[mapserver-users] Refreshing AWS credentials for the /vsis3/ driver

[Peter Schmitt]

On Wed, Oct 26, 2016 at 1:39 PM, Even Rouault <even.rouault at spatialys.com>
wrote:

> I've written recently a best practice for generating cloud optimized
> geotiffs:
> https://trac.osgeo.org/gdal/wiki/CloudOptimizedGeoTIFF
> (it mentions deflate compression, but jpeg-compressed can work of course)
>
>
Thanks again, Even! I did some experimentation with a 19584x19584 file with
6 overview levels.  When the image is deflate-compressed:

> gdal_translate in.tif deflate.tif -co TILED=YES -co COMPRESS=DEFLATE -co
COPY_SRC_OVERVIEWS=YES

then this gdalinfo command does two range requests:

> env AWS_ACCESS_KEY_ID=foo
AWS_SECRET_ACCESS_KEY=bar CPL_VSIL_CURL_ALLOWED_EXTENSIONS=.tif
CPL_CURL_VERBOSE=YES
VSI_CACHE=TRUE gdalinfo /vsis3/pschmitt-test/deflate.tif 2>&1 | grep
"Content-Range:"
>  < Content-Range: bytes 0-49151/1038305419
>  < Content-Range: bytes 49152-147455/1038305419

When I jpeg-compress

> gdal_translate deflate.tif jpeg.tif -co TILED=YES -co COMPRESS=JPEG -co
PHOTOMETRIC=YCBCR -co COPY_SRC_OVERVIEWS=YES

then gdalinfo on the jpeg-compressed image does 13 range requests:

> env AWS_ACCESS_KEY_ID=foo
AWS_SECRET_ACCESS_KEY=bar CPL_VSIL_CURL_ALLOWED_EXTENSIONS=.tif
CPL_CURL_VERBOSE=YES
VSI_CACHE=TRUE gdalinfo /vsis3/pschmitt-test/jpeg.tif 2>&1 | grep
"Content-Range:"
> < Content-Range: bytes 0-49151/83731710
> < Content-Range: bytes 83656704-83705855/83731710
> < Content-Range: bytes 83722240-83731709/83731710
> < Content-Range: bytes 83705856-83722239/83731710
> < Content-Range: bytes 25231360-25280511/83731710
> < Content-Range: bytes 25165824-25214975/83731710
> < Content-Range: bytes 25214976-25231359/83731710
> < Content-Range: bytes 7602176-7651327/83731710
> < Content-Range: bytes 2228224-2310143/83731710
> < Content-Range: bytes 655360-704511/83731710
> < Content-Range: bytes 229376-278527/83731710
> < Content-Range: bytes 131072-180223/83731710
> < Content-Range: bytes 98304-131071/83731710

and 16 range requests if it also has an internal mask band.  It seems JPEG
compression greatly increases the size of the image metadata.

Cheers,
Pete
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