Approaches to Delineating Built-Up Areas Using Road Network Data

What is it about?

Delineated built-up areas may be used for applications such as navigation, database enrichment and the identification of urban sprawls. As more road network data have become available, many studies have considered using road network data to delineate built-up areas. This study investigated the three existing approaches to delineating built-up areas on a map: the grid-based approach, kernel density analysis and an approach based on street blocks. These approaches are evaluated and compared from three angles. First, two measures were proposed to quantitatively evaluate the land area of the delineated built-up areas; second, a questionnaire was designed to visually compare the representations of the delineated built-up areas; and, third, the time complexity of using each approach was tested. The three approaches were applied to different sets of road network data for New Zealand; data from buildings and residential areas were used as benchmarks. The results showed that: (1) in a quantitative assessment, both the grid-based approach and kernel density analysis can usually detect more built-up areas than the approach based on street blocks; (2) on visual inspection, most of the students who completed the questionnaire performed the representations using the approach based on street blocks; and (3) in time complexity, the approach based on street blocks always takes the least time.

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Why is it important?

The results showed that: (1) in a quantitative assessment, both the grid-based approach and kernel density analysis can usually detect more built-up areas than the approach based on street blocks; (2) on visual inspection, most of the students who completed the questionnaire performed the representations using the approach based on street blocks; and (3) in time complexity, the approach based on street blocks always takes the least time.

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