Examination of the positional accuracy of linear features  

Authors / CoAuthors

Lawford, G.J.

Abstract

Although the positional accuracy of spatial data has long been of fundamental importance in GIS, it is still largely unknown for linear features. As early as 1987 the US National Center for Geographic Information and Analysis identified accuracy as one of the key elements of successful GIS implementation. Yet two decades later, while there is a large body of geodetic literature addressing the positional accuracy of point features, there is little research addressing the positional accuracy of linear features, and still no accepted accuracy model for linear features. This research aims to address some of these shortcomings by exploring the effect on linear feature positional accuracy of feature type, complexity, segment length, vertex proximity and 'scale'. A geographically sensible error model for linear features using point matching from a test line to a reference line of higher accuracy is developed and a case study undertaken using well-regarded and commonly used Australian topographic datasets. Half a million points are matched between test and reference lines for a range of topographic feature types at a spectrum of 'scales' and summary statistics are generated that shed light on the relationships between positional accuracy and 'scale', feature type, complexity, segment length, and vertex proximity. It is found that (a) metadata for the tested datasets significantly underestimates the positional accuracy of the data; (b) positional accuracy varies with 'scale' but not, as might be expected, in a linear fashion; (c) positional accuracy varies with feature type, but not as the rules of generalisation suggest; (d) complex features lose accuracy faster than less complex features as 'scale' is reduced; (e) the more complex a real-world feature, the worse its positional accuracy when mapped; and (f) accuracy mid-segment is poorer than accuracy end-segment.

Product Type

nonGeographicDataset

eCat Id

67272

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Keywords

• External PublicationScientific Journal Paper

( Theme )

• topography

( Theme )

• mapping

( Theme )

• GIS

( Theme )

• data

Australian and New Zealand Standard Research Classification (ANZSRC)

• Earth Sciences

• Published_Internal

Publication Date

2008-08-01T00:00:00

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Australian Government Security ClassificationSystem    

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Creative Commons Attribution 4.0 International Licence    

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geoscientificInformation

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