[Sidefx-houdini-list] bgeo.gz and gzip with windows

Chris AtLee catlee at sidefx.com
Thu Jun 19 10:26:08 EDT 2008


Pablo Giménez wrote:
> 2008/6/17 Nicholas Pliatsikas <nick_p102 at hotmail.com>:
> 
>> Does anyone know the full benefits of using bgeo.gz? I.e I know the files
>> sizes are smaller, meaning less network traffic and uses less space on our
>> servers. But would complex setups with geos writing in houdini or delayed
>> read archives rendering through mantra require more time to process?
>> Just so we can access if its worth looking into this further at the moment.
>> Cheers
>> Nicholas Pliatsikas
> 
> Yes, if you are dealing with big geometry files using gz is really good, but
> in my experience bzip2 is really good, I have seen ratios very clos to 1:8
> in the size, bgeo is binary so bzip2 works much better on this kind of
> files.
> I think there is a version of bzip2  for windows.
> The only problem I have experienced using compressed files is rendering from
> file, but this was on version 8, I don´t know if this have been solved in
> version 9.

LZMA is also an option.  It performs significantly better than bz2, and
is also faster to decompress than bz2.

I ran a test against about 7000 bgeo files here, here's a summary of my
results:

Compression Method      gzip     bzip2     lzma
Average Compression
  (% of original size)  45.74    47.78     34.76
Best compression ratio
  (% of original size)   7.22     4.50      2.20
Worst compression ratio
  (% of original size) 136.00   137.14     93.50
Standard Deviation       0.18     0.23      0.17

So, for the files that I was testing, bz2 is in fact not a good choice
to use.  It performs worse on average than gzip and has more varied
behaviour.  lzma is a clear winner here.  I didn't measure the
compression times for the different methods here, but other reports
online indicate that lzma is slower than gzip, but faster than bz2.

I know lzma is available for Linux, and it looks like the LZMA SDK
includes lzma.exe for Windows, but I haven't tested it.

Cheers,
Chris



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