- From: Al Gilman <asgilman@iamdigex.net>
- Date: Sun, 09 Sep 2001 09:39:13 -0400
- To: Loretta Guarino Reid <lguarino@adobe.com>, Charles McCathieNevile <charles@w3.org>
- Cc: Loretta Guarino Reid <lguarino@adobe.com>, Ivan Herman <ivan@w3.org>, Marja-Riitta Koivunen <marja@w3.org>, WAI Cross-group list <wai-xtech@w3.org>, lguarino@adobe.com
At 06:59 AM 2001-09-09 , Loretta Guarino Reid wrote: >Is this a fair summary? > AG:: ** summary Almost. Don't write off a dump option. There is always a usable dump into the world of DAISY books. And there is more summary possible about what the authoring tool needs to provide in terms of meta-stuff in the SVG to support full viewing flexibility and intelligence when the mode is more interactive. ** details * dump format If you dump to hypertext, then the result is interactive. There is no non-interactive option on the table. [yes, richer interaction is better for some people.] An exhaustive dump to hypertext is always possible and if the DAISY talking book design is taken as the master pattern that one is dumping to, and one uses that pattern semi-well, then the result need not be confusing. Of course if the main plot of the graphical presentation is a cycle, as in the first graphic in The role of User Environments in The Grid <http://trace.wisc.edu/docs/ud4grid/#_Toc495220373>http://trace.wisc.edu/do cs/ud4grid/#_Toc495220373 Then you need to know what you are doing. Here graph navigation, following the principal relationships in the plot-graph for the story depicted in the graphic, encoded as hyperlinks in the hypertext, makes the story clearer than just a tree or linear narrative alone. This is a document design you can trust because it closely follows what is known from field experience to work, and the differences were developed by experts close to the consumers in the field. Note that as I said this requires at least two planes of static hypertext, a table of navigation which provides global orientation and the full-text version. * support for interactive data browsing A yet more interactive data browse is better for some people, as you note. The nominal first path here is with a DOM and assistive technology leading the view formation dialog, the interactive decisions about what shows in interactive navigation. Think of what you get with a DOM as data+knowledge. The stuff on hand (in program data space) in the application that writes the SVG consists of data values and knowledge about those data values. Range constraints, relationships and the like. The chart contains a subset of the data. It should logically contain, (which permits machine followable links to) full knowledge about the data included. Every constraint (including relationships as formally constraint patterns) that pertained to the retained data as present in the data space of the active application should be available to the view formulation process in a thick client which may be dominated by AT algorithms. Knowledge that genuinely does not touch the data retained in the chart view is not required, but may be efficiently included through the by-reference mechanism. BUT, I have to repeat a warning. There ain't a'gonna be any rule based on selectors against the visual role alone such as "text on the bars" that will be valid as to when you show what. "text on the bars" is used for too many different underlying roles of label information. I believe this is what Ivan is trying to say, too. It's like italics and Braille. In print, a variety of rhetorical roles lead text to be italicized. In Braille, some of these deserve italics, and some of them don't. So for repurposing to literate Braille (and Braille is so effects poor that you had better generate literate stuff or it is truly painful to read) one has to get behind the visual effect of italics to discover the precise rhetorical role that was the reason for the italics before you can truly know whether to italicize the text in the Braille edition. The author encodes the structure of their quantitative story by the combination of the graphics and the sense of the labels. You can tell from the fact that a text label is a compatible numeric quantity and its orientation along an invisible coordinate grid line that it is a sample value that is further described by the scale laid out along the margin. There is some type-matching that goes into the cognitive processing that connects this text fragment in the layout with the scale fragment in the layout. That cognitive alignment is in the 3D virtual world evoked by the 3D bar chart, by the way, not in the 2D that the SVG draws. This kind of "Oh, that is_a [stock price]" inference that the visual user infers from alignment in the virtual world is some of what Ivan is talking about one has to spell out or the extraction to a tree of topics in a linear narrative will not be constructable by rote algorithm. LG-R:: >And, of course, this all gets more complicated if the bar chart is just >one object in a larger SVG file. > AG:: It gets simpler if you take a generic object view. But of course XML doesn't let you, so there is a whole hassle about how the meta-information for a modal, multilevel world such as a poster layout with embedded 3D scenes in it is captured and shared in an XML file. But this is a generic XML document problem, not unique to graphics. This part is complicated, not hard. If you approach the design of a schemas and namespaces use plan to get the information into XML with a clear idea in mind of the kind of world you are constructing, where each object class carries its own content-ontology which can be different from the ontology governing the space the object is embedded in, then it is a small matter of programming. A review of the logical flow through the X3D work is instructive. What I am saying is that if you understand what good capability is, here, and approach the dialect design with that as your objective, I believe you can do it in XML, yea in something very like SVG 1.0 or SVG 1.0 + namespaces. But XML doesn't help you. You have to know what you are after. And the Ap that writes the SVG has to put the necessary knowledge backups _in_ or the assistive view extraction cannot get what it needs to get a literate reading _out_ of the SVG data. Al At 06:59 AM 2001-09-09 , Loretta Guarino Reid wrote: >Part of what I wrestle with, in the bar graph example, is what to do >with the text that is part of the rendered visual representation. Should >that be included in the linearization? Unfortuneately, I think I get >different answers if the text is the labels on the bars (Australia, >New Zealand, etc.) or if the text is the caption for the table. I suspect >we don't want the former, by default, but we do want the latter. > >And, of course, this all gets more complicated if the bar chart is just >one object in a larger SVG file. > >The impression I'm getting, from this discussion, is that a user agent needs >to provide interactive navigation for such structures, that an author >should be prepared to have the user presented with only the top level >description, as well as having the user navigate the structure >dynamically, and that a full non-interactive linearization is likely to >be confusing. > >Is this a fair summary? > > Loretta >
Received on Sunday, 9 September 2001 09:16:11 UTC