A comparison of spatial query processing techniques for native and parameter spaces

Spatial queries can be evaluated in native space or in a parameter space. In the latter case, data objects are transformed into points and query objects are transformed into search regions. The requirement for different data and query representations may prevent the use of parameter-space searching in some applications. Native-space and parameter-space searching are compared in the context of a z order-based spatial access method. Experimental results show that when there is a single query object, searching in parameter space can be faster than searching in native space, if the data and query objects are large enough, and if sufficient redundancy is used for the query representation. The result is, however, less accurate than the native space result. When there are multiple query objects, native-space searching is better initially, but as the number of query objects increases, parameter space searching with low redundancy is superior. Native-space searching is much more accurate for multiple-object queries.