计算机视觉12 6 基于特征的图像对准.ppt

* * * * * * * * * * * * * * * * * * * * * * * * * * * * * Finding the panoramas Finding the panoramas Finding the panoramas Finding the panoramas Parameterise each camera by rotation and focal length This gives pairwise homographies Homography for Rotation Bundle Adjustment New images initialised with rotation, focal length of best matching image Bundle Adjustment New images initialised with rotation, focal length of best matching image Multi-band Blending Burt Adelson 1983 Blend frequency bands over range ? l Results 增强现实（Augmented Reality） Demo1 Demo2 Demo3 增强现实 * CV:Calibration * 位姿估计----增强现实 第一次作业: 图像拼接(任选) 编写自己的图像拼接程序 将程序放在个人信箱的网络硬盘中 工具: Matlab or OpenCV 时间：课程结束之前 * CV:Calibration * 第一次作业: 增强现实（任选） 编写自己的增强现实程序 将程序放在个人信箱的网络硬盘中 工具: ARTOOLKIT /artoolkit/ 时间：课程结束之前 * CV:Calibration * * * * * * * * * * * * * * * * * * * RANSAC RANSAC loop: Randomly select a seed group of matches Compute transformation from seed group Find inliers to this transformation If the number of inliers is sufficiently large, re-compute least-squares estimate of transformation on all of the inliers Keep the transformation with the largest number of inliers RANSAC example: Translation Putative matches Select one match, count inliers RANSAC example: Translation Select one match, count inliers RANSAC example: Translation Select translation with the most inliers RANSAC example: Translation RANSAC的问题 在许多实际应用中，外点所占的比例很高 (90% 以上) 另一种改进方法: Hough transform Hough transform Recall: Generalized Hough transform B. Leibe, A. Leonardis, and B. Schiele, Combined Object Categorization and Segmentation with an Implicit Shape Model, ECCV Workshop on Statistical Learning in Computer Vision 2004 model visual codeword withdisplacement vectors test image Hough transform 假如提取的特征具有尺度和旋转不变性 这样单个特征匹配就能提供一种可能的对准 (translation, scale, orientation) David G. Lowe. Distinctive image features from scale-invariant keypoints.” IJCV 60 (2), pp. 91-110, 2004. model 假如提取的特征具有尺度和旋转不变性 这样单个特征匹配就能提供