Factorization methods for computation of nonrigid structure have limited practicality, and work well only when there is large enough camera motion between frames, with long sequences and limited or no occlusions. We show that typical nonrigid structure can often be approximated well as locally rigid sub-structures in time and space. Specifically, we assume that: 1) the structure can be approximated as rigid in a short local time window and 2) some point pairs stay relatively rigid in space, maintaining a fixed distance between them during the sequence. We first use the triangulation constraints in rigid SFM over a sliding time window to get an initial estimate of the nonrigid 3D structure. We then automatically identify relatively rigid point pairs in this structure, and use their length-constancy simultaneously with triangulation constraints to refine the structure estimate. Unlike factorization methods, the structure is estimated independent of the camera motion computation, adding to the simplicity and stability of the approach. Further, local factorization inherently handles significant natural occlusions gracefully, performing much better than the state-of-the art. We show more stable and accurate results as compared to the state-of-the art on even short sequences starting from 15 frames only, containing camera rotations as small as 2 degree and up to 50% missing data.
| Author(s): | Rehan, Ali and Zaheer, Aamer and Akhter, Ijaz and Saeed, Arfah and Mahmood, Bilal and Usmani, Muhammad and Khan, Sohaib |
| Book Title: | Proceedings Winter Conference on Applications of Computer Vision |
| Pages: | 69-74 |
| Year: | 2014 |
| Month: | March |
| Publisher: | IEEE |
| Bibtex Type: | Conference Paper (inproceedings) |
| Address: | Steamboat Springs, CO, USA |
| Event Name: | IEEE Winter Conference on Applications of Computer Vision (WACV) |
| Event Place: | Steamboat Springs, CO, USA |
| URL: | http://ieeexplore.ieee.org/xpl/articleDetails.jsp?arnumber=6836116&searchWithin%3DAkhter%26punumber%3D6823792%26sortType%3Dasc_p_Sequence%26filter%3DAND%28p_IS_Number%3A6835728%29%26rowsPerPage%3D100 |
| Electronic Archiving: | grant_archive |
| How Published: | open access |
BibTex
@inproceedings{Rehan_wacv14,
title = {NRSfM using Local Rigidity},
booktitle = {Proceedings Winter Conference on Applications of Computer Vision},
abstract = {Factorization methods for computation of nonrigid structure have limited practicality, and work well only when there is large enough camera motion between frames, with long sequences and limited or no occlusions. We show that typical nonrigid structure can often be approximated well as locally rigid sub-structures in time and space. Specifically, we assume that: 1) the structure can be approximated as rigid in a short local time window and 2) some point pairs stay relatively rigid in space, maintaining a fixed distance between them during the sequence. We first use the triangulation constraints in rigid SFM over a sliding time window to get an initial estimate of the nonrigid 3D structure. We then automatically identify relatively rigid point pairs in this structure, and use their length-constancy simultaneously with triangulation constraints to refine the structure estimate. Unlike factorization methods, the structure is estimated independent of the camera motion computation, adding to the simplicity and stability of the approach. Further,
local factorization inherently handles significant natural occlusions gracefully, performing much better than the state-of-the art. We show more stable and accurate results as compared to the state-of-the art on even short sequences starting from 15 frames only, containing camera rotations
as small as 2 degree and up to 50% missing data.},
pages = {69-74},
howpublished = {open access},
publisher = {IEEE },
address = {Steamboat Springs, CO, USA},
month = mar,
year = {2014},
slug = {rehan_wacv14},
author = {Rehan, Ali and Zaheer, Aamer and Akhter, Ijaz and Saeed, Arfah and Mahmood, Bilal and Usmani, Muhammad and Khan, Sohaib},
url = {http://ieeexplore.ieee.org/xpl/articleDetails.jsp?arnumber=6836116&searchWithin%3DAkhter%26punumber%3D6823792%26sortType%3Dasc_p_Sequence%26filter%3DAND%28p_IS_Number%3A6835728%29%26rowsPerPage%3D100},
month_numeric = {3}
}