Invalid Data is a new project, part of my ongoing collaboration with the Digital Earth Australia platform and Geoscience Australia. This project involves a critical engagement with the cloud-filtering algorithms employed by Geoscience Australia’s “Digital Earth Australia” (DEA) platform.
Geoscience Australia developed DEA as a “data cube” which stacks 40 years of Australian satellite data into a database form that is accessible using a range of GIS applications and programming environments.
Scientists at DEA use satellite data to track environmental change over time, assessing vegetation health and the presence of water on the land. In order to track these changes however, they must filter clouds and cloud shadow from the data in order to obtain a clear picture of the land, and they employ complex algorithms to identify and excise this atmospheric noise. The result of this filtering is a huge and constantly growing archive of “invalid data” – which is in fact a multi-year record of the incredible cloud formations that daily spread across the continent.
Production of these images involved working creatively with the structures and capacities of the DEA platform, and in particular, with the Fmask and ACCA algorithms used in DEA to mask clouds and cloud shadow. These images invert normal geoscientific process, filtering out the land and focusing on the cloud data that is usually filtered from the archive. In choosing to focus on the clouds and algorithmically filter everything else, this project inverts the figure/ground relationship employed in satellite imaging, bringing what is normally deemed redundant into focus.