[gdal-dev] Q: on gdalwarp of ecw file

[Jan Hartmann]

Thanks Jukka, very informative. I'll start with jpeg compressed tiffs 
and will do additional tests next year. I'm on a Cloud environment 
nowadays, so it's easy to set up clean VMs for testing. Any suggestions 
for experiments with different raster formats would be very welcome.

Jan

On 12/18/2012 12:33 PM, Jukka Rahkonen wrote:
> Jan Hartmann <j.l.h.hartmann <at> uva.nl> writes:
>
>
>>      Hi Even, are there any
>>        benchmarks to compare (uncompressed) gtif with the three formats
>>        above? My production maps are always tiled to 2000*2000 pixels,
>>        all zoomlevels precomputed. Very efficient with uncompresssed
>>        gtif, but they take lots of space. How much slower are these
>>        formats?
>>        Jan
> Hi,
>
> Here are some 6 years old numbers from some Mapserver tests:
> http://permalink.gmane.org/gmane.comp.gis.mapserver.user/23540
>
> The speed feels now rather slow compared with the feeling I have from our recent
> services but differences may be alike. Or then they are not because drivers are
> not the same anymore and new hardware can suit better for one than for another.
>
> We are using aerial images mostly as JPEG compressed tiffs now but I have not
> bothered to do any timings lately. They save 90-95% of disk space, they are not
> much slower and users have not noticed the difference in quality so for us the
> choice was pretty easy.
>
> It is usually too simplified to say that some file format is slower that some
> other because there are so many other factors also in play. JPEG200O is an
> infamous example. It is a complicated file format and many software are very
> slow with big geospatial JPEG2000 images, but there are applications which can
> handle them very fast. Sluggish software does not necessarily mean that the
> format itself is slow. Six year old numbers 270/120/24 images per minute for
> tiff, ECW, and JPG2000 with Kakadu prove mainly that there must have been
> something wrong in how Kakadu and GDAL were working together at that time.
>
> You can get the best information about the real speed in your environment by
> making your own tests. Others will praise you later if you make controlled tests
> and publish the arrangement and results somewhere for future references.
> Unfortunately I do not remember myself how I did my own tests but I believe I
> was using FWTools 2.0.4 binaries.
>
>
>
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