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Re: Expressing complex regions with media fragments - use cases + possible solution

From: Bernhard Haslhofer <bernhard.haslhofer@univie.ac.at>
Date: Fri, 10 Sep 2010 08:50:51 +0200
Cc: raphael.troncy@eurecom.fr, Davy Van Deursen <davy.vandeursen@ugent.be>, Jack Jansen <Jack.Jansen@cwi.nl>, public-media-fragment@w3.org, Robert Sanderson <azaroth42@gmail.com>, Simon Rainer <Rainer.Simon@ait.ac.at>
Message-Id: <CDE66659-0733-4576-A6C4-D6C1DE58536F@univie.ac.at>
To: Silvia Pfeiffer <silviapfeiffer1@gmail.com>

for images  we can definitely solve the rendering with SVG; for other media types (e.g., videos) we could also define / reuse elements that define the necessary semantics for expressing segment/fragment/region information. But then we have two divergent developments: "the MF spec for addressing fragments in media objects " (implemented by browsers) and  some other "spec for addressing fragments in media objects in the context of Web annotations" (implemented by annotation clients running in browsers).

If the MF spec proposes some solution (ref approach, SVG approach, whatever) for addressing complex regions, we could build on that...


On Sep 9, 2010, at 3:13 PM, Silvia Pfeiffer wrote:

> 2010/9/9 RaphaŽl Troncy <raphael.troncy@cwi.nl>
> Hi Silvia,
> I'd go as far as saying that if it is possible to write the
> specification of the region highlight in a document rather than in a url
> as Bernhard has done in his examples, there isn't a need for reference
> URLs and the svg-fragment example is perfectly fine. Just use SVG filters:
> <?xml version="1.0" ?>
> <r:RDF xmlns:r="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
>       xmlns:a="http://www.w3.org/2000/10/annotation-ns#"
>       xmlns:d="http://purl.org/dc/elements/1.1/">
> <r:Description>
> <a:annotates r:resource="http://serv1.example.com/some/page.html"/>
> <x:svg-fragment rdf:parseType="Literal">
> <svg:defs xmlns:svg="http://www.w3.org/2000/svg">
> <svg:filter id="c1">
> <svg:symbol id="Polygon" xmlns:svg="http://www.w3.org/2000/svg">
> <svg:polygon fill="none" points="52,203 0,124 186,0 238,80 52,203 "
> stroke="rgb(255,0,0)" stroke-width="0"
> xmlns:svg="http://www.w3.org/2000/svg"/>
> </svg:symbol>
> </svg:filter>
> </svg:defs>
> <svg:img height="270px" width="480px" "http://example.com/image1.jpg"
> filter="url(#c1)"/>
> </x:svg-fragment>
> </r:Description>
> </r:RDF>
> You can define the mask in that same file (as done above) or in a
> different file, so you will basically get what you want for free with
> the @filter and relative url there.
> Sure, this will work. But if I have 10 annotations to the same fragment, I need to redefine it every time. This is all the purpose of referring to it :-)
> No you don't.
> There is a  filter="url(#c1)" thing that you can use in SVG to link to the same mask as often as you like. Further, you can just put the mask into a separate SVG file and link to it as filter="url(mask.svg#c1)" . Total flexibility!
> Cheers,
> Silvia.

Research Group Multimedia Information Systems
Department of Distributed and Multimedia Systems
Faculty of Computer Science
University of Vienna

Postal Address: Liebiggasse 4/3-4, 1010 Vienna, Austria
Phone: +43 1 42 77 39635 Fax: +43 1 4277 39649
E-Mail: bernhard.haslhofer@univie.ac.at
WWW: http://www.cs.univie.ac.at/bernhard.haslhofer
Received on Friday, 10 September 2010 06:51:27 UTC

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