Three-Dimensional Reconstruction and Visualization of Underwater Bridge Piers Using Sonar Imaging.

The quality of underwater bridge piers significantly impacts bridge safety and long-term usability. To address limitations in conventional inspection methods, this paper presents a sonar-based technique for the three-dimensional (3D) reconstruction and visualization of underwater bridge piers. Advanced MS1000 scanning sonar is employed to detect and image bridge piers. Automated image preprocessing, including filtering, denoising, binarization, filling, and morphological operations, introduces an enhanced wavelet denoising method to accurately extract the foundation contour coordinates of bridge piers from sonar images. Using these coordinates, along with undamaged pier dimensions and sonar distances, a model-driven approach for a 3D pier reconstruction algorithm is developed. This algorithm leverages multiple sonar data points to reconstruct damaged piers through multiplication. The Visualization Toolkit (VTK) and surface contour methodology are utilized for 3D visualization, enabling interactive manipulation for enhanced observation and analysis. Experimental results indicate a relative error of 13.56% for the hole volume and 10.65% for the spalling volume, demonstrating accurate replication of bridge pier defect volumes by the reconstructed models. Experimental validation confirms the method's accuracy and effectiveness in reconstructing underwater bridge piers in three dimensions, providing robust support for safety assessments and contributing significantly to bridge stability and long-term safety assurance.

[Evaluation of postural characteristics in patients with vertigo by modified clinical test of sensory interaction and balance].

OBJECTIVE: To investigate the application of modified clinical test of sensory interaction and balance (mCTSIB) in the patients with vertigo. METHOD: One hundred and six patients with vertigo (62 cases with peripheral and 44 cases with central vestibular disorder) were taken the mCTSIB of the firm surface and foam surface with eye open and eye closed for 30 seconds respectively. The standing foam surface was to interrupt the somatosensory and closing eyes was to interrupt the visual input in the postural stability. The falling during the test was recorded. The results between the mCTSIB and video nystagmography (VNG) were compared. RESULT: In vestibular peripheral disorder, the abnormal of mCTSIB was 45.16% (28/62) and agreement to VNG was 67.74% (42/62). In vestibular central disorder, the abnormal of mCTSIB was 27.27% (12/44) and agreement to VNG was 81.82% (36/44). For all these patients with vertigo in this study, the abnormal of mCTSIB was 37.74% (40/106) and agreement to VNG was 73.58% (78/106). Regarding the falling as abnormality, the mCTSIB was not significant different between the vestibular peripheral and central disorders (chi2 = 3.505, P > 0.05). CONCLUSION: Although the mCTSIB, which was easy to carry out, can not be a method to differentiate the vestibular peripheral and central disorders, it was a suitable to assess the ability of sensory interaction to maintain balance in patients with vertigo.

[Postural stability after head-shaking in the healthy young individuals].

OBJECTIVE: To investigate the postural stability after head-shaking in the normal young individuals. METHOD: Twenty-eight normal young individuals were taken the static posturography under 4 standing conditions including (T1) head center and eye open (EO), (T2) head center and eye closed, (T3) after head-shaking and EO, (T4) after head-shaking and EC. The sway velocity (SV) of center of pressure under feet in each testing condition was recorded as parameter and each test protocol was 30 s. RESULT: All examinee did not fall in each testing condition. (1) The SV increased (4.60 +/- 6.36) % after head-shaking in the EO condition, while the (8.86 +/- 8.27) % was demonstrated in the EC condition. There was significant difference between these two degrees of increase (t = 2.759, P < 0.01). (2) In static head orientation, the SV of EC (T2) increased (9.83 +/- 5.10)% compared with the SV of EO condition (T1). However, the SV of EC (T4) increased (14.05 +/- 6.89) % compared with the SV of EO condition (T3) after head-shaking. And there was significant difference between these two degrees of increase (t = 2.772, P < 0.01). CONCLUSION: The stimuli of head-shaking that interrupted input from vestibular end organ can affect the function of vestibulospinal reflex in healthy young individual, especially when the visual input was interrupted simultaneously. In order to keeping balance after head-shaking, there was a complex mechanism sensory reorganization even in the normal young subject.

[Timed balance test and static posturography in the patients with unilateral vestibular hypofunction].

OBJECTIVE: To investigate the balance function of the patients with unilateral vestibular hypofunction (UVH) by timed balance tests and static posturography (SPG). METHODS: Sixty-five subjects with UVH and 92 healthy subjects were taken the timed balance tests under differential stance including (1) standard Romberg test, (2) feet apart stance test, (3) tandem and (4) unilateral standing tests with eyes open and eyes closed. The average timing that subjects kept balance before falling in each standing conditions was recorded by stopwatch as the timed result. The body sway velocity during the test (1) and (2) were also recorded by the SPG. RESULTS: The timed results of the tandem and unilateral standing with eyes open and eyes closed in the UVH group were decreased (P < 0.001) compared with the control group. The body sway velocity of the standard Romberg test and foot apart stance with eyes open was not different between the UVH group and control group (P-value was 0.118 and 0.110 for the two tests respectively), and the difference was significant in the eyes closed condition (P < 0.001). For the two groups, the body sway velocity of foot apart standing was decreased than that of the standard Romberg test with eyes open and eyes closed (P < 0.05 or P < 0.001). Significant correlations were not found between the timed results and sway velocity results in both two groups respectively (P > 0.05). CONCLUSIONS: According to clinical assessment of balance function in UVH, the tandem and unilateral stance test could provide the additional information about the upright stance to the SPG measurement. The effect of foot position on the results of SPG should been considered in clinic.