RTree is a spatial indexing strategy that involves building a tree of bounding boxes that support arbitrary range searches. RTrees are efficient for geospatial data but can be extended to support any data that is amenable to range search queries.
Conversant RTree is a hyperdimensional implementation of RTree that supports data with arbitrarily large numbers of orthogonal relations.
Maven users can incorporate Conversant R-Tree the usual way.
<dependency>
<groupId>com.conversantmedia</groupId>
<artifactId>rtree</artifactId>
<version>1.0.1</version>
</dependency>