cog

Create Cloud-Optimized GeoTIFFs instead of normal GeoTIFFs. Default: False

Parameter Type:

Boolean

Parameter Domain:

True: --cog

False: null

Parameter Default:

False: null

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Resource	Impact
CPU	●●○ | Medium
GPU	○○○ | None
HDD	●●○ | Medium
RAM	●●○ | Medium
Time	●●○ | Medium

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What Are Cloud Optimized GeoTIFFs (COGs)?

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?

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?

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.

Example Images

True: --cog

The Raster Information tool in QGIS can print information from gdalinfo which can be used to confirm the conformance of a GeoTIFF to the COG spec.

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.

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.

False: null

The Raster Information tool in QGIS does not show LAYOUT=COG, which indicates that this GeoTIFF does not meet the COG spec.

The Layer Properties panel shows that the GeoTIFF lacks all levels of Internal Pyramids.

Note that the on-disk file size is 6.30 MB for the COG due to the lack of internal overviews when compared to the 8.78 MB of the COG GeoTIFF above.

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