpendicular components; a north-south meridional component (ξ) and an east-west prime vertical component () (see Fig.1). The direction of the plumb line and its vertical deflection provide valuable information on the structure of Earth's gravity field. For several decades, astrogeodetic observations were primary gravity field observables and used for astrogeodetic geoid determinations, [2]. It can also be predicted using gravimetric, GPS and levelling methods and the digital Zenith cameras, [3]. Astro-geodetic technique adopts astronomical coordinates (, ) and geodetic coordinates (, ) while gravimetric technique is based on Stokes formula, using abnormalities of the earth gravitational field as the input data. In addition to the two techniques mentioned above, global geopotential and local gravimetric models as well as combined techniques (GPS/Levelling, GPS/Gravimetric, etc.), are used to attain such figures. Global geoid models, such as EGM 96 are developed by using the gravitational information of the whole world. Geoid heights are calculated by using the potential harmonic coefficients of the global geoid models. On the other hand, local geoid models vary, depending on the geodetic data resources of the country being considered. For regions with no gravity information, the orthometric heights obtained via geometric levelling and the ellipsoidal height obtained via GPS are used in combination. The deflection of the vertical is an important parameter of the local gravity field and has applications in surveying activities such as in determination of directions (bearings), azimuths, zenith angles and slope distances onto the ellipsoid. A practical example is the determination of water flow which requires the geoid knowledge. The position of the geoid in relation to the reference ellipsoid can be determined not only through geoid height but also by deflection of the vertical at the point of observation. It is well known that physical development such as road construction, drains, dams, tunnels etc require a good knowledge of the geoid, [4]. Ugbowo is a developing area in Benin City which requires a good knowledge of the geoid to enable geometric heights to be converted to practical heights so as to determine suitable gradients/slopes to ensure direction of flow of water. Determining the deflection of the vertical components of the study area, will enable the local geoid model of the study area to be determined.

New technologies are emerging and abound everywhere. They have made surveying practice quite inte... more New technologies are emerging and abound everywhere. They have made surveying practice quite interesting and easier. But our rural areas where majority population is residing are still quite under surveyed in this era of new emerging technology. Hence, our rural cadastre and land management remains in comatose. Investigations have shown that practicing surveyors still use the analogue driven instruments for most if not all their survey works. They lacked the innovation and prerequisite knowledge of the new technologies. Hence, they exhibit a lot of lukewarm in training and re-training programmes in the new methodologies. Also, existing laws (legislations) are archaic as there are no provisions for implementation of the new technologies. Further, our rural areas lacked the necessary reference framework (controls) to ensure that surveys are carried out to produce cadastral plans (to show size/extent, shape, ownership, etc) of land parcels. Consequently, surveyors create disparate surv...

International Journal of Geoinformatics and Geological Science, 2021

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 positionaldata. Use of dual frequency Hi-Target V30 Pro geodetic receivers also enhancesthe reliability and quality of GPS measurementsthrough 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-testvalues 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 canbe used interchangeably to pr...

GeographyRN: Urban Geography (Topic), 2018

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...

Journal of Environment and Earth Science, 2021

Over the second half of the twentieth century, the world has experienced enormous health improvem... more Over the second half of the twentieth century, the world has experienced enormous health improvements from the use of various technologies in the diagnosis, treatment, monitoring and reporting various disease. However, developing countries have benefited unequally from health gains, with many, especially in Sub-Saharan Africa (SSA), continuing to experience high mortality. This study aims to carry out a spatial analysis of healthcare facilities in the Federal Capital Territory (FCT) Abuja, Nigeria with a view of identifying the pattern of distribution of healthcare facilities. This aim was achieved by identifying and mapping the various health facilities in the FCT. The directory of Hospitals was collected from the Hospital Management Board of the FCT and the geographic location were collected using a handheld GPS device. The administrative map of Abuja and the Area Councils were digitized to obtain shapefiles for various classes of roads, railway lines, waterways and boundaries of the area councils. A geospatial database was created in the ArcMap 10.7 environment using the data collected. The locations of all healthcare facilities were plotted, and the spatial spread of healthcare facilities were analyses and queried. The healthcare facilities distribution shows a clustered pattern but underserving the study area with an average nearest neighbour ratio (NNR) for healthcare facilities in the study of 0.34 (p < 0.001) and the Z-score was −40.9 (p < 0.001), the low Z-score value indicate there is a less than 1% likelihood that this clustered pattern could be the result of deliberate planning. The healthcare facilities distribution pattern suggests a disorderly and inefficient distribution of healthcare facilities. Owing to the significance of the underserving of the urban area councils by healthcare facilities, policymakers may consider placing additional healthcare facilities to reduce the stress on the available healthcare facilities and personnel.

International Journal of Engineering Research and Advanced Technology, 2018

Ellipsoidal heights from GNSS require geoid model for conversion to orthometric height. The geoid... more Ellipsoidal heights from GNSS require geoid model for conversion to orthometric height. The geoid model could be global, regional or local. The lack of national geoid model in Nigeria makes development of local geoid very critical to local applications in place of integrated global geoid models. This study compares two polynomial geoid models for terrain representation in the FCT, Abuja. Nine coefficients were used to model the FCT surface for geoid interpolation and orthometric height modeling. Model A involved the use of the 2-D (x, y) positions while model B used 3-D (x, y,) where = (-) the difference in average ellipsoidal height () and each point's ellipsoidal height (). The term is based on the assumption that the geoid varies with topography and may hence possibly lead to some improvements in accuracy of orthometric height determination. DGPS observations were carried out to determine ellipsoid heights. Least squares adjustment was performed to compute the coefficients of the models. Model A achieved standard deviation of σ = 11 cm while Model B achieved σ = 13cm. Though, Model B has a term that included highly accurate ellipsoidal height differences (), it has not resulted into any accuracy improvement over the model A. Model A based on 2-D positions is hence the better of the two models. The t-test and hypothesis test at 95% confidence limit, however, showed that the two models did not differ significantly. Model A having lower standard deviation is recommended with GNSS determined ellipsoidal heights to determine orthometric heights within the FCT. This becomes an easy alternative to conventional spirit leveling technique for production of topographical maps, cadastral surveys, and engineering/environmental applications.

Journal of Environment and Earth Science, 2018

An important component in position determination of any point is its height. Orthometric height d... more An important component in position determination of any point is its height. Orthometric height determination has a significant role in geodesy, and it has wide-ranging application in numerous fields and activities. Orthometric height is the height above or below the geoid along the gravity plumb line. Orthometric height system is preferred to ellipsoidal height by many because of its relationship with the mean sea level (MSL). Determination of orthometric heights for Akure environs was carried out using gravimetric approach by determining geoidal undulations via Stokes integral and ellipsoidal heights via GPS observations. A total of 59 stations within the study area were occupied for gravity observation using Lacoste and Romberg (G-512 series) and its complete accessories. South GNSS instrument was used in static mode for position and ellipsoidal height determination. In order to determine orthometric heights of the study area, the difference between the tailored geoid height (N Taylor) and the ellipsoidal heights (h GPS) were computed. The result shows that the determined orthometric heights have a standard deviation value as 10.6121m with a standard error as 1.38159m. The contour map and the 3D surface map of the computed orthometric heights were produced for the study area. The study recommends the use of gravimetric method in orthometric height determination when the tailored geoid height is computed.

Scientific Research Journal, 2019

The application of gravity anomalies for gravimetric geoid model determination has necessitated t... more The application of gravity anomalies for gravimetric geoid model determination has necessitated the computation of normal gravity on the WGS 84 ellipsoid using the International Gravity Formula. For local gravimetric geoid model determination, the gravity anomalies are computed on the local ellipsoid adopted for geodetic computation in the area/region of study. To determine precise local gravimetric geoid model in countries where Clarke 1880 ellipsoid is adopted for geodetic computation, the theoretical gravity must be computed on the adopted geodetic computation surface. As a result, this paper derives a local theoretical gravity model on the Clarke 1880 ellipsoid for practical local geoid model determination. The model was derived using the Clarke 1880 ellipsoid parameters, angular velocity, gravitational constant and the Somiglinana's closed formula for normal gravity. The derived model was presented in two forms, model A and model B. The two forms of the derived model were compared to determine their suitability as well as agreement. The comparison results show that the two forms of the model agree. Thus, any of the model forms can be applied for accurate normal gravity computation where Clarke 1880 ellipsoid is adopted as a computation surface.

International Journal of Scientific Research in Science and Technology, 2019

Oyo state like most of the other states in the Nigeria has an old and conventional Geodetic Netwo... more Oyo state like most of the other states in the Nigeria has an old and conventional Geodetic Network. This network was established and computed using the conventional method of position determination and the science of navigation in the 1930- 1950's which is based on the 30th arc-meridian of the Clarke 1880 modified ellipsoid with its origin at L40 Minna datum. This does not satisfy the overgrowing mapping requirements of the state and as well as other Geo-related information requirements. The required data were acquired with GNSS receivers set up on each of the existing points in static mode. The reference network that was re- established consists of eight (8) primary points, covering an area of approximately ?12km?^2 with an average separation of about 7Km. The new network monuments are made of reinforced concrete, solidly cemented in the ground with metal caps (brass markers), and coordinated using the static carrier phase differential GPS measurement. Several observation sess...

International Journal of Advances in Scientific Research and Engineering, 2018

Monitoring the integrity of engineering structures such as bridges and tall buildings using geode... more Monitoring the integrity of engineering structures such as bridges and tall buildings using geodetic methods cannot be underestimated as they provide information about the health of the structures and their safety aspects as well the safety of the public. This study monitored and analyzed the vertical deformation of Palm House in Benin City using Digital Level. Four reference stations and six monitoring points were used. The digital level was used to determine the orthometric heights of the monitoring points with respect to the reference stations heights. The observations were carried out at six epochs of three months interval and adjusted using least squares adjustment technique to determine the reliability of the adjusted observations and that of the adjusted heights. The vertical displacement magnitudes of the monitoring points were computed using the heights differences between the first and the subsequent epochs observations. The evaluated displacement magnitudes were compared with their corresponding computed 95% confidence intervals to determine the significance of the reported movements. The comparison results showed that the building did not undergo any vertical displacement during the monitoring period. It was recommended that large engineering structures such as high rise buildings, bridges, etc should be monitored at regular basis so as to determine their structural integrity since any vertical displacement of the structure which can cause the structure to collapse and thereby result to loss of lives and properties can be detected by epoch monitoring and appropriate measures can be taken.

International Journal of Scientific and Research Publications (IJSRP), 2018

Consistency is an important characteristic in height systems which the mean sea level (msl) surfa... more Consistency is an important characteristic in height systems which the mean sea level (msl) surface cannot guarantee. Only a geoid surface can provide height consistency. The quality of geoid undulation (N) will obviously affect the resulting orthometric height (H) determined from GNSS. The geoid undulation may be global, regional/national and local. Online software CSRS-PPP was used for post processing rinex data. 2008 was computed from AllTrans EGM2008 geoid calculator while h was used to compute from the relationship N= h-H. H is the existing orthometric height. Twenty-four controls with FCT 260 P as base reference station were used for this study. The computed standard deviation of differences in − 2008 (σ) is used as accuracy indicator and σ =0.419m .The root mean square error (RMSE) is 0.934m. This indicates the quality and reliability of the geoid undulation from the EGM2008 model. Comparing the observed and 2008 , the use of global models may not satisfy the accuracy level of orthometric height desired for local applications in the FCT, Abuja. GNSS (GPS) may be used along with local geoid model as a way to acquire acceptable orthometric height. The smaller the-2008 makes it better model. The range of 1.585m from (-2008) in this study is a strong indication that global models should be avoided as much as possible in local applications.

SUMMARY A coordinate system forms a common frame of reference for the description of positions an... more SUMMARY A coordinate system forms a common frame of reference for the description of positions and on the other hand, coordinates are simply an ordered set of numbers that are used to describe the positions or features in a coordinate system (Featherstone and Vanicek, 1999). Transformation parameters are required to move from one system to another. In Nigeria, we have different coordinate systems based on different origins which are used for various mapping purposes. Also, new technologies like global positioning system have provided new methods of coordinates' determination. The map production, update and revision are based on geographical coordinates; map-grid coordinates or coordinates in an arbitrary system. Some others are based on old (local) system. There are no truly accepted transformation parameters. The consequences are obvious confusion and misrepresentation of features. In fact surveyors and survey practitioners are already using the new technology based on geocent...

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.

Throughout Nigeria, the structure and facilities needed for the operation of a Global Navigation ... more Throughout Nigeria, the structure and facilities needed for the operation of a Global Navigation Satellite System (GNSS) based Continuously Operating Reference Stations (CORS) has been set up at different locations in the country generally known as NIGerian Reference GNSS NETwork (NIGNET) for surveying and mapping. Different researchers have conducted investigations into the effect of the troposphere over the NIGNET. This study aims at comparing analytically the effect of five different a priori tropospheric models on GNSS signals in Southern Nigeria with a view to obtaining the best-fit model. The objectives include evaluation of the global tropospheric models in the baseline and position domain; and determining the best model for southern Nigeria. Observational data used were obtained from Office of Surveyor General of Nigerian Mapping Agency (OSGoF). GPS data were obtained from October 2010, to April 2011. Six processing strategies were employed these include; application of no m...

International Journal of Scientific Research in Science and Technology, Jun 12, 2021

A Control survey is a survey operation that is carried out in order to establish position of poin... more A Control survey is a survey operation that is carried out in order to establish position of points with a high degree of accuracy in order to support activities like mapping and map revisions, property boundary surveys, construction projects and so on. Control densification is a continuous exercise in the field of geomatics. This forms the basis upon which other geomatics and engineering activities geared toward development are referenced. This study is aimed at determining the coordinates of existing control points network along Ayetoro / Egbeda Atuba road using dual frequency GPS and Total Station with a view to comparing the accuracies of DGPS and Total Station using statistical analysis to determine which one has better accuracy. The Objectives of the study are to locate the existing control points, to collect the information/coordinates of the existing control points, and to carry out the observation using DGPS and Total station and process/compute the final coordinates and compare the results by using statistical analysis. The methodology that are adopted for this project is Satellite Positioning Technology using Differential Global Positioning System (DGPS) and Total Station. And the acquired data was processed and adjusted. The statistical analysis was used to compare the result obtained from DGPS and Total Station with the data collected from the Ministry of Land and Housing. The result of the analysis shows that DGPS has better accuracy. It is recommended that whenever more suitable and accurate method of measurement is to be employed, the DGPS method should be selected as this study has demonstrated and compared the accuracy of the two methods and showed that the DGPS method is better.

Earthquakes and Tremors are Tectonic activities traced to Crustal Motions with roots in the Conti... more Earthquakes and Tremors are Tectonic activities traced to Crustal Motions with roots in the Continental Drift Theory. These activities occur mostly at Plate Boundaries and along or close to Fault Lines. Nigeria was erroneously considered aseismic in the past, but studies have shown that Nigeria was never aseismic as information on different Tremors and Earthquakes abound. The recent occurrences of Tremors in Abuja, the Nation's Capital, call for a serious attention towards the definition of the Nigerian Fault Lines. An attempt towards the determination of the Fault Lines is made, using the Non-Geodetic and Geodetic Methods. The Non-Geodetic Method Seeks to connect the Epicenters of different Earthquakes and Tremors on record, in order to present a possible set of Fault Lines.

FUDMA JOURNAL OF SCIENCES, 2022

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.

FUDMA JOURNAL OF SCIENCES, 2022

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 ...

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<br> 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 coordin...

According to [1], the deflection of the vertical () is the angle between the direction of the gr... more According to [1], the deflection of the vertical () is the angle between the direction of the gravity vector g or plumb line at a point, and the ellipsoidal normal through the same point for a particular ellipsoid. It is conventionally divided into two perpendicular components; a north-south meridional component (ξ) and an east-west prime vertical component () (see Fig.1). The direction of the plumb line and its vertical deflection provide valuable information on the structure of Earth's gravity field. For several decades, astrogeodetic observations were primary gravity field observables and used for astrogeodetic geoid determinations, [2]. It can also be predicted using gravimetric, GPS and levelling methods and the digital Zenith cameras, [3]. Astro-geodetic technique adopts astronomical coordinates (, ) and geodetic coordinates (, ) while gravimetric technique is based on Stokes formula, using abnormalities of the earth gravitational field as the input data. In addition to the two techniques mentioned above, global geopotential and local gravimetric models as well as combined techniques (GPS/Levelling, GPS/Gravimetric, etc.), are used to attain such figures. Global geoid models, such as EGM 96 are developed by using the gravitational information of the whole world. Geoid heights are calculated by using the potential harmonic coefficients of the global geoid models. On the other hand, local geoid models vary, depending on the geodetic data resources of the country being considered. For regions with no gravity information, the orthometric heights obtained via geometric levelling and the ellipsoidal height obtained via GPS are used in combination. The deflection of the vertical is an important parameter of the local gravity field and has applications in surveying activities such as in determination of directions (bearings), azimuths, zenith angles and slope distances onto the ellipsoid. A practical example is the determination of water flow which requires the geoid knowledge. The position of the geoid in relation to the reference ellipsoid can be determined not only through geoid height but also by deflection of the vertical at the point of observation. It is well known that physical development such as road construction, drains, dams, tunnels etc require a good knowledge of the geoid, [4]. Ugbowo is a developing area in Benin City which requires a good knowledge of the geoid to enable geometric heights to be converted to practical heights so as to determine suitable gradients/slopes to ensure direction of flow of water. Determining the deflection of the vertical components of the study area, will enable the local geoid model of the study area to be determined.

New technologies are emerging and abound everywhere. They have made surveying practice quite inte... more New technologies are emerging and abound everywhere. They have made surveying practice quite interesting and easier. But our rural areas where majority population is residing are still quite under surveyed in this era of new emerging technology. Hence, our rural cadastre and land management remains in comatose. Investigations have shown that practicing surveyors still use the analogue driven instruments for most if not all their survey works. They lacked the innovation and prerequisite knowledge of the new technologies. Hence, they exhibit a lot of lukewarm in training and re-training programmes in the new methodologies. Also, existing laws (legislations) are archaic as there are no provisions for implementation of the new technologies. Further, our rural areas lacked the necessary reference framework (controls) to ensure that surveys are carried out to produce cadastral plans (to show size/extent, shape, ownership, etc) of land parcels. Consequently, surveyors create disparate surv...

International Journal of Geoinformatics and Geological Science, 2021

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 positionaldata. Use of dual frequency Hi-Target V30 Pro geodetic receivers also enhancesthe reliability and quality of GPS measurementsthrough 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-testvalues 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 canbe used interchangeably to pr...

GeographyRN: Urban Geography (Topic), 2018

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...

Journal of Environment and Earth Science, 2021

Over the second half of the twentieth century, the world has experienced enormous health improvem... more Over the second half of the twentieth century, the world has experienced enormous health improvements from the use of various technologies in the diagnosis, treatment, monitoring and reporting various disease. However, developing countries have benefited unequally from health gains, with many, especially in Sub-Saharan Africa (SSA), continuing to experience high mortality. This study aims to carry out a spatial analysis of healthcare facilities in the Federal Capital Territory (FCT) Abuja, Nigeria with a view of identifying the pattern of distribution of healthcare facilities. This aim was achieved by identifying and mapping the various health facilities in the FCT. The directory of Hospitals was collected from the Hospital Management Board of the FCT and the geographic location were collected using a handheld GPS device. The administrative map of Abuja and the Area Councils were digitized to obtain shapefiles for various classes of roads, railway lines, waterways and boundaries of the area councils. A geospatial database was created in the ArcMap 10.7 environment using the data collected. The locations of all healthcare facilities were plotted, and the spatial spread of healthcare facilities were analyses and queried. The healthcare facilities distribution shows a clustered pattern but underserving the study area with an average nearest neighbour ratio (NNR) for healthcare facilities in the study of 0.34 (p < 0.001) and the Z-score was −40.9 (p < 0.001), the low Z-score value indicate there is a less than 1% likelihood that this clustered pattern could be the result of deliberate planning. The healthcare facilities distribution pattern suggests a disorderly and inefficient distribution of healthcare facilities. Owing to the significance of the underserving of the urban area councils by healthcare facilities, policymakers may consider placing additional healthcare facilities to reduce the stress on the available healthcare facilities and personnel.

International Journal of Engineering Research and Advanced Technology, 2018

Ellipsoidal heights from GNSS require geoid model for conversion to orthometric height. The geoid... more Ellipsoidal heights from GNSS require geoid model for conversion to orthometric height. The geoid model could be global, regional or local. The lack of national geoid model in Nigeria makes development of local geoid very critical to local applications in place of integrated global geoid models. This study compares two polynomial geoid models for terrain representation in the FCT, Abuja. Nine coefficients were used to model the FCT surface for geoid interpolation and orthometric height modeling. Model A involved the use of the 2-D (x, y) positions while model B used 3-D (x, y,) where = (-) the difference in average ellipsoidal height () and each point's ellipsoidal height (). The term is based on the assumption that the geoid varies with topography and may hence possibly lead to some improvements in accuracy of orthometric height determination. DGPS observations were carried out to determine ellipsoid heights. Least squares adjustment was performed to compute the coefficients of the models. Model A achieved standard deviation of σ = 11 cm while Model B achieved σ = 13cm. Though, Model B has a term that included highly accurate ellipsoidal height differences (), it has not resulted into any accuracy improvement over the model A. Model A based on 2-D positions is hence the better of the two models. The t-test and hypothesis test at 95% confidence limit, however, showed that the two models did not differ significantly. Model A having lower standard deviation is recommended with GNSS determined ellipsoidal heights to determine orthometric heights within the FCT. This becomes an easy alternative to conventional spirit leveling technique for production of topographical maps, cadastral surveys, and engineering/environmental applications.

Journal of Environment and Earth Science, 2018

An important component in position determination of any point is its height. Orthometric height d... more An important component in position determination of any point is its height. Orthometric height determination has a significant role in geodesy, and it has wide-ranging application in numerous fields and activities. Orthometric height is the height above or below the geoid along the gravity plumb line. Orthometric height system is preferred to ellipsoidal height by many because of its relationship with the mean sea level (MSL). Determination of orthometric heights for Akure environs was carried out using gravimetric approach by determining geoidal undulations via Stokes integral and ellipsoidal heights via GPS observations. A total of 59 stations within the study area were occupied for gravity observation using Lacoste and Romberg (G-512 series) and its complete accessories. South GNSS instrument was used in static mode for position and ellipsoidal height determination. In order to determine orthometric heights of the study area, the difference between the tailored geoid height (N Taylor) and the ellipsoidal heights (h GPS) were computed. The result shows that the determined orthometric heights have a standard deviation value as 10.6121m with a standard error as 1.38159m. The contour map and the 3D surface map of the computed orthometric heights were produced for the study area. The study recommends the use of gravimetric method in orthometric height determination when the tailored geoid height is computed.

Scientific Research Journal, 2019

The application of gravity anomalies for gravimetric geoid model determination has necessitated t... more The application of gravity anomalies for gravimetric geoid model determination has necessitated the computation of normal gravity on the WGS 84 ellipsoid using the International Gravity Formula. For local gravimetric geoid model determination, the gravity anomalies are computed on the local ellipsoid adopted for geodetic computation in the area/region of study. To determine precise local gravimetric geoid model in countries where Clarke 1880 ellipsoid is adopted for geodetic computation, the theoretical gravity must be computed on the adopted geodetic computation surface. As a result, this paper derives a local theoretical gravity model on the Clarke 1880 ellipsoid for practical local geoid model determination. The model was derived using the Clarke 1880 ellipsoid parameters, angular velocity, gravitational constant and the Somiglinana's closed formula for normal gravity. The derived model was presented in two forms, model A and model B. The two forms of the derived model were compared to determine their suitability as well as agreement. The comparison results show that the two forms of the model agree. Thus, any of the model forms can be applied for accurate normal gravity computation where Clarke 1880 ellipsoid is adopted as a computation surface.

International Journal of Scientific Research in Science and Technology, 2019

Oyo state like most of the other states in the Nigeria has an old and conventional Geodetic Netwo... more Oyo state like most of the other states in the Nigeria has an old and conventional Geodetic Network. This network was established and computed using the conventional method of position determination and the science of navigation in the 1930- 1950's which is based on the 30th arc-meridian of the Clarke 1880 modified ellipsoid with its origin at L40 Minna datum. This does not satisfy the overgrowing mapping requirements of the state and as well as other Geo-related information requirements. The required data were acquired with GNSS receivers set up on each of the existing points in static mode. The reference network that was re- established consists of eight (8) primary points, covering an area of approximately ?12km?^2 with an average separation of about 7Km. The new network monuments are made of reinforced concrete, solidly cemented in the ground with metal caps (brass markers), and coordinated using the static carrier phase differential GPS measurement. Several observation sess...

International Journal of Advances in Scientific Research and Engineering, 2018

Monitoring the integrity of engineering structures such as bridges and tall buildings using geode... more Monitoring the integrity of engineering structures such as bridges and tall buildings using geodetic methods cannot be underestimated as they provide information about the health of the structures and their safety aspects as well the safety of the public. This study monitored and analyzed the vertical deformation of Palm House in Benin City using Digital Level. Four reference stations and six monitoring points were used. The digital level was used to determine the orthometric heights of the monitoring points with respect to the reference stations heights. The observations were carried out at six epochs of three months interval and adjusted using least squares adjustment technique to determine the reliability of the adjusted observations and that of the adjusted heights. The vertical displacement magnitudes of the monitoring points were computed using the heights differences between the first and the subsequent epochs observations. The evaluated displacement magnitudes were compared with their corresponding computed 95% confidence intervals to determine the significance of the reported movements. The comparison results showed that the building did not undergo any vertical displacement during the monitoring period. It was recommended that large engineering structures such as high rise buildings, bridges, etc should be monitored at regular basis so as to determine their structural integrity since any vertical displacement of the structure which can cause the structure to collapse and thereby result to loss of lives and properties can be detected by epoch monitoring and appropriate measures can be taken.

International Journal of Scientific and Research Publications (IJSRP), 2018

Consistency is an important characteristic in height systems which the mean sea level (msl) surfa... more Consistency is an important characteristic in height systems which the mean sea level (msl) surface cannot guarantee. Only a geoid surface can provide height consistency. The quality of geoid undulation (N) will obviously affect the resulting orthometric height (H) determined from GNSS. The geoid undulation may be global, regional/national and local. Online software CSRS-PPP was used for post processing rinex data. 2008 was computed from AllTrans EGM2008 geoid calculator while h was used to compute from the relationship N= h-H. H is the existing orthometric height. Twenty-four controls with FCT 260 P as base reference station were used for this study. The computed standard deviation of differences in − 2008 (σ) is used as accuracy indicator and σ =0.419m .The root mean square error (RMSE) is 0.934m. This indicates the quality and reliability of the geoid undulation from the EGM2008 model. Comparing the observed and 2008 , the use of global models may not satisfy the accuracy level of orthometric height desired for local applications in the FCT, Abuja. GNSS (GPS) may be used along with local geoid model as a way to acquire acceptable orthometric height. The smaller the-2008 makes it better model. The range of 1.585m from (-2008) in this study is a strong indication that global models should be avoided as much as possible in local applications.

SUMMARY A coordinate system forms a common frame of reference for the description of positions an... more SUMMARY A coordinate system forms a common frame of reference for the description of positions and on the other hand, coordinates are simply an ordered set of numbers that are used to describe the positions or features in a coordinate system (Featherstone and Vanicek, 1999). Transformation parameters are required to move from one system to another. In Nigeria, we have different coordinate systems based on different origins which are used for various mapping purposes. Also, new technologies like global positioning system have provided new methods of coordinates' determination. The map production, update and revision are based on geographical coordinates; map-grid coordinates or coordinates in an arbitrary system. Some others are based on old (local) system. There are no truly accepted transformation parameters. The consequences are obvious confusion and misrepresentation of features. In fact surveyors and survey practitioners are already using the new technology based on geocent...

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.