Overlaying transparency images including pixels corresponding to different heirarchical levels over a geographic map

An article comprising at least one machine-readable storage medium storing instructions that upon execution cause a system to:

• recursively divide a data space containing data records into progressively smaller partitions corresponding to different hierarchical levels, where the data records contain corresponding values of an attribute and are associated with location information;
• generate transparency images containing respective groups of pixels representing data records in the data space and the smaller partitions, wherein the transparency images are at a plurality of hierarchical levels that correspond to different zoom levels of a geographic map;
• and
• overlay, over the geographic map, at least one of the transparency images at a dynamically-selected one of the hierarchical levels according to which of a plurality of zoom levels is selected by a user in zooming of the geographic map, wherein the at least one transparency image is automatically selected without user input.

A system comprising:

• at least one processor to:
• receive data records containing corresponding values of an attribute and associated with location information;
• generate hierarchical levels of transparency images, where each of the transparency images includes corresponding pixels that represent the respective data records, and where the transparency images at different ones of the hierarchical levels correspond to different zoom levels of a geographic map;
• and
• overlay, over the geographic map, at least one of the transparency images at a dynamically-selected one of the hierarchical levels according to which of the zoom levels is is selected by a user in zooming of the geographic map, wherein the at least one transparency image is automatically selected without user input.