Cultural Heritage Imaging

Since 2002, CHI has fostered the scientific digital capture and documentation of the world’s cultural, historic, and artistic treasures. Focusing on methods of computational photography, CHI offers technologies, tools, hands-on training, consulting and imaging services to those who care for the objects and sites of our shared human legacy. As a 501(c)(3) nonprofit, CHI’s vision is to democratize scientific imaging technology, empowering people all over the world to document their own cultural heritage in a way that preserves and protects it for future generations.

The Imaging Team

Marlin Lum, Mark Mudge, and Carla Schroer, the CHI imaging team, planned and performed the imaging and are responsible for building the 3D and 2D documentation from the data. They could not have undertaken this project without the leadership and help of Will Maynez.

Mark Mudge(left) and Will Maynez at the mural in 2019. Photo: Marlin Lum
Carla Schroer. Photo: Marlin Lum
Marlin Lum. Photo: Marlin Lum

A multi-year collaborative project with many people to thank


Will Maynez, historian and steward of the mural at City College, supported this work in a variety of ways, including clearing all the hurdles to get access to the mural and supporting the CHI team on site during image capture. Visit the CCSF sponsored website where Will has gathered his knowledge and insights about the mural: riveramural.org.

Many others on the CCSF campus supported and encouraged the project.

Thanks to the special SFMOMA sponsored conservation team who developed the information for the giornata and condition maps. This includes the lead conservator for the project Kiernan Graves of Site & Studio Conservation, along with Anne Rosenthal, Andrea Gregorini, Teal Patterson, Abigail Porter, and Camilla Martinucci. Michelle Barger, SFMOMA Head of Conservation, strongly supported this imaging project. Additional conservators and engineers from UNAM in Mexico, along with Italian conservators were involved in the SFMOMA mural conservation effort. The primary work to do the detailed condition assessment and giornata maps occurred in the summer of 2019. The conservation team was heavily involved in the planning and protection of the mural surface during the move to SFMOMA in spring 2021.

Stanford Libraries provided extensive assistance during the preparation of the site and presentation of the mural documentation. Ben Albritton, Rare Books Curator and project lead from the libraries, put in enormous effort to resolve technical and other issues, on top of his regular day job. We are grateful.

We also wish to thank the following Stanford Libraries colleagues for their time, advice, and assistance: Cathy Aster, Chris Beer, Andrew Berger, Tony Calavano, Hannah Frost, Gary Geisler, Adan Griego, M.A. Matienzo, Roberto Trujillo.

Special mention of thanks to Jon Stroop at Princeton Libraries for advice on management of very large image files in a IIIF environment.

Additional Technical Support

Tom Noble and Neffra Matthews of the US Bureau of Land Management National Operations Center, provided photogrammetry expertise to the CHI team. In addition to being our long time photogrammetry mentors, they provided specific advice for this project.

Charles Walbridge and Dan Dennehy of the Minneapolis Institute of Art donated both computer processing and human time to the project. Charles’ willingness to apply MIA’s large server to complete the processing work we couldn’t do on our machines, was an enormous help.

Robert Kastler of the Museum of Modern Art provided color management advice before and after the original image collection in 2015.

Erik Landsberg of Cultural Heritage Digitization Consulting provided color management advice and profiled the Canon 5DSR camera used in the imaging.

Taylor Bennett also provided computer processing resources to the project, in the form of a long term loan of a computer powerful enough to perform much of the processing.


Friends of the Diego Rivera Murals, a San Francisco Bay Area group of people devoted to protecting the mural and restoring it to prominence, provided major funding for the 2015 and 2017 imaging work. Nylda Gemple and the late Herb Gemple convened the group in 2006. Funding was managed by the CCSF Foundation through the Diego Rivera Account.

The 2020 imaging project was funded by a grant from the National Endowment for the Humanities: Bringing Diego Rivera’s 1940 ‘Pan American Unity’ Mural to the People, Virtually! Grant Number: PB-274476-20.

Any views, findings, conclusions, or recommendations expressed in this online exhibition, do not necessarily represent those of the National Endowment for the Humanities.

Additional funding was provided by the City College of San Francisco Foundation, Diego Rivera Account, and CHI’s wonderful donors.

Notes About the Images

The full resolution of the orthomosaic (color) and Digital Elevation Model (DEM) (shape) is 163,864 pixels across by 49,177 pixels tall totaling 8.06 billion pixels or 8.06 gigapixels. You can learn more about how photogrammetry was used to create the shape and color maps on the feature page 2D Color and Shape from 3D Data.

It has proven a challenge to deliver such large images on Stanford Library's current infrastructure. We have made a temporary compromise between offering the rich detail captured by the full resolution images and what can be feasibly delivered in the user interface at this time. We hope to be able to make the full resolution images of the entire mural viewable here in the future.

All Images, graphics, and videos used in this exhibit were created by Cultural Heritage Imaging except where noted. Cultural Heritage Imaging is the copyright holder for these materials. With the exception of the high resolution color and shape maps, these materials are available under a Creative Commons license - as marked in the videos themselves and in the metadata for the images and graphics. These items can be shared for non-commercial use with attribution to Cultural Heritage Imaging per the (CC-BY-NC-ND 4.0) license.

The giornata map and the condition map are courtesy of SFMOMA with special thanks to Site & Studio Conservation.

The historic photos are from the Works Progress Administration (WPA) archive.

Embedded links to some historic materials found on The Mural in San Francisco page have the rights noted by the host institutions for those materials.

The mural artwork is in copyright (see below), and therefore, the large orthomosaics are not available for download and reuse without express permission.

Diego Rivera, The Marriage of the Artistic Expression of the North and of the South on This Continent, also known as Pan American Unity, 1940; courtesy City College of San Francisco; © Banco de México Diego Rivera and Frida Kahlo Museums Trust, Mexico City / Artists Rights Society (ARS), New York.