1. A distributed data annotation server system, comprising: at least one storage device configured to store source data, one or more annotators, annotation tasks, and a distributed data annotation application; and a processor; wherein the distributed data annotation application configures the processor to: receive source data, where the source data comprises one or more pieces of source data; select one or more annotators for at least one piece of source data; create one or more annotation tasks for the selected annotators and at least one piece of source data; request one or more annotations for at least one piece of source data using the created annotation tasks; receive annotations for at least one piece of source data; determine source data metadata for at least one piece of source data using the received annotations, where the source data metadata includes source data characteristics; generate annotator metadata for at least one annotator using the received annotations and at least one piece of source data, where the annotator metadata includes identified annotator characteristics; and estimate the ground truth for at least one piece of source data using the source data metadata and the annotator metadata.