Re: [Openexr-devel] Multi-layer multi-pass files

[Florian Kainz]

Hi Ton,

The 32-character limit on channel and attribute names is still in place.
we are just days away from our next OpenEXR release; channel names with
arbitrary length will have to wait until the version after that.
Increasing the maximum length of channel names does break backwards
compatibility.  We'll have to find some way to deal with this problem.

Currently there is no standard naming scheme for layers.  Would you like
to suggest one?

Florian



Ton Roosendaal wrote:
> Hi OpenEXR team,
>
> I'm wrapping up work for our next Blender release, which supports  
> multi-layer multi-pass rendering now. We will make use of openexr files  
> for writing/reading an entire set of layers/passes in a single file.
>
> In May this year I've noticed a bug in the channel naming, which didn't  
> suppport longer nested names than 32 characters in total. I didn't get  
> an answer to that, is this fixed?
>
> Other question; is there a naming standard for layers/passes in files?  
> Or, how can we make sure that such files open nicely in other  
> applications that support openexr?
>
> Thanks,
>
> -Ton-
>
> On 12 May, 2006, at 13:06, Ton Roosendaal wrote:
>
> > Hi,
> >
> > It looks like channel names in files are truncated to be 31 chars  
> > (plus trailing zero) maximum. That seems to be defined in ImfName.h.
> >
> > In Blender we make use of the features as described in  
> > ImfChannelList.h, for image files with many channels to group them  
> > into nested layers. Unfortunately the maximum of 32 chars seems to be  
> > for the total name, not for the individual nexted parts.
> >
> > For example; in Blender you can define per render command:
> > - Layers (geometry based, like foreground/background)
> >   - Passes (shading based, like per Lamp or Combined)
> >     - Channels (R,G,B,A or X,Y,Z, etc)
> >
> > I get errors reading back files with a channel named like:
> >
> > Characters_and_platform.Combined.R
> >
> > Which is just 34 characters...
> > So, is this limited naming behaviour as expected?
> >
> > Thanks,
> >
> > -Ton-
>
> ------------------------------------------------------------------------ --
> Ton Roosendaal  Blender Foundation address@hidden  http://www.blender.org
>
>
>
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