The Experts below are selected from a list of 6507 Experts worldwide ranked by ideXlab platform
Jose M Sasian - One of the best experts on this subject based on the ideXlab platform.
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adaptive dispersion formula for index interpolation and chromatic aberration correction
Optics Express, 2014Co-Authors: Jose M SasianAbstract:This paper defines and discusses a glass dispersion formula that is adaptive. The formula exhibits superior convergence with a minimum number of coefficients. Using this formula we rationalize the correction of chromatic aberration per spectrum order. We compare the formula with the Sellmeier and Buchdahl formulas for glasses in the Schott catalogue. The six coefficient adaptive formula is found to be the most accurate with an average maximum index of Refraction Error of 2.91 × 10−6 within the visible band.
Ling Yeung - One of the best experts on this subject based on the ideXlab platform.
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correlation between higher order aberrations and visual acuity recovery cohort after spectacles treatment for pediatric refractive amblyopia a pilot study using idesign measurement
PLOS ONE, 2020Co-Authors: Chunghsin Tseng, Chungying Huang, Mengling Yang, Weiyi Chen, Ling YeungAbstract:Purpose To determine the correlation between higher-order aberrations (HOAs) and best-corrected visual acuity (BCVA) recovery speed after spectacles treatment using iDesign measurements in refractive amblyopic children. Methods This is a prospective case series. Children aged from 3 to 7 years with refractive amblyopia (Landolt C equivalent < 0.8) were recruited. All participants were followed for at least 6 months after full correction of the Refraction Error by spectacles. The HOAs were measured using iDesign before and after cycloplegia at first visit and at 3-month intervals. Then correlation between BCVA recovery after treatment for 6 months and HOAs was determined. Results We analyzed 24 eyes of 12 children (mean age, 4.5 years). Baseline mean BCVA was logarithm of minimal angle of resolution (logMAR) 0.335 (Landolt C equivalent 0.46), which improved to logMAR 0.193 (Landolt C equivalent 0.64) after treatment with full-correction spectacles for 6 months. The amblyopic eye BCVA recovery was negatively correlated with tetrafoil with/without cycloplegia (P = 0.006 and 0.022, respectively) and trefoil with cycloplegia (P = 0.049). Conclusions trefoil and tetrafoil measured with iDesign negatively correlates with the BCVA recovery speed of refractive amblyopic eyes after spectacles treatment in this pilot study. The current study results may aid in further investigation for diagnosis and treatment of refractory refractive and idiopathic amblyopia.
Li Wei - One of the best experts on this subject based on the ideXlab platform.
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research on large scale channel model and improved algorithm of atmospheric Refraction Error
Computer Simulation, 2010Co-Authors: Li WeiAbstract:By comparing with the Okumra - Hata model,Longley - Rice channel model is put forward which suits for large scale model.Longley - Rice channel model modifies the atmospheric Refraction Error by the equivalent earth radius method,which is inexact and does not agree with actual propagation path.This article make improvements on the atmospheric Refraction Error correction method of the Longley - Rice channel model.The effectiveness of improved methods is proved by simulation comparing with measured data.
Zhipeng Dong - One of the best experts on this subject based on the ideXlab platform.
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Refraction Error correction of airborne lidar bathymetry data considering sea surface waves
International Journal of Applied Earth Observation and Geoinformation, 2021Co-Authors: Kai Guo, Yanxiong Liu, Ziwen Tian, Qiuhua Tang, Zhipeng DongAbstract:Abstract Airborne Light Detection And Ranging (LiDAR) Bathymetry (ALB) has an unparalleled advantage in integrated sea-land measurements, especially in the acquisition of topographic data in shallow water areas. Sea surface waves are an important factor affecting the quality of ALB data. This paper presents a method that strictly corrects the sea surface wave-induced Refraction Error for each seabed laser pulse without any complex modeling of the sea surface. In this method, an adaptive neighborhood selection method is first used to calculate the normal sea surface at the moment when a laser pulse enters the water, and then a laser pulse Refraction Error correction model considering sea surface waves is constructed. The distance condition equation, the angle condition equation and the coplanar condition equation are established based on Snell's law and the geometric relationship among the incident laser pulse, the normal vector of the wavy sea surface and the actual refracted ray in order to calculate the coordinates of each laser point at the seabed after Refraction Error correction. The experimental results show that sea surface waves have a significant impact on the three-dimensional point cloud coordinates of the underwater topography. Even in calm sea conditions, the plane coordinate displacement Error of the seabed point caused by the sea surface waves may reach the meter level, and the depth coordinate displacement Error can also exceed 0.2 m. The corrected displacement Errors of the planimetric coordinates are significantly greater than the corrected displacement Errors of the depth coordinates, which can effectively improve the quality of the ALB data.
Kai Guo - One of the best experts on this subject based on the ideXlab platform.
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Refraction Error correction of airborne lidar bathymetry data considering sea surface waves
International Journal of Applied Earth Observation and Geoinformation, 2021Co-Authors: Kai Guo, Yanxiong Liu, Ziwen Tian, Qiuhua Tang, Zhipeng DongAbstract:Abstract Airborne Light Detection And Ranging (LiDAR) Bathymetry (ALB) has an unparalleled advantage in integrated sea-land measurements, especially in the acquisition of topographic data in shallow water areas. Sea surface waves are an important factor affecting the quality of ALB data. This paper presents a method that strictly corrects the sea surface wave-induced Refraction Error for each seabed laser pulse without any complex modeling of the sea surface. In this method, an adaptive neighborhood selection method is first used to calculate the normal sea surface at the moment when a laser pulse enters the water, and then a laser pulse Refraction Error correction model considering sea surface waves is constructed. The distance condition equation, the angle condition equation and the coplanar condition equation are established based on Snell's law and the geometric relationship among the incident laser pulse, the normal vector of the wavy sea surface and the actual refracted ray in order to calculate the coordinates of each laser point at the seabed after Refraction Error correction. The experimental results show that sea surface waves have a significant impact on the three-dimensional point cloud coordinates of the underwater topography. Even in calm sea conditions, the plane coordinate displacement Error of the seabed point caused by the sea surface waves may reach the meter level, and the depth coordinate displacement Error can also exceed 0.2 m. The corrected displacement Errors of the planimetric coordinates are significantly greater than the corrected displacement Errors of the depth coordinates, which can effectively improve the quality of the ALB data.