Very helpful. Pinned down the world map in my kitchen to 1986-1989

Petchenik's "From Space to Place: The Psychological Achievement of Thematic Mapping" (American Cartographer 6, 12, 1979) reviews the English language literature and its attempts to define the "thematic map" and she finds all attempts problematic. She ends up arguing for a distinction "...there is the map whose meaning lies in the human experience of being-in-place" - the reference map. "...its meaning can be considered cognitively less complex." Compare to "the map whose meaning is experienced as knowing-about-space..." the thematic map. "It requires a more advanced stage of cognitive development in the spatial domain."

co-creator of the diffusion method for creating cartograms. page has C code implementing the algorithm for shp files.