1. A method comprising: generating a hierarchically arranged data structure to be used when classifying one or more objects included within a query image based on multi-resolution query feature descriptor extracted from the query image at a first scale space resolution and a second scale space resolution, wherein the hierarchically arranged data structure represents a first query feature descriptor of the multi-resolution feature descriptor extracted at the first scale space resolution and a second corresponding query feature descriptor of the multi-resolution feature descriptor extracted at the second scale space resolution hierarchically arranged according to the first scale space resolution and the second scale space resolution; and performing a visual search based on the generated data structure.