![]() This is ok if you want to download all the bands at once, like in an aerial photo. $ gdal_translate ori.tiff out.tiff -co COMPRESS=LZW -co TILED=YES ![]() The first compresses more but is less compatible with some libraries. This is, that instead of writing all the row, the image is divided in small tiles, so only some of them are downloaded. The basic thing to understand is that the GeoTIFF must be tiled. Create a COG using GDAL from the command line If the GeoTIFF data is created from a script using GDAL, it is also possible to do it inside using python or any language with the GDAL bindings.īut, before trying to convert anything, better check if the file is already in a good format and if you prefer using overviews or not. The easiest way to create a COG is using the GDAL command line interface. LZW is accepted more easily than DEFLATE, but the later compresses more There are two important parameters to set which aren't in the standard Optional: tile content of first overview level Optional: tile content of last overview level Optional: IFD (Image File Directory) of last overview (typically subsampled by a factor of 2N), followed by the values of its tags that don't fit inline Optional: IFD (Image File Directory) of second overview (typically subsampled by a factor of 4), followed by the values of its tags that don't fit inline Optional: IFD (Image File Directory) of first overview (typically subsampled by a factor of 2), followed by the values of its tags that don't fit inline Values of TIFF tags that don't fit inline in the IFD directory, such as TileOffsets?, TileByteCounts? and GeoTIFF keys IFD (Image File Directory) of full resolution image When a file os properly organized, the HTTP GET range request ("bytes: start_offset-end_offset" HTTP header) can be used, and only the parts needed are downloaded.Īs Even Rouault explains in the GDAL COG page, the structure is: Create a COG using GDAL from the command lineĬloud Optimized GeoTIFFs, as explained in the previous section, are organized to be downloaded by parts.In this short tutorial, you can find how to create them, and how to read them from a browser or the command line. It does this by leveraging the ability of clients issuing HTTP GET range requests to ask for just the parts of a file they need. Or, better defined in the COG web site:Ī Cloud Optimized GeoTIFF (COG) is a regular GeoTIFF file, aimed at being hosted on a HTTP file server, with an internal organization that enables more efficient workflows on the cloud. Cloud Optimized GeoTIFF (COG) is simply an intelligent way to store a GeoTIFF file.
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