All exrs are zip1 scanline. We created the multichannels in nuke from zip1
vray renders.
On Sep 1, 2011 8:41 PM, "Deke Kincaid" <[email protected]> wrote:
> Sorry, no benchmarks yet. I started making a doc about exr to put up on
> nukepedia that one day I will finish.
>
> Ryan: are the exr files scanline or tile exr's?
>
> -deke
>
>
> On Thu, Sep 1, 2011 at 14:18, Dan Walker <[email protected]> wrote:
>
>> Hey Deke,
>>
>> Could you elaborate on the last paragraph. Given a multi chan EXR. Are
>> there bench mark tests that have been done to track optimal setups in
comps?
>> Basically, better to do this than that. I know there are a multitude of
>> scenarios you have to consider but there are some tips users can supply
>> based on their experiences.
>>
>> I'd say submitting them in an email thread is probably the best approach
or
>> the Foundry can compile and validate the submitted tips. They're not busy
>> working on anything at the moment, right?! ;-)
>>
>>
>>
>>
>> On Thu, Sep 1, 2011 at 1:55 PM, Deke Kincaid <[email protected]
>wrote:
>>
>>> Exr files are interleaved. So when you look at some scanlines, you need
>>> to read in every single channel in the EXR from those scanlines even if
you
>>> only need one of them. So if you have a multichannel file with 40
channels
>>> but you only use rgba and one or two matte channels, then your going to
>>> incur a large hit.
>>>
>>> Another thing is it sounds like you are shuffling out the channels to
the
>>> rgb before you merge them. This also does quite a hit in speed. It is
far
>>> faster to merge and pick the channels you need rather then shuffling
them
>>> out first.
>>>
>>> -deke
>>>
>>> On Thu, Sep 1, 2011 at 12:37, Ryan O'Phelan <[email protected]
>wrote:
>>>
>>>> Recently I've been trying to evaluate the load of nuke renders on our
>>>> file server, and ran a few tests comparing multichannel vs.
non-multichannel
>>>> reads, and my initial test results were opposite of what I was
expecting.
>>>> My tests showed that multichannel comps rendered about 20-25% slower,
and
>>>> made about 25% more load on the server in terms of disk reads. I was
>>>> expecting the opposite, since there are fewer files being called with
>>>> multichannel reads.
>>>>
>>>> For what it's worth, all reads were zip1 compressed EXRs and I tested
>>>> real comps, as well as extremely simplified comps where the
multichannel
>>>> files were branched and then fed into a contact sheet. I was monitoring
>>>> performance using the performance monitor on the file server using only
20
>>>> nodes and with almost nobody using the server.
>>>>
>>>> Can anyone explain this? Or am I wrong and need to redo these tests?
>>>>
>>>> Thanks,
>>>> Ryan
>>>>
>>>>
>>>>
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>>>
>>>
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>>
>>
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