bundle block adjustment with 3d natural cubic splines

bundle block adjustment with 3d natural cubic splines bundle block adjustment with 3d natural cubic splines

13.07.2015 Views

unknowns. The redundancy is 2nm-m-12 for one spline segment so that if two images(m=2) are used for bundle block adjustment, the redundancy is 4n-14. Four points arerequired to determine spline and spline location parameters in case one spline segmentand one degree of freedom to the overall redundancy budget is solved by each pointmeasurement with the extended collinearity equation. Arc-length parameterizationalso contributes one degree of freedom to the overall redundancy budget. The fifthpoint does not provide additional information to reduce the overall deficiency butonly makes spline parameters robust, which means it increases the overall precisionof the estimated parameters.This fact is an advantage of adopting splines which the number of degrees offreedom is four since in tie straight lines; only two points per line are independent.Independent information, the number of degrees of freedom, of a straight line is twofrom two points or a point with its tangent direction. A redundancy is r=2m-4 witha line expression of four parameters since equations are 2nm collinearity equationsand unknowns are 4+nm [59]. Only two points (n=2) are available to determine fourline parameters with two images (m=2) so at least three images must contain a tieline. The information content of t tie lines on m images is t(2m-4). One straight lineincreases two degrees of freedom to the redundancy budget and at least three linesare required in the space resection. An additional point on a straight line does notprovide additional information to reduce the rank deficiency of the recovery of EOPsbut only contributes image line coefficients. If spline location parameters or splineparameters enter the integrated adjustment model through stochastic constraints,employing extended collinearity equations is enough for solving the system withoutthe arc-length parameterization.74

The redundancy budget of a tie point is r=2m-3 so tie points provide one more independentequation than tie lines. However, using tie points requires semi-automaticmatching procedure to identify tie points on all images and employing linear featuresis more robust and accurate than point features for object recognition, posedetermination, and other higher photogrammetric activities.5.1 Synthetic data descriptionThe standard block configuration is generated by strips of images with approximately60% overlap in the flight direction and 20%-30% overlap in the neighboredflight strips. In bundle block adjustment, a ground feature is required at least intwo images to determine three dimensional coordinates. The simulation of aerial imageblock with six images, a forward overlap of 60% and a side overlap of 20%, isperformed to verify the feasibility of the proposed model in bundle block adjustmentwith synthetic data. EOPs of the simulation data set with six images are described intable 5.3 and figure 5.2 with 0.15m focal length and zero offsets from a fiducial-basedorigin to a perspective center origin of a camera. This means that interior orientationparameters are known and fixed. EOPs of six images are generated under theassumption of the vertical viewing condition.To evaluate the new bundle block adjustment model using natural cubic splines,the analysis of sensitivity and robustness of the model is required. Verification of themodel suitability can be assessed by the estimated parameters with the dispersionmatrix including standard deviations and correlations. The accuracy of bundle blockadjustment is determined by the geometry of a block of all images and the quality ofthe position and attitude information of a camera. For novel approaches, a simulation75

The redundancy budget of a tie point is r=2m-3 so tie points provide one more independentequation than tie lines. However, using tie points requires semi-automaticmatching procedure to identify tie points on all images and employing linear featuresis more robust and accurate than point features for object recognition, posedetermination, and other higher photogrammetric activities.5.1 Synthetic data descriptionThe standard <strong>block</strong> configuration is generated by strips of images <strong>with</strong> approximately60% overlap in the flight direction and 20%-30% overlap in the neighboredflight strips. In <strong>bundle</strong> <strong>block</strong> <strong>adjustment</strong>, a ground feature is required at least intwo images to determine three dimensional coordinates. The simulation of aerial image<strong>block</strong> <strong>with</strong> six images, a forward overlap of 60% and a side overlap of 20%, isperformed to verify the feasibility of the proposed model in <strong>bundle</strong> <strong>block</strong> <strong>adjustment</strong><strong>with</strong> synthetic data. EOPs of the simulation data set <strong>with</strong> six images are described intable 5.3 and figure 5.2 <strong>with</strong> 0.15m focal length and zero offsets from a fiducial-basedorigin to a perspective center origin of a camera. This means that interior orientationparameters are known and fixed. EOPs of six images are generated under theassumption of the vertical viewing condition.To evaluate the new <strong>bundle</strong> <strong>block</strong> <strong>adjustment</strong> model using <strong>natural</strong> <strong>cubic</strong> <strong>splines</strong>,the analysis of sensitivity and robustness of the model is required. Verification of themodel suitability can be assessed by the estimated parameters <strong>with</strong> the dispersionmatrix including standard deviations and correlations. The accuracy of <strong>bundle</strong> <strong>block</strong><strong>adjustment</strong> is determined by the geometry of a <strong>block</strong> of all images and the quality ofthe position and attitude information of a camera. For novel approaches, a simulation75

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