Integrated Dual-Level Abstraction in large-scale land cover mapping

The need for contextual representation of complex local variation in geographical phenomena is growing for a variety of uses and map users. The purpose of this research is to explore the possibility of enhancing the thought and communication potential of conventional thematic maps by presenting environmental method is presented to structure geographical space, called Integrated Dual were categorized into a dual general and local detail scheme, and developed for land cover mapping using digital orthophoto data.; Map development work showed that representing within-class variation and boundary detail is possible with the use of solid-filled color area symbols and color-contrast boundaries. Also, a nested-hierarchical classification scheme was developed to coincide with the visual layering of map information using different amounts of color contrast. Yet, the coarse resolution of the display screen seriously limited the amount of detail that could be displayed. At the same time, source image interpretation produced map class polygons of small size and often complex shapes. These limiting factors served to eliminate many interesting and possibly useful types of symbols.; To assess the merits of these new hybrid maps for screen display, a user evaluation study was administered, consisting of a questionnaire and interviews. Research results show that within-class variation and boundary detail in the maps in readable and useful ways. The addition of structure allows for the inclusion of more detail while maintaining a measure of visual simplicity found in conventional thematic mapping. By conveying more information, the possibility exists for making more effective decisions and for having confidence in the decisions made. Yet, the cartographer's task of faithfully representing the distribution of geographic phenomena is not only more difficult, but is also more important because of the possible misinterpretations made by map users. At the same time, the map user must become more sophisticated if the design potential of these hybrid maps is to be fully appreciated.