These text protos contain composite JPEG/PNG images^[1] representing the EGM2008 Earth Gravitational Model[^2] published by the National Geospatial-Intelligence Agency.[^3]

[^1] Julian, Brian, and Angermann, Michael. “Resource efficient and accurate altitude conversion to Mean Sea Level.” To appear in 2023 IEEE/ION Position, Location and Navigation Symposium (PLANS).

[^2]: Pavlis, Nikolaos K., et al. “The development and evaluation of the Earth Gravitational Model 2008 (EGM2008).” Journal of geophysical research: solid earth 117.B4 (2012).

[^3]: National Geospatial-Intelligence Agency. “Office of Geomatics.” 2022. URL: https://earth-info.nga.mil.