Automated placement of supplementary contour lines

ABSTRACT

Supplementary contour lines are placed between regular contour lines to visualize small but important forms that regular contour lines are unable to show. On topographic maps, typical forms are hillcrests, depressions, saddles, terraces, banks, and levees. No automated method for the selection of supplementary contour lines has been described so far. We document cartographic design principles for the selection of supplementary contour lines for topographic maps, and present an automated method for their placement. Results of the automated method are similar to manually placed supplementary contour lines. Our method helps map authors to create contour line maps that more effectively illustrate relevant small details in maps showing terrain elevation or other scalar fields.

KEYWORDS:

• Supplementary contour line
• intermediate contour
• isoline
• isarithm
• isohypse

Acknowledgments

The authors thank the anonymous reviewers for their valuable comments, Sebastian Hennig for his help with creating some of the figures, Jürg Gilgen of the Swiss Federal Office of Topography and Stefan Räber of the Institute of Cartography and Geoinformation of ETH Zurich for their comments and feedback on maps with automated supplementary contour lines, and Jane Darbyshire, Oregon State University, for copy-editing this manuscript.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Notes on contributors

Timofey Samsonov

Timofey Samsonov is a leading researcher at Lomonosov Moscow State University (MSU), Faculty of Geography, Moscow, Russia. He works in the field of automated cartography with a particular interest in algorithms for cartographic generalization and visualization of spatial data.

Sergey Koshel

Sergey Koshel is a leading researcher at Lomonosov Moscow State University (MSU), Faculty of Geography, Moscow, Russia. His research interests include digital terrain modeling and spatial interpolation.

Dmitry Walther

Dmitry Walther is currently a Bachelor student at Lomonosov MSU, Faculty of Geography, Moscow, Russia.

Bernhard Jenny

Bernhard Jenny is an Associate Professor at Monash University, Melbourne,  Australia. His research focuses on immersive geovisualisation, map design, map projections, and terrain mapping in 2D and 3D.