Gray tones and line plotter shades are two common area symbols used to display quantitative data on maps. Since these two symbols are visually quite different from one another, the question arises as to whether or not the overall spatial message communicated by maps using these symbols would be identical for a particular data set. As a preliminary to answering this broader question, an experiment was performed in which subjects matched individual line plotter shades with gray tones. The purpose of this experiment was twofold: 1) determine the general relation between the two symbol types, and 2) determine the ease with which line plotter symbols could serve as substitutes for gray tones. The results revealed first that the general relation is essentially linear; a gray tone of a given percent area inked can be represented by a line plotter shade of about the same percent area inked. As such, the results support those obtained in previous gray scale studies. Secondly, both the actual response data and comments provided by subjects indicate that line plotter symbols are difficult to match with gray tones. This difficulty may portend differences for the overall spatial message communicated by these two symbol types.
Bibliographical noteFunding Information:
Dr. Slocum is an Assistant Professor in the Department of Geography, University of Kansas, Lawrence, Kansas 66045. Dr. McMaster is an Assistant Professor in the Department of Geography, University of California, Los Angeles, California 90024. This investigation was supported by University of Kansas General Research Allocation #3386-20-0038. The authors also wish to thank Linus Smith for his assistance in data collection.
- Area symbol maps
- Gray curves
- Gray tones
- Line plotter shadings