top of page
GeoWGS84AI_Logo_edited.jpg

MrSID vs COG: A Technical Comparison for Advanced GIS Users

Effective raster data transport and storage are essential in the geospatial sector. Technical procedures frequently encounter two formats: COG (Cloud Optimized GeoTIFF) and MrSID (Multiresolution Seamless Image Database). Large geographic rasters are managed by both, although there are notable differences in their structures, performance traits, and ecosystem support. To assist advanced GIS users in selecting the format most suitable for specific use scenarios, this article provides a comprehensive technical comparison.


MrSID vs COG
MrSID vs COG (Generated by Google Gemini)

  1. Format Overview


MrSID


  • Developer: LizardTech

  • Type: Proprietary, wavelet-compressed raster format

  • Key Feature: Multiresolution storage designed for quick zooming and panning across varying levels of detail

  • Compression: Lossy or lossless (though often regularly lossy), typically at a 20:1 ratio without visible quality drop

  • Use: Large volumes of aerial photography, scanned maps, and government archives.


COG (Cloud Optimized GeoTIFF)


  • Developer: Open format, standard developed by the geospatial open-source community

  • Type: GeoTIFF with internal tiling and overviews designed for HTTP range requests

  • Key Feature: Cloud object storage, native and streaming access

  • Compression: TIFF-compatible compression (DEFLATE, LZW, JPEG, ZSTD, WEBP)

  • Use Cases: Cloud-based GIS workflows, web mapping services, open data portal


  1. Data Access and Performance


MrSID


  • Keeps images in a pyramidal wavelet format and retrieves them at any resolution quickly.

  • Highly optimized for desktop GIS, very low latency when zooming in and out, and panning.

  • Must access via proprietary SDKs or licensed plug-ins for full functionality and decoding.

  • Streaming is facilitated via MrSID Mosaic Express or other similar server solutions.


COG


  • Developed to be used with stateless HTTP range requests, making it a cloud-native solution.

  • Fully compatible with S3, GCS, Azure Blob, or any object store.

  • Raster readers (GDAL, Rasterio) only request the tiles/overviews that they need to minimize I/O.

  • Designed for the best performance in distributed multi-user environments and web applications.


  1. Compression and Storage Efficiency


MrSID:


  • Wavelet compression provides high compression ratios (around 20:1 is highly typical).

  • Best suited for archiving where size is of utmost importance.

  • A proprietary compression algorithm, therefore a licensed encoder, is required.


COG:


  • Options for potentially lossy (JPEG) or lossless (LZW crispness and ZSTD speed) compression are available.

  • File sizes are somewhat larger than MrSID at a comparable visual quality.

  • Does not sacrifice transparency and interoperability between platforms.


  1. Ecosystem and Interoperability


MrSID:


  • Supported by leading desktop GIS platforms (ArcGIS, QGIS with plugin).

  • Limited support in web-based or FOSS environments.

  • Requires licensed software (GeoExpress) to encode.


COG:


  • Strongly supported by the FOSS ecosystem (GDAL, QGIS, Rasterio).

  • Easily consumable by cloud-native geospatial stacks (Terrascope, STAC, Earth Engine).

  • Increasingly embraced by governments and open data publishers (NASA, USGS).


  1. Security and Longevity


  • MrSID: Exclusive—reliant on Extensis for ongoing assistance. Vendor lock-in risk.


  • COG: Open specification—widely used, transparent, and driven by the community. Long-term data stewardship that is future-proof.


  1. When to Use Which?


Select MrSID if


  • Large archives require extremely high compression ratios.

  • MrSID-encoded legacy data is essential to your workflows.

  • You mostly use licensed software in desktop GIS setups.


Select COG if


  • Cloud-native streaming performance is what you're looking for.

  • Long-term interoperability and open standards are important to you.

  • You use distributed access, web services, or APIs in your workflows.


MrSID remains a strong choice for organizations with sizable, compressed raster archives and a traditional desktop GIS workflow. However, the geospatial space is quickly shifting to open, cloud-native formats, making COG the common format of choice for modern distributed, scalable GIS applications.


For advanced GIS users, the choice is simply a question of preservation vs. accessibility:


  • If preservation and supporting legacy formats are paramount → use MrSID.

  • If scaling up, interoperability, and performance in the cloud are paramount → use COG.


For more information or any questions regarding the MrSID and COG, please don't hesitate to contact us at


USA (HQ): (720) 702–4849


(A GeoWGS84 Corp Company)

 
 
 

Comments

bottom of page