2. The distributed data annotation server system of claim 1 , wherein the distributed data annotation application further configures the processor to estimate the ground truth for at least one piece of source data using the source data metadata and the annotator metadata by iteratively: updating source data metadata for at least one piece of source data based upon at least the previously generated source data metadata and annotator metadata; updating annotator metadata for at least one annotator based upon at least the previously generated source data metadata and annotator metadata; and estimating the ground truth for at least one piece of source data using the updated source data metadata and the updated annotator metadata when a termination condition occurs.
2. The distributed data annotation server system of claim 1 , wherein the distributed data annotation application further configures the processor to estimate the ground truth for at least one piece of source data using the source data metadata and the annotator metadata by iteratively: updating source data metadata for at least one piece of source data based upon at least the previously generated source data metadata and annotator metadata; updating annotator metadata for at least one annotator based upon at least the previously generated source data metadata and annotator metadata; and estimating the ground truth for at least one piece of source data using the updated source data metadata and the updated annotator metadata when a termination condition occurs. 3. The distributed data annotation server system of claim 2 , wherein the distributed data annotation application configures the processor to determine source data characteristics in the source data metadata and identify annotator characteristics in the annotator metadata using an iterative maximum a posteriori estimation and the received annotations.