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Hopkins 155 Additional Sequences: Missing Data
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Version: April 19th, 2010

Additional sequences description
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These additional sequences are similar to the group of Checkerboard
sequences in the Hopkins 155 dataset [1], [2]. They contain the same objects and their nomenclature follows the same convention. However, in all the sequences most of the trajectories have missing points, i.e. frames for which the tracked point becomes occluded and cannot be followed by the tracker. These sequences have been used in [3], [4] and [5].

Database content
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# of sequences 		12
Avg. # of groups 	2.2
Avg. # of points 	418
Avg. # of frames 	35
Avg. % of missing data 	8.33%

File format
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The file format is analogous to the one used in the Hopkins 155. The file *_truth.mat, however, contains a the new variable m, with the information on the frames for which the points are missing:

. m: a matrix PxF (P = number of points, F = number of frames) where the p,f-th entry is 1 if the point p is visible in the frame f and zero otherwise.

References
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[1] http://www.vision.jhu.edu/data/hopkins155/

[2] R. Tron and R. Vidal.
A Benchmark for the Comparison of 3-D Motion Segmentation Algorithms.
IEEE International Conference on Computer Vision and Pattern Recognition, 2007. 

[3] R. Vidal, R. Tron, and R. Hartley.
Multiframe Motion Segmentation with Missing Data Using PowerFactorization and GPCA.
International Journal on Computer Vision, volume 79, number 1, pages 85 - 105, 2008. 

[4] S. Rao, R. Tron, Y. Ma, and R. Vidal.
Motion Segmentation via Robust Subspace Separation in the Presence of Outlying, Incomplete, or Corrupted Trajectories.
IEEE International Conference on Computer Vision and Pattern Recognition, 2008. 

[5] S. Rao, R. Tron, R. Vidal, and Y. Ma.
Motion Segmentation in the Presence of Outlying, Incomplete, or Corrupted Trajectories.
IEEE Transactions on Pattern Analysis and Machine Intelligence, 2009. 


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