  Global overlay maps of science use base maps that are overlaid by specific
data (from single researchers, institutions, or countries) for visualizing
scientific performance such as field-specific paper output. A procedure to
create global overlay maps using OpenAlex is proposed. Six different global
base maps are provided. Using one of these base maps, example overlay maps for
one individual (the first author of this paper) and his research institution
are shown and analyzed. A method for normalizing the overlay data is proposed.
Overlay maps using raw overlay data display general concepts more pronounced
than their counterparts using normalized overlay data. Advantages and
limitations of the proposed overlay approach are discussed.
