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3D表面重构中的共平面约束及其解的空间分析
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作者 于永彦 王志坚 《山东农业大学学报(自然科学版)》 CSCD 2015年第5期747-752,共6页
基于单图像的3D重构因其先天性约束不足和潜在的巨大价值成为计算机视觉领域的研究热点,被广泛应用于航空航天、机械制造、医疗、考古、地质、犯罪现场复原、建筑设计、城市规划等领域。针对图像中几何元素的共平面性可提供景深信息的特... 基于单图像的3D重构因其先天性约束不足和潜在的巨大价值成为计算机视觉领域的研究热点,被广泛应用于航空航天、机械制造、医疗、考古、地质、犯罪现场复原、建筑设计、城市规划等领域。针对图像中几何元素的共平面性可提供景深信息的特点,提出一种基于交叉曲线共平面性约束的3D重构方案,即对于不平行于投影方向的某一个平面,根据其所含曲线与另一平面中某曲线的交叉构型构造一个线性系统,当一组这样的交叉曲线位于拟求解表面时,可获得精确解。对于含噪系统,要求测得的交点远离平坦面,增加新的约束条件,定义表面的平坦度度量模型,使用SVD法获得极小化线性系统的代数误差的逼近解。由于利用正投影和透视投影的等价性,可将透视投影转化为正投影,从而将这两种投影下的3D重构规划一个框架中。实验表明,这种方法大大提高了3D重构的健壮性,对噪声的敏感性小,可适用于完全未标定结构光等真实场景。 展开更多
关键词 共平面性 线性系统 表面平坦度 解空间 3D重构
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Influence of advection on the characteristics of turbulence over uneven surface in the oasis and the Gobi Desert 被引量:3
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作者 CHEN JinBei HU YinQiao +1 位作者 Lü ShiHua YU Ye 《Science China Earth Sciences》 SCIE EI CAS 2014年第9期2242-2258,共17页
Utilizing experimental data of the atmospheric surface layer in the Gobi Oasis of Jinta in a comparative study, we demonstrate that under the condition of unstable stratification, the normalization variances of temper... Utilizing experimental data of the atmospheric surface layer in the Gobi Oasis of Jinta in a comparative study, we demonstrate that under the condition of unstable stratification, the normalization variances of temperature in the oasis and Gobi Desert meetφs (z∧)= φθ(Z/∧) =αθ(-Z/ ∧)-1/3 while normalization variances of both humidity and CO2 in the oasis meet φ(Z/∧)= αs (1 - βs z /∧)-1/3 ; the normalization variance of temperature in the oasis is large due to disturbance by advection, whereas variance of CO2 in the Gobi Desert has certain degree of deviation relative to Monin-Obukhov (M-O) scaling, and humidity variance completely deviates from variance M-O scaling. The above result indicates that under the condition of advection, hu-midity variance meets the relation δ2 sm=D2 δ2SA + δ2SB and it is determined by relative magnitude of scalar variance of ad- midity variance meets the relation δsm = D2δsA + δsB vection transport. Our study reveals that, if the scalar variance of humidity or CO2 transported by advection is much larger than local scalar variance, observation value of scalar variance will deviate from M-O scaling; when scalar variance of advection transport is close to or less than local scalar variance, the observation value of scalar variance approximately meets M-O scal- ing. 展开更多
关键词 atmospheric surface layer (ASL) turbulence similarity theory advection uneven surface
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