T Midtbo

Division of Geomatics, NTNU


10-12 years ago the majority of maps, either on paper or in electronic media, usually were static and included few interactive operations. The legend describing the symbols on the map was, with few exceptions, located outside the map itself. With the introduction of the Internet and the World Wide Web (WWW) we have experienced new types of maps which enable more interactivity, more dynamic changes and the incorporation of sound together with the visual presentation. Today thousands of small interactive cartographic products can be found on the Web around the world. However, compared to more traditional cartography, the evolution of small map applications on web are still in an early phase.


Electronic maps open for more animations and interactivity in the map itself. At the same time there are more possibilities for making closer connection between the map and the legend. Peterson (1999) introduces the term active legend for the use in interactive cartographic animations. In Peterson (1999) the legend works as a control panel for the map itself. Van den Worm (2001) discusses some more methods for the use of legends in small map applications and Midtbø (2003) gives others examples on the use of active legends. In a dynamic presentation of a thematic map, the symbols in the map may change during the animation and make it more difficult for the map reader use keep track of the information and compare it with the legend. This paper looks closer into methods for the active use of the legends on thematic maps. It shows how legends can split and moved around in the application to make it easier for the map reader to compare values in the legend with the symbols on the map. At the same time, operations in the map can be controlled by the legends. The paper also gives examples on how sound can be used to emphasize the connection between the legend and the thematic symbols on the map.


Midtbø, T (2003). Multivariable seeing maps trough interactive animations, Proceedings of the 21th International Cartographic Conference, 10-16 August 2003, Durban, South Africa.

van den Worm, J. (2001). Web map design in practice, in Kraak and Brown (eds.), Web Cartography, Taylor & Francis Inc. London, 2001.

Peterson, M.P. (1999). Active legends for interactive cartographic animation, International Journal of Geographical Information System, 13(4):375-383.