Development of a system for rapid topographic map revision of urban built-up areas

Abstract

A “hybrid”, high throughput image processing system is described to provide updated urban information on Canadian topographic maps from moderate resolution image sources such as SPOT. Two features are of particular interest; Buildings to Scale (BTS) (i.e., large buildings to be represented by individual symbols), and Built-up Areas (BUA), the majority of urban developed encompassing smaller structures (typically residential areas) that are represented on maps in a generalized way by a shading or tint. This paper addresses mapping of the latter, hereafter referred to as BUA mapping. A data-driven approach that utilizes a linear vegetation index to reduce data dimensionality and facilitate automation was developed. Full scene interpretation can be completed in approximately 2–3 minutes even on low-cost desktop computers. Accuracy of the BUA mapping output is comparable with that previously provided through traditional labour-intensive means (i.e., visual interpretation of aerial photography). Our process also provides a mapping of high intensity urban areas such as industrial parks and urban cores, thus providing search areas for subsequent extraction of large buildings. Finally, it is argued that the automated techniques described here have applicability in international urban mapping initiatives and the methodology can be adapted to the mapping of natural features such as water bodies and forests.