GNSS(global navigation satellite system)observations produce the geodetic position including latitude,longitude,and altitude(or ellipsoidal height)concerning the global reference datum WGS84(Word Geodetic System 1984)...GNSS(global navigation satellite system)observations produce the geodetic position including latitude,longitude,and altitude(or ellipsoidal height)concerning the global reference datum WGS84(Word Geodetic System 1984),which usually should be converted to another local datum to get the desired position meaning in a physical sense,coordinates of points in the local datum are usually calculated by the seven-parameter transformation method.This paper aims to validate the methods of position transformation between WGS84 and the Iraqi local datum Karbala 1979 using the UTM(universal transverse Mercator)projected coordinates directly.The proposed algorithm was tested for 10 ground control points in Erbil city and many selected points in other different cities over all Iraqi territory.The control points are measured by the CHCNAV i73 GNSS receiver.For the evaluation procedure,the RMSE(root mean square error)of the transformed coordinates is calculated with an average value of±10.715 m as an estimated uncertainty of the direct UTM coordinates transformation method over Erbil city territory,and more than±12 m over different places over Iraqi territory.展开更多
For a long time,the observations’adjustment concepts are doing based on the principle of Least Squares(LS),which so far,is the most popular technique that is widely used for such purposes.In the current study,the aut...For a long time,the observations’adjustment concepts are doing based on the principle of Least Squares(LS),which so far,is the most popular technique that is widely used for such purposes.In the current study,the author introduces a new vision of the measurements’adjustment that depends on the principle of the artificial neural network backpropagation(ANNB).However,the novel approach of the adjustment in the current study is based upon the principle of the measurement’s precision,which will be represented through the value of the variance(σ^(2)).Thus,the determination of the required residuals for the adjustment procedure can be derived from the variances of observations and the value of geometrical closure error.The evaluation of the proposed method of adjustment ANNB is done according to the parametric method of LS adjustment for two selected cases of observations,representing the equal and non-equal precision observations.The obtained results of adjustment using the new technique(ANNB)are fully agreed with the results of LS for the two evaluation cases.These results indicate good compatibility between the ANNB and the LS as two approaches for observations’adjustment.展开更多
The global navigation satellite systems(GNSS)provide an accurate three-dimensional positioning including the geodetic(ellipsoidal)height(h),which is,in most cases,must be transformed to the local/regional orthometric ...The global navigation satellite systems(GNSS)provide an accurate three-dimensional positioning including the geodetic(ellipsoidal)height(h),which is,in most cases,must be transformed to the local/regional orthometric height(H)to have physically the desired meaning of the elevation above the national vertical datum(e.g.,MSL(Mean Sea Level)).Usually,the local orthometric heights are determined based on the value of geoid undulation(N),which is obtained by methods of gravimetrical observations or derived by methods of interpolation utilizing the local geoid models(LGM).The current paper highlights one of the methods of generating LGM that is based on the geometrical relationship between the global datum WGS84 and the Iraqi datum Karbala 1979.The DGPS(Differential GPS)method is used to get the geodetic coordinates of about 97 selected points to cover the experimental area,within the boundaries of Erbil municipality,which has been partitioned into four parts.Therefore,four LGM were generated individually for each one of the four parts with an estimated uncertainty equal to±0.076 m.展开更多
文摘GNSS(global navigation satellite system)observations produce the geodetic position including latitude,longitude,and altitude(or ellipsoidal height)concerning the global reference datum WGS84(Word Geodetic System 1984),which usually should be converted to another local datum to get the desired position meaning in a physical sense,coordinates of points in the local datum are usually calculated by the seven-parameter transformation method.This paper aims to validate the methods of position transformation between WGS84 and the Iraqi local datum Karbala 1979 using the UTM(universal transverse Mercator)projected coordinates directly.The proposed algorithm was tested for 10 ground control points in Erbil city and many selected points in other different cities over all Iraqi territory.The control points are measured by the CHCNAV i73 GNSS receiver.For the evaluation procedure,the RMSE(root mean square error)of the transformed coordinates is calculated with an average value of±10.715 m as an estimated uncertainty of the direct UTM coordinates transformation method over Erbil city territory,and more than±12 m over different places over Iraqi territory.
文摘For a long time,the observations’adjustment concepts are doing based on the principle of Least Squares(LS),which so far,is the most popular technique that is widely used for such purposes.In the current study,the author introduces a new vision of the measurements’adjustment that depends on the principle of the artificial neural network backpropagation(ANNB).However,the novel approach of the adjustment in the current study is based upon the principle of the measurement’s precision,which will be represented through the value of the variance(σ^(2)).Thus,the determination of the required residuals for the adjustment procedure can be derived from the variances of observations and the value of geometrical closure error.The evaluation of the proposed method of adjustment ANNB is done according to the parametric method of LS adjustment for two selected cases of observations,representing the equal and non-equal precision observations.The obtained results of adjustment using the new technique(ANNB)are fully agreed with the results of LS for the two evaluation cases.These results indicate good compatibility between the ANNB and the LS as two approaches for observations’adjustment.
文摘The global navigation satellite systems(GNSS)provide an accurate three-dimensional positioning including the geodetic(ellipsoidal)height(h),which is,in most cases,must be transformed to the local/regional orthometric height(H)to have physically the desired meaning of the elevation above the national vertical datum(e.g.,MSL(Mean Sea Level)).Usually,the local orthometric heights are determined based on the value of geoid undulation(N),which is obtained by methods of gravimetrical observations or derived by methods of interpolation utilizing the local geoid models(LGM).The current paper highlights one of the methods of generating LGM that is based on the geometrical relationship between the global datum WGS84 and the Iraqi datum Karbala 1979.The DGPS(Differential GPS)method is used to get the geodetic coordinates of about 97 selected points to cover the experimental area,within the boundaries of Erbil municipality,which has been partitioned into four parts.Therefore,four LGM were generated individually for each one of the four parts with an estimated uncertainty equal to±0.076 m.
