Summary
Cloud Optimized GeoTIFF (COG) is an official OGC Standard. The Open Geospatial Consortium (OGC) published version 1.0 in July 2023.
COG is based on GeoTIFF, which is, in turn, based on the TIFF format and is used as an interchange format for georeferenced raster imagery. COG is in wide use in NASA Earth Science data systems.
Version 1.0 is backward-compatible with the OGC GeoTIFF Standard of September 2019 as well as the original GeoTIFF 1.0 specification of 1995.
There are other scientific file formats that are well established within the NASA community, e.g., HDF5 and netCDF. However, there is continued interest and demand for the GeoTIFF file format, mostly as a distribution format for satellite or aerial photography imagery as well as for other kinds of data such as Digital Elevation Model (DEM) data and Digital Ortho Quadrangle data.
NASA ESDIS recommends the use of Cloud Optimized GeoTIFF (COG) for any data distribution that would be appropriate for a traditional GeoTIFF. COG files are fully backward compatible with all tools that are used in the reading of GeoTIFFs. Moving to using COG files allows those with access to cloud-based computing environments to have all the benefits of the expanded COG format without limiting those still using traditional tools.
Status
OGC Cloud Optimized GeoTIFF 1.0 is an approved data format standard for use in NASA Earth Science Data Systems (ESDS).
| ESCO RFC | ESDS-RFC-049 - Cloud Optimized GeoTIFF File Format |
| DOI | https://doi.org/10.5067/DOC/ESCO/ESDS-RFC-049v1 |
| Suggested Citation | Pollack, N. (2024). Cloud Optimized GeoTIFF (COG) File Format. NASA Earth Science Data and Information System Standards Coordination Office. https://doi.org/10.5067/DOC/ESCO/ESDS-RFC-049v1 |
| Specification | OGC Cloud Optimized GeoTIFF Standard |
| User Resources | ESDS-RFC-040. GeoTIFF File Format Cloud Optimized GeoTIFF. https://www.cogeo.org/ |
NASA Earth Science Community Recommendations for Use
Strengths
Cloud Optimized GeoTIFF (COG) is based on a previously approved NASA ESCO approved data format (GeoTIFF) and has been approved as an OGC data standard. COG files are backwards compatible with existing widely used standard data types while adding in new functionality required for efficient use of raster imagery in a cloud-based environment. Support is widespread and growing from standard geospatial software packages.
Weaknesses
Data supplier needs to be mindful of chunk size decisions as this can have an impact on access performance. Data requests that need access to multiple data chunks could see less than optimal performance.
Applicability
COG format is best suited to raster data, including satellite imagery. COG is well suited for data that is currently stored in GeoTIFF due to the simplest conversion.
Limitations
Not appropriate for non-raster formats, as COG is derived from the TIFF image format.