1. A method for performing direct rendering of a multi-volume data, comprising: determining whether a volume of the multi-volume data is one of active and inactive via interaction with a ray for the multi-volume data; recording in triplicate a starting point and an end point of the ray for an eyespace; repeating the determining whether the volume is one of active and inactive via interaction with a ray for the multi-volume data and the recording in triplicate the starting point and the end point of the ray for an eyespace for all volumes of the multi-volume data; providing triples from all volumes to an array; sorting the array to create a sorted triples list array; breaking the ray into a plurality of segments using the sorted triples list array; determining which volumes are active for each of the segments via an active volume list; and sampling each segment of the ray to acquire an accumulated result, wherein multi reduced path octree structures are used on each volume during the determining whether the volume of the multi-volume data is one of active and inactive.