Nature: a colour comparison between Northern South Africa and Northern Australia

Abstract

During 1983 DSTO in Australia measured the reflectances of grass, trees and soil in northern Australia, using a custom-build spectroradiometer. During 2002 CSIR in South Africa performed similar measurements in northern South Africa, using a commercial spectroradiometer. The measurement areas in South Africa and Australia have the same kind of topography and maximum average temperatures. The largest difference is rainfall, where northern Australia experiences more tropical weather systems, with up to six times more rain than northern South Africa. This has a significant influence on the vegetation. The vegetation of the Australian measurement sites is predominantly classified as Eucalyptus, while the South African sites are classified as Bushveld, with much more diverse plant growth. All spectral data was referenced to a calibrated white standard, and for comparison purposes been converted to CIELAB notation. In this document he L*a*b* components were plotted on two sub-plots, the first representing the L*-values, the second showing the a*b*-values. The colour of the grass (winter) for both countries is close to each other, but the South African grass is much lighter than the Australian grass. The colour difference is between 7 and 15 dE units (a colour difference of one dE unit is just noticeable with the human eye). The colour of the trees for both countries is also very close to each other, the Australian trees being greener than the South African trees. The colour difference is between 3 and 6 dE units. The colour differences of the grass and trees could be contributed to the higher rainfall in Australia. The soil colour for both countries is also close to each other. The South African soil is more yellow than the soil in Australia. The soil has a colour difference of between 4 and 7 dE units. In general, the data shows the colours of natural elements in South Africa are lighter than those in Australia. The data also shows that the South African colours are more chromatic than those measured in Australia. Over and above the military application, this might find application in the remote sensing industry as well as the fashion– and interior decorating industry.