1. A method of classifying objects in a scene, captured by a camera, the method comprising: determining a likelihood of first set of states for the objects in the scene, each of the first set of states being a classification of one of the objects in the scene; partitioning a solution space based on the determined likelihood of the first set of states, each partition of the solution space representing combinations of the classifications of the objects in the scene; applying the partitioning of the solution space to a solution space of a second set of states, each partition of the solution space of the second set of states representing combinations of the classifications of a subset of objects in the scene; determining a likelihood of the second set of states for the subset of the objects in the scene, each state of the second set of states being a classification of one of the subset of objects in the scene; and classifying at least one of the subset of objects in the scene according to the determined likelihood of the second set of states and the partitioning of the solution space of the second set of states.