Cloud Optimized GeoTIFFs (COGs hereafter) are a special formulation of GeoTIFF files that take advantage of internal overivews as well as tiling (and various forms of compression).
In the case of WebODM, all GeoTIFFs will be generated as COGs because the 2D Map View uses the special attributes of COGs to enable rapid display and preview of the data generated by WebODM.
When are COGs appropriate?
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COGs are most appropriate when the GeoTIFF is going to be hosted online and/or accessed by a program which can take advantage of HTTP GetRange Requests and/or internal overviews and tiles.
Why would one use COGs?
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The COG structure (internal overviews and tiling) allows for rapid viewing of the data in programs which are capable of reading tiled data and overviews (most GIS software [QGIS etc]). This advantage holds true whether or not the file is hosted online and served via HTTP or whether it is stored locally.
With these features in place, a COG should display much more quickly in a given application than a more legacy formatted GeoTIFF with no overviews and striped structure.
The Layer Properties panel can show that there are in fact internal overviews. Keep in mind that not every GeoTIFF has internal overviews, but every COG must.
:alt:QGIS Layer Properties showing an on-disk file size of 8.78 MB
Note that the on-disk file size is 8.78 MB for the COG due to the presence of internal overviews when compared to the 6.30 MB of the non-COG GeoTIFF below.
`Learn to edit <https://github.com/opendronemap/docs#how-to-make-your-first-contribution>`_ and help improve `this page <https://github.com/OpenDroneMap/docs/blob/publish/source/arguments_edit/cog.rst>`_!
