Raster data transformation for land change analyses: Combined impacts of reprojecting and rescaling categorical maps on landscape composition and configuration

TY - CONF

T1 - Raster data transformation for land change analyses

T2 - 9th International Symposium on Spatial Accuracy Assessment in Natural Resources and Environmental Sciences, Accuracy 2010

AU - Christman, Zachary

AU - Rogan, John

PY - 2010/1/1

Y1 - 2010/1/1

N2 - The use of raster-based categorical maps from multiple sources necessitates the transformation of the geometric characteristics to directly compare maps, such as in land change analyses. Through the operations of reprojecting maps to a new geographic reference framework and rescaling pixel values to a new size, distortions of map information are introduced that can affect both the proportion and arrangement of thematic classes across the landscape. Using a sample land cover dataset, images were reprojected and rescaled using three common raster-based transformation methods and one new vector-based method. Through an evaluation of changing class areas and landscape ecology metrics, results demonstrate that the values of more than a third of pixels in a categorical map may be affected by common reprojecting and rescaling methods. While relative class area was best preserved by a nearest-neighbour resampling method, the contiguity of thematic classes and the overall fragmentation of the landscape was lowest when using a vector-based reprojecting and resampling method. Results reinforce the need for careful attention to categorical data transformations in land change analyses.

AB - The use of raster-based categorical maps from multiple sources necessitates the transformation of the geometric characteristics to directly compare maps, such as in land change analyses. Through the operations of reprojecting maps to a new geographic reference framework and rescaling pixel values to a new size, distortions of map information are introduced that can affect both the proportion and arrangement of thematic classes across the landscape. Using a sample land cover dataset, images were reprojected and rescaled using three common raster-based transformation methods and one new vector-based method. Through an evaluation of changing class areas and landscape ecology metrics, results demonstrate that the values of more than a third of pixels in a categorical map may be affected by common reprojecting and rescaling methods. While relative class area was best preserved by a nearest-neighbour resampling method, the contiguity of thematic classes and the overall fragmentation of the landscape was lowest when using a vector-based reprojecting and resampling method. Results reinforce the need for careful attention to categorical data transformations in land change analyses.

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M3 - Paper

SP - 129

EP - 132

Y2 - 20 July 2010 through 23 July 2010

ER -