Targets_HumanConf: one of {1,2,3,4} indicating target visibility. That is, whether the human truthers felt they could identify the target in the data. Scale of: 1 visible, 2 probably visible, 3 possibly visible, 4 not visible
Targets_HumanCat: one of {0,1,2} indicating occlusion category. 0 unoccluded, 1 part or fully in shadow but no tree occlusion, 2 part or full occlusion by tree