Geographic Information Systems
Data Quality Issues

Mark Foley
mark.foley@dit.ie

Data Quality Issues

Accuracy versus precision

Accuracy versus precision

Resolution and generalization of raster datasets

Resolution and generalization of raster datasets

Scale-related generalization

Scale-related generalization

Sources of Error

Conceptual view of uncertainty

Conceptual view of uncertainty

Two mental maps of the location of Northallerton in the UK

Two mental maps of the location of Northallerton in the UK

Multiple representations of Tryfan, North Wales

Multiple representations of Tryfan, North Wales

Multiple representations of Tryfan, North Wales

Multiple representations of Tryfan, North Wales

Problems with remotely sensed imagery: (left) example of a satellite image with cloud cover (A), shadows from topography (B), and shadows from cloud cover (C); (right) an urban area showing a building leaning away from the camera

Problems with remotely sensed imagery: (left) example of a satellite image with cloud cover (A), shadows from topography (B), and shadows from cloud cover (C); (right) an urban area showing a building leaning away from the camera

Land use change detection using remotely sensed imagery

Land use change detection using remotely sensed imagery

Digitizing errors

Digitizing errors

Topological errors in vector GIS: (a) effects of tolerances on topological cleaning and (b) topological ambiguities in raster to vector conversion

Topological errors in vector GIS: (a) effects of tolerances on topological cleaning and (b) topological ambiguities in raster to vector conversion

Vector to raster classification error

Vector to raster classification error

Topological errors in vector GIS: (a) loss of connectivity and creation of false connectivity and (b) loss of information

Topological errors in vector GIS: (a) loss of connectivity and creation of false connectivity and (b) loss of information

Effect of grid orientation and origin on rasterization

Effect of grid orientation and origin on rasterization

Generation of sliver polygons

Generation of sliver polygons

Finding and modelling errors in GIS

Point-in-polygon categories of containment

Point-in-polygon categories of containment

Simulating effects of DEM error and algorithm uncertainty on derived stream networks

Simulating effects of DEM error and algorithm uncertainty on derived stream networks

Simulating the effects of DEM error and algorithm uncertainty on radio communications in the Happy Valley area

Simulating the effects of DEM error and algorithm uncertainty on radio communications in the Happy Valley area

Simulating uncertainty in the siting of nuclear waste facilities

Simulating uncertainty in the siting of nuclear waste facilities

Bootstrapping or ‘leave one out’ analysis

Bootstrapping or ‘leave one out’ analysis

Managing error