A valid image-processing algorithm of weld pool surface reconstruction according to an input image of weld pool based on shape from shading(SFS)in computer vision is presented.The weld pool surface information is rela...A valid image-processing algorithm of weld pool surface reconstruction according to an input image of weld pool based on shape from shading(SFS)in computer vision is presented.The weld pool surface information is related to the backside weld width,which is crucial to the quality of weld joint.The image of weld pool is recorded with an optical sensing method.Firstly,the reflectance map model,which specifies the imaging process,is estimated.Then,the algorithm of weld pool surface reconstruction based on SFS is implemented by iteration scheme and speeded by hierarchical structure.The results indicate the accuracy and effectiveness of the approach.展开更多
In many cases,the Digital Surface Models(DSMs)and Digital Elevation Models(DEMs)are obtained with Light Detection and Ranging(LiDAR)or stereo matching.As an active method,LiDAR is very accurate but expensive,thus ofte...In many cases,the Digital Surface Models(DSMs)and Digital Elevation Models(DEMs)are obtained with Light Detection and Ranging(LiDAR)or stereo matching.As an active method,LiDAR is very accurate but expensive,thus often limiting its use in small-scale acquisition.Stereo matching is suitable for large-scale acquisition of terrain information as the increase of satellite stereo sensors.However,underperformance of stereo matching easily occurs in textureless areas.Accordingly,this study proposed a Shading Aware DSM GEneration Method(SADGE)with high resolution multi-view satellite images.Considering the complementarity of stereo matching and Shape from Shading(SfS),SADGE combines the advantage of stereo matching and SfS technique.First,an improved Semi-Global Matching(SGM)technique is used to generate an initial surface expressed by a DSM;then,it is refined by optimizing the objective function which modeled the imaging process with the illumination,surface albedo,and normal object surface.Different from the existing shading-based DEM refinement or generation method,no information about the illumination or the viewing angle is needed while concave/convex ambiguity can be avoided as multi-view images are utilized.Experiments with ZiYuan-3 and GaoFen-7 images show that the proposed method can generate higher accuracy DSM(12.5-56.3%improvement)with sound overall shape and temporarily detailed surface compared with a software solution(SURE)for multi-view stereo.展开更多
在利用单幅影像的明暗恢复形状(Shape From Shading,SFS)三维重构算法的基础上,提出同时考虑外界辐射源和目标自身红外辐射的IR-SFS(infrared-SFS)算法。首先通过分析SFS算法原理和空间目标的红外成像特性,建立IR-SFS辐射方程并进行了...在利用单幅影像的明暗恢复形状(Shape From Shading,SFS)三维重构算法的基础上,提出同时考虑外界辐射源和目标自身红外辐射的IR-SFS(infrared-SFS)算法。首先通过分析SFS算法原理和空间目标的红外成像特性,建立IR-SFS辐射方程并进行了仿真研究,然后利用温度场估计获得红外差值图,在人工合成的理想半球体、半圆柱体卫星红外影像上进行算法测试,并以美国STS107真实红外影像作为实验目标进行三维重建。实验结果表明,所提出IR-SFS算法经过参数优化后,与原SFS算法相比,重建模型的峰值信噪比更高,对STS107顶部舱门、尾翼、机舱、机舱内方形部件具有更佳显示度,整体效果得到明显改善。展开更多
通过视觉方法获取形状在科学研究及工程实践中有着重要作用,灰度图像是最容易获取的视觉信息之一。目前由灰度重构的形状(SFS,shape from shading)受到了广泛的关注,但现有的算法稳定性差、效率低,一直阻碍着SFS方法的推广应用。受近期...通过视觉方法获取形状在科学研究及工程实践中有着重要作用,灰度图像是最容易获取的视觉信息之一。目前由灰度重构的形状(SFS,shape from shading)受到了广泛的关注,但现有的算法稳定性差、效率低,一直阻碍着SFS方法的推广应用。受近期的视觉心理学研究成果的启发,针对SFS问题,从局部分析入手,即:在图像上,在每一灰度极值点附近,根据灰度单调变化的情况,形成一个椭圆形邻域,对应着表面凹凸区;在每一椭圆域上,形状可用抛物面逼近,其参数可由局部辐射度约束求解;整个图像被椭圆形邻域覆盖,这些覆盖可构成一个二维流形;借助于流形上单位分解函数,各局部抛物面粘合在一起,形成光滑的整体形状;总体形状在整幅图像的灰度约束下再进行全局优化,可得到最终的重构结果。给出了初步算例,算法的稳定性和效率均有大幅度提高。展开更多
目前采用的从明暗恢复形状(shape from shading,SFS)法存在对物体表面光滑度要求高,对噪声敏感等问题,为此,提出了一种基于数学形态学的SFS法,通过数学形态学提取图像灰度函数的峰、谷、脊、沟,鞍等形状特征,并采用球状点假设法确定物...目前采用的从明暗恢复形状(shape from shading,SFS)法存在对物体表面光滑度要求高,对噪声敏感等问题,为此,提出了一种基于数学形态学的SFS法,通过数学形态学提取图像灰度函数的峰、谷、脊、沟,鞍等形状特征,并采用球状点假设法确定物体的表面方向,恢复物体三维表面。实验表明,该方法具有更好的精度和抗噪性能。展开更多
提出一种融合RGBD(red,green,blue and depth)信息和明暗恢复形状(SFS)的三维(3D)数字化方法。首先在室内自然光环境下使用Kinect深度相机获取被测物体表面的彩色图和深度图,其次对采集到的深度图进行双边滤波处理,并估计处理后深度图...提出一种融合RGBD(red,green,blue and depth)信息和明暗恢复形状(SFS)的三维(3D)数字化方法。首先在室内自然光环境下使用Kinect深度相机获取被测物体表面的彩色图和深度图,其次对采集到的深度图进行双边滤波处理,并估计处理后深度图的表面法向量,然后建立光照模型并对其求解,最后构建全局代价函数,以完成对目标物体深度信息的优化求解。实验结果表明:该方法可以在室内自然光环境下较好地恢复出重建物体的细节信息。展开更多
The number of constraints imposed on the sur- face, the light source, the camera model and in particular the initial information makes shape from shading （SFS） very dif- ficult for real applications. There are a con...The number of constraints imposed on the sur- face, the light source, the camera model and in particular the initial information makes shape from shading （SFS） very dif- ficult for real applications. There are a considerable number of approaches which require an initial data about the 3D ob- ject such as boundary conditions （BC）. However, it is difficult to obtain these information for each point of the object Edge in the image, thus the application of these approaches is lim- ited. This paper shows an improvement of the Global View method proposed by Zhu and Shi [1]. The main improvement is that we make the resolution done automatically without any additional information on the 3D object. The method in- volves four steps. The first step is to determine the singular curves and the relationship between them. In the second step, we generate the global graph, determine the sub-graphs, and determine the partial and global configuration. The proposed method to determine the convexity and the concavity of the singular curves is applied in the third step. Finally, we apply the Fast-Marching method to reconstruct the 3D object. Our approach is successfully tested on some synthetic and real im- ages. Also, the obtained results are compared and discussed with some previous methods.展开更多
基金supported by National Natural Science Foundation of China(No.50575144).
文摘A valid image-processing algorithm of weld pool surface reconstruction according to an input image of weld pool based on shape from shading(SFS)in computer vision is presented.The weld pool surface information is related to the backside weld width,which is crucial to the quality of weld joint.The image of weld pool is recorded with an optical sensing method.Firstly,the reflectance map model,which specifies the imaging process,is estimated.Then,the algorithm of weld pool surface reconstruction based on SFS is implemented by iteration scheme and speeded by hierarchical structure.The results indicate the accuracy and effectiveness of the approach.
基金supported by the National Natural Science Foundation of China[grant number 41801390]the National Key R&D Program of China[grant number 2018YFD1100405].
文摘In many cases,the Digital Surface Models(DSMs)and Digital Elevation Models(DEMs)are obtained with Light Detection and Ranging(LiDAR)or stereo matching.As an active method,LiDAR is very accurate but expensive,thus often limiting its use in small-scale acquisition.Stereo matching is suitable for large-scale acquisition of terrain information as the increase of satellite stereo sensors.However,underperformance of stereo matching easily occurs in textureless areas.Accordingly,this study proposed a Shading Aware DSM GEneration Method(SADGE)with high resolution multi-view satellite images.Considering the complementarity of stereo matching and Shape from Shading(SfS),SADGE combines the advantage of stereo matching and SfS technique.First,an improved Semi-Global Matching(SGM)technique is used to generate an initial surface expressed by a DSM;then,it is refined by optimizing the objective function which modeled the imaging process with the illumination,surface albedo,and normal object surface.Different from the existing shading-based DEM refinement or generation method,no information about the illumination or the viewing angle is needed while concave/convex ambiguity can be avoided as multi-view images are utilized.Experiments with ZiYuan-3 and GaoFen-7 images show that the proposed method can generate higher accuracy DSM(12.5-56.3%improvement)with sound overall shape and temporarily detailed surface compared with a software solution(SURE)for multi-view stereo.
文摘在利用单幅影像的明暗恢复形状(Shape From Shading,SFS)三维重构算法的基础上,提出同时考虑外界辐射源和目标自身红外辐射的IR-SFS(infrared-SFS)算法。首先通过分析SFS算法原理和空间目标的红外成像特性,建立IR-SFS辐射方程并进行了仿真研究,然后利用温度场估计获得红外差值图,在人工合成的理想半球体、半圆柱体卫星红外影像上进行算法测试,并以美国STS107真实红外影像作为实验目标进行三维重建。实验结果表明,所提出IR-SFS算法经过参数优化后,与原SFS算法相比,重建模型的峰值信噪比更高,对STS107顶部舱门、尾翼、机舱、机舱内方形部件具有更佳显示度,整体效果得到明显改善。
文摘通过视觉方法获取形状在科学研究及工程实践中有着重要作用,灰度图像是最容易获取的视觉信息之一。目前由灰度重构的形状(SFS,shape from shading)受到了广泛的关注,但现有的算法稳定性差、效率低,一直阻碍着SFS方法的推广应用。受近期的视觉心理学研究成果的启发,针对SFS问题,从局部分析入手,即:在图像上,在每一灰度极值点附近,根据灰度单调变化的情况,形成一个椭圆形邻域,对应着表面凹凸区;在每一椭圆域上,形状可用抛物面逼近,其参数可由局部辐射度约束求解;整个图像被椭圆形邻域覆盖,这些覆盖可构成一个二维流形;借助于流形上单位分解函数,各局部抛物面粘合在一起,形成光滑的整体形状;总体形状在整幅图像的灰度约束下再进行全局优化,可得到最终的重构结果。给出了初步算例,算法的稳定性和效率均有大幅度提高。
文摘目前采用的从明暗恢复形状(shape from shading,SFS)法存在对物体表面光滑度要求高,对噪声敏感等问题,为此,提出了一种基于数学形态学的SFS法,通过数学形态学提取图像灰度函数的峰、谷、脊、沟,鞍等形状特征,并采用球状点假设法确定物体的表面方向,恢复物体三维表面。实验表明,该方法具有更好的精度和抗噪性能。
文摘提出一种融合RGBD(red,green,blue and depth)信息和明暗恢复形状(SFS)的三维(3D)数字化方法。首先在室内自然光环境下使用Kinect深度相机获取被测物体表面的彩色图和深度图,其次对采集到的深度图进行双边滤波处理,并估计处理后深度图的表面法向量,然后建立光照模型并对其求解,最后构建全局代价函数,以完成对目标物体深度信息的优化求解。实验结果表明:该方法可以在室内自然光环境下较好地恢复出重建物体的细节信息。
文摘The number of constraints imposed on the sur- face, the light source, the camera model and in particular the initial information makes shape from shading （SFS） very dif- ficult for real applications. There are a considerable number of approaches which require an initial data about the 3D ob- ject such as boundary conditions （BC）. However, it is difficult to obtain these information for each point of the object Edge in the image, thus the application of these approaches is lim- ited. This paper shows an improvement of the Global View method proposed by Zhu and Shi [1]. The main improvement is that we make the resolution done automatically without any additional information on the 3D object. The method in- volves four steps. The first step is to determine the singular curves and the relationship between them. In the second step, we generate the global graph, determine the sub-graphs, and determine the partial and global configuration. The proposed method to determine the convexity and the concavity of the singular curves is applied in the third step. Finally, we apply the Fast-Marching method to reconstruct the 3D object. Our approach is successfully tested on some synthetic and real im- ages. Also, the obtained results are compared and discussed with some previous methods.
