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From Marshall Schor <...@schor.com>
Subject Re: big offsets efficiency, and multiple offsets
Date Wed, 04 Dec 2013 19:16:44 GMT
Echoing Richard,

1) It would perhaps make more sense to be more direct about each of the
different types of data.  UIMA "built-in" only the most "popular" things - and
Annotation was one of them.

Annotation derives from Annotation-base, which just defines an associated Sofa /
view.

So it would make more sense to define different kinds of highest-level
abstractions for your project, related to the different kinds of views/sofas. 
Audio might entail a begin / end style of offsets;  Images might entail a pair
x-y coordinates, to describe a (square) subset of an image.  Video might do
something like audio, or something more complex...

UIMA's use of the AnnotationBase includes insuring that when you add-to-indexes
(an operation that implicitly takes a "view" - and adds a FS to that view), that
if the FS is a subtype of AnnotationBase, then the FS must be indexed in the
associated view to which that FS "belongs"; if you try to add-to-index in a view
other than the one the FS was created in, you get this kind of error:

Error - the Annotation "{0}" is over view "{1}" and cannot be added to indexes
associated with the different view "{2}".

The logic behind this restriction is:  an Annotation (or, more generally, an
object having a supertype of AnnotationBase) is (by definition) associated with
a particular Sofa/View,  and it is more likely that it is an error if that
annotation is indexed with a sofa it doesn't belong with.

Of course, Feature Structures which are not Annotations (or more generally, not
derived from AnnotationBase), can be indexed in multiple views.

2) By keeping separate notions for pointers-into-the-Sofa, you can define
algorithmic mappings for these that make the best sense for your project,
including notions of fuzzyness, time-shift (imagine the audio is out-of-sync
with the video, like lots of u-tube things seem to be), etc.

-Marshall


On 12/4/2013 9:31 AM, Jens Grivolla wrote:
> Hi, we're now starting the EUMSSI project, which deals with integrating
> annotation layers coming from audio, video and text analysis.
>
> We're thinking to base it all on UIMA, having different views with separate
> audio, video, transcribed text, etc. sofas.  In order to align the different
> views we need to have a common offset specification that allows us to map e.g.
> character offsets to the corresponding timestamps.
>
> In order to avoid float timestamps (which would mean we can't derive from
> Annotation) I was thinking of using audio/video frames with e.g. 100 or 1000
> frames/second.  Annotation has begin and end defined as signed 32 bit ints,
> leaving sufficient room for very long documents even at 1000 fps, so I don't
> think we're going to run into any limits there.  Is there anything that could
> become problematic when working with offsets that are probably quite a bit
> larger than what is typically found with character offsets?
>
> Also, can I have several indexes on the same annotations in order to work with
> character offsets for text analysis, but then efficiently query for
> overlapping annotations from other views based on frame offsets?
>
> Btw, if you're interested in the project we have a writeup (condensed from the
> project proposal) here:
> https://dl.dropboxusercontent.com/u/4169273/UIMA_EUMSSI.pdf and there will
> hopefully soon be some content on http://eumssi.eu/
>
> Thanks,
> Jens
>
>


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