Page 20 - 3DF Zephyr

- pictures get a high percentage of overlap (70% - 80%); It is recommended to increase keypoints density when: - Cameras are not correctly oriented; - There are some pictures too close and too far from the subject/scene; - The dataset counts a few photos that have a low percentage of overlap; - The subject/scene has a uniform surface and no texture (a white wall for instance); Matching Type: allows to select different kinds of matches between the keypoints in the images. The accurate option requires more time to be completed; Matching Stage Depth: set-up how many matches are performed on the images between the keypoints. By setting this parameter to the higher value, the capability to align multiple images at the same time is going to increase just like computation time. It is recommended to decrease the depth value of the matching stage when: - it is required a high computing speed; - The distance between the camera and subject is not high; - The overlap percentage between different shots is high (70% - 80%); It is recommended to increase the depth value of the matching phase when: - Cameras are not correctly oriented; - There are some pictures too close and too far from the subject/scene; - The dataset counts a few photos that have a low percentage of overlap; - The subject/scene has a uniform surface and no texture (a white wall for instance); Reprojection Error Tolerance: it checks the maximum reprojection error allowed (in pixels) for each point during geometrical reconstruction step and the minimum number of points required to merge two clusters of images together. By selecting strict option it is possible to get a more accurate reconstruction while wide option increases the chance to orient the cameras which would otherwise be discarded. It is recommended to reduce the reprojection error tolerance when: - Reconstruction is not able to converge; It is recommended to increase the reprojection error tolerance when: - Not all cameras are properly oriented; Rematching: enables or disable an additional rematching step at the end of the SfM phase, plus an additional bundle adjustment, in order to improve accuracy. Reconstruction Engine: 3DF Samantha supports both incremental and global reconstructions pipeline. The global pipeline tries to solve the orientation problem