[annotator-dev] Request for discussion: non-text annotations?

Simon Rainer Rainer.Simon at ait.ac.at
Thu Nov 22 13:38:14 UTC 2012


< So Openlayers uses lat/lon coordinates? >

For example. But OpenLayers supports a whole range of map projections, so in theory there's actually a vast array of possible lat/long, x/y, north/east kind-of coordinate systems one might encounter. Still, I think a "unit" field set to "degrees" or "meters", and then a custom "projection" field that's only used for maps (and which would default to the standard "Google Maps" projection) should be a good start for this particular kind of use case.


-----Ursprüngliche Nachricht-----
Von: Robert Casties [mailto:casties at mpiwg-berlin.mpg.de] 
Gesendet: Donnerstag, 22. November 2012 13:00
An: Simon Rainer
Cc: Randall Leeds; annotator-dev at lists.okfn.org
Betreff: Re: AW: AW: [annotator-dev] Request for discussion: non-text annotations?

Hi Rainer,

On 22.11.12 12:08, Simon Rainer wrote:
> +1 on the 'units' extension. 'fraction' and 'pixel' for the time
> being? (I'm also thinking about our use case with OpenLayers, which 
> works with map coordinates. So this might be a nice way to handle 
> those cleanly.)

Sounds good to me. So Openlayers uses lat/lon coordinates?

> Regarding shape alternatives: hm. I still need to think through the 
> entire case first I guess. But rather than having alternatives, I 
> think, I'd simply add extra properties to the shape itself. Say 
> something like:
> shape : { type : 'Polygon', geometry : { units : 'pixel',  coords:
> [{x: 10, y: 10}, {x: 100, y: 10}, {x: 100, y: 20}, {x: 10, y: 20}] }, 
> anchorPoint: 0 }

Looks Ok to me. A small thing: I would like to use a lower case type "polygon" similar to the SVG spec.

I like your explicit coordinate pairs for polygon.

> and then 'unaware' clients would simply skip the anchorPoint property, 
> dealing only with the raw shape. Or maybe the fact that it's (in this 
> case) a "placename annotation" shouldn't be encoded in the shape at 
> all, but rather at the level above (as part of the annotation). 
> Anyways: still needs more thinking, I guess, and is part of another 
> discussion, probably :-)

I think the "anchorPoint" is OK since it enhances the shape. Something doesn't have to be a place name to have an anchor point. But I agree that parts specifying the semantics of the annotation should be on the annotation rather than on the shape.

> Regarding multiple targets: Annotorious doesn't have the necessary UI 
> features for handling that use case at the moment. But I agree it's 
> something we need to handle in the format sooner rather than later. I 
> think I'm going to change my 'shape' field to 'shapes' and then simply 
> use a JSON array of shapes, rather than a single object.

Cool, that's what I wanted to do too. And our UI doesn't deal with multiple targets either...


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