mural mural on the wall

The ‘Pan American Unity Mural’ by Diego Rivera is on display at SF MOMA while its permanent home at the City College of San Francisco is under renovation. The Diego Rivera Mural Project archives the history, process photos, letters, notes and other information about the mural.

As part of the temporary move and physical restoration, the conservators underwent a comprehensive virtual preservation project, which included capturing both the color and the 3d surface shape (called a Digital Elevation Model). The entire image can be explored through a web based viewer… it gets super close, and still is only 1/16th the full resolution. One full res panel is available for exploration here.

Each of these 2D images is 163,861 pixels long and 49,177 pixels high or 8.06 billion pixels (8.06-gigapixels) in total. On the mural, the tiny square area each of these pixels represent is 0.139mm in length: for context, a thick human hair is .100 mm wide. This means that every square millimeter of the 6.7 meter by 22.5 meter (22’ by 74’) mural is covered by 51.75 pixels. These, have the resolution and precision to show the shape of an individual bristle stroke of Rivera’s paint brush and the path it took through the fresco’s wet plaster. Additionally, condition issues, such as cracks in the surface are also clearly visible in the 3D data. “2D Color and Shape from 3D data” https://exhibits.stanford.edu/rivera/feature/2d-color-and-shape-from-3d-data

This detailed documentation has led to the identification of the boundaries of each section of daily work, as well as mapping the condition of the mural and identifying areas that may require preservation and repair.