Vision based target tracking using tracklets
A non-hierarchical and iteratively updated tracking system includes a first module for creating an initial trajectory model for multiple targets from a set of received image detections. A second module is connected to the first module to provide identification of multiple targets using a target model, and a third module is connected to the second module to solve a joint object function and maximal condition probability for the target module. A tracklet module can update the first module trajectory module, and after convergence, output a trajectory model for multiple targets.
1. A non-hierarchical and iteratively updated tracking system, comprising:
a processor; and
system memory coupled to the processor and storing instructions configured to cause the processor to:
derive trajectory models for multiple targets from a set of received image detections;
identify targets, from among the multiple targets, using a target model including solving a joint object function and maximal condition probability for the target model dependent on a hyper-parameter set, including:
formulate the hyper-parameter set from the trajectory models;
solve a unary term describing how a hidden state value fits an observation dependent on the hyper-parameter set;
solve a pairwise term defining a probability that adjacent nodes in a graph correspond to the same label depending on the hyper-parameter set; and
merge the solution of the unary term, the solution of the pairwise term, and a normalization factor into a solution of the joint object function and maximal conditional probability;
update the trajectory models, including linking tracklets to one another based on the solution of the joint object function and maximal conditional probability;
detect trajectory convergence for the multiple targets within the updated trajectory models based on equations associated with the linked tracklets satisfying a belief threshold; and
output the updated trajectory models.
2. The iteratively updated tracking system of claim 1 , wherein instructions configured to derive trajectory models comprise instructions configured to access sliding windows initializable from at least one of a first frame and a previous sliding window.
3. The iteratively updated tracking system of claim 1 , wherein instructions configured to identify targets using a target model comprise instructions configured to identify targets using a Markov random field model.
4. The iteratively updated tracking system of claim 1 , wherein instructions configured to solve a joint object function and maximal condition probability comprise instructions configured to use a loopy belief propagation algorithm.
5. The iteratively updated tracking system of claim 1 , further comprising instructions configured to reset the number of trajectory models.
6. The iteratively updated tracking system of claim 1 , further comprising instructions configured to initialize the trajectory models.
7. An iteratively updated tracking system, comprising:
a processor; and
system memory coupled to the processor and storing instructions configured to cause the processor to
derive trajectory models for multiple targets from a set of received image detections;
identify targets, from among the multiple targets, using a Markov random field model including solving a joint object function and maximal condition probability of the Markov random field model using a loopy belief propagation algorithm depending on a hyper-parameter set, including:
formulate the hyper-parameter set from the trajectory models;
solve a unary term describing how a hidden state value fits an observation dependent on the hyper-parameter set;
solve a pairwise term defining a probability that adjacent nodes in a graph correspond to the same label depending on the hyper-parameter set; and
merge the solution of the unary term, the solution of the pairwise term, and a normalization factor into a solution of the joint object function and maximal conditional probability;
update the trajectory models, including linking tracklets to one another based on the solution of the joint object function and maximal condition probability;
detect trajectory convergence for the multiple targets within the updated trajectory models; and
output the updated trajectory models.
8. The iteratively updated tracking system of claim 7 , wherein instructions configured to derive trajectory models comprise instructions configured to access sliding windows initializable from at least one of a first frame and a previous sliding window.
9. The iteratively updated tracking system of claim 7 , wherein instructions configured to update the trajectory models comprising instructions configured to update the trajectory models based on model metric data.
10. The iteratively updated tracking system of claim 7 , wherein instructions configured to detect trajectory convergence for the multiple targets within the updated trajectory models comprise instructions configured to detect trajectory convergence for the multiple targets within the updated trajectory models based on equations associated with the linked tracklets satisfying a belief threshold.
11. The iteratively updated tracking system of claim 7 , further comprising instructions configured to reset the number of trajectory models.
12. The iteratively updated tracking system of claim 7 , further comprising instructions configured to initialize the trajectory models.
13. The iteratively updated tracking system of claim 8 , wherein instructions configured to identify targets comprises instructions configured to infer target identification for detections in a sliding window from among the sliding windows.
14. A non-hierarchical and iteratively updated tracking method, comprising:
deriving trajectory models for multiple targets from a set of received image detections;
identifying targets, from among the multiple targets using a target model including solving a joint object function and maximal condition probability for the target model dependent on a hyper-parameter set, including:
formulating the hyper-parameter set from the trajectory models;
solving a unary term describing how a hidden state value fits an observation dependent on the hyper-parameter set;
solving a pairwise term defining a probability that adjacent nodes in a graph correspond to the same label depending on the hyper-parameter set; and
merging the solution of the unary term, the solution of the pairwise term, and a normalization factor into a solution of the joint object function and maximal conditional probability;
updating the trajectory models, including linking tracklets to one another based on the solution of the joint object function and maximal conditional probability;
detecting trajectory convergence for the multiple targets within the updated trajectory models based on equations associated with the linked tracklets satisfying a belief threshold; and
outputting the updated trajectory models.
15. The method of claim 14 , wherein deriving trajectory models comprises accessing sliding windows initializable from at least one of a first frame and a previous sliding window.
16. The method of claim 14 , wherein identifying targets using a target model comprise identifying targets using a Markov random field model.
17. The method of claim 14 , wherein solving a joint object function and maximal condition probability comprises using a loopy belief propagation algorithm.
18. The method of claim 14 , further comprising resetting the number of trajectory models.
19. The method of claim 14 , further comprising initializing the trajectory models.
20. The method of claim 15 , wherein identify targets comprises inferring target identification for detections in a sliding window from among the sliding windows.