Re: Using oa:SpecificResource with oa:hasTarget

On Jul 6, 2012, at 10:00 AM, Paolo Ciccarese <paolo.ciccarese@gmail.com> wrote:

> Jim,
> 
> On Fri, Jul 6, 2012 at 9:32 AM, James Smith <jgsmith@gmail.com> wrote:
> So I would construct the target by starting with the most general resource to which the annotation could apply and then scoping down until we have the part of the resource the annotation is targeting. If we want to target a rectangular region of an image, then the target URI would address the full image and a fragment selector could use the 'xywh=...' form to select the area within that image.
> 
> Referring to figure 5.2 in this section http://www.openannotation.org/spec/core/#SelectorFragment 
> are you confirming the use of a URN for the SpTarget1, the full image URL as Target1 and the selection details as part of Selector1?


I think so. Given something like the following (figure 5.2.1):

<Anno1> a oa:Annotation ;
  oa:hasBody <Body1> ;
  oa:hasTarget <SpTarget1> .

<SpTarget1> a oaSpecificResource ;
  oa:hasSelector <Selector1> ;
  oa:hasSource <Target1> .

<Selector1> a oa:FragmentSelector ;
  rdf:value "fragment1" .

I would let SpTarget1 and Selector1 be the equivalent of blank nodes, Target1 would be the URL of the image being annotated, and fragment1 would be the "xywh=..." piece showing which part of the image is being annotated.

With streaming video, we're doing something similar except that the selector is compound, selecting time into the video using a fragment selector and selecting the area within the frames with a SVG selector (we're allowing non-rectangular selections). Target1 is the nominal URL of the video (nominal because the HTML5 video element doesn't have a way to specify the name of the resource being shown - only a way to name the various resources that provide representations of the user-perceived resource being shown - so we require an additional data- attribute on the video element to tell us the URL we're targeting).

I could see a need for additional information to be able to recreate the annotation. Again, with streaming video, we're adding exif:height and exif:width attributes to the SVG selector so we know how big the play surface is for the annotation since this isn't a constant attribute of the video. But this additional information is hanging from the general structure outlined above based on figure 5.2.1.

-- Jim