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Consider Timeline
class
#2279
Comments
Reflexive, shallow thoughts: Having two ways to do time-only resources helps backwards-compatibility but is confusing for new adopters. I'd think formal deprecation of Canvas for time-only resources would be good, though I don't begin to know the way that would go down. It also feels awkward for video. With Timeline, we'd have resources in categories Visual, Time, 3D and Visual+Time (video). This is probably the overly literal part of my brain reacting, but I also think it's worth some consideration on how video use is accommodated and what the community interaction is going to be like around the changes. |
From the perspective of an developer, Also a bit off topic to the discussion but I wonder how under the idea of this new Container, "Scene" you plan on defining the 2D aspect of the 3D scene, which at the end, from a |
My sense is that I'd take a single way to do things, even if it's not as linguistically elegant, over two ways to do a thing. My preference is to stick with Canvas and add Scene if that's something that you need for 3D, since it's going to be quite different! |
Well, it looks clean and simple. But I cannot really comment w/o considering the scenarios that should be supported by this data structure. Let me try. Although this might lead us down the garden path into the banal.
I also have the feeling that there is a distinction between "scene" and "scenery". The latter sounds static to me while "scene" is more movie-like, the change of something over time. I hope this helps by any means. I just won't jump to new terms that are in common use somewhere else with a different meaning for us. And I don't have a final opinion as long as the kinds of media that should be represented by IIIFpresentationV4 is blurry in my head. Update: I was looking for a corresponding 3D metaphor to canvas. I came up with » stage « |
I really like the idea of separating the basic types based on their basic presentation and interaction model: 1d I think the question of compatibility is a separate concern that needs to take into account how the parallel use of V3 and V4 (and V2?) is envisioned. If V4 is mainly introduced for new resources and new clients for e.g. 3d content then backwards-compatibility is not so important and I would vote to deprecate duration-only Canvases for V4. The Internet Archive's V3 time-only Canvases will remain V3 which is fine for all the existing V3 clients. Clients that want to accommodate both V3 and V4 have to do a bit of translation which seems easier than dealing with both V2 and V3 today (knowing nothing about the rest of V4's changes ;-). |
Thank you all. As expected, mixed feelings. To be clear, If we had tackled 3D and introduced Now that we must introduce a new class Or is it the case, as it quite strongly made by some above, that that ship has sailed, and the potential simplification for newcomers does not outweigh the undesirable task of explaining that you used to be able to use a Canvas as a Timeline, that it's still allowed in V4 but deprecated, etc. A So to rephrase it's a choice between: Three classesTimeline
Canvas
Scene
Two classesCanvas
Scene
There's an opportunity to discuss this in tomorrow's TSG (Wednesday) for those attending. |
Presentation 3 only has
Canvas
as content carrier, which can either have dimensionswidth
,height
,duration
, or justduration
(e.g., for audio).Presentation 4 will introduce a
Scene
class, an unbounded, 3D space. This is necessary as 3D is fundamentally different and extending Canvas, while simple, would not be practical for 3D implementations.Given that we MUST now introduce more than one content carrier, we could use Presentation 4 to introduce another new class
Timeline
, to use instead of Canvases witht
dimension only.This has much simplifying potential in the spec, for rules on dimension compatibility. And the conversion from Presentation 3 to 4 would be to simply change the
type
of time-only canvases toTimeline
, leaving everything else as-is.However...
There are millions of audio-only manifests with Canvases having
duration
-only that, we think, will already be valid Presentation 4 manifests too, if we don't make this change. E.g., all the recent Internet Archive audio manifests.We would end up with:
Timeline
A virtual container that represents a bounded temporal range, without any spatial coordinates.
Canvas
A virtual container that represents a bounded, two-dimensional space and has content resources associated with all or parts of it. It may also have a bounded temporal range in the same manner as a Timeline.
Scene
A virtual container that represents a boundless three-dimensional space and has content resources positioned at locations within it. It may also have a bounded temporal range in the same manner as a Timeline.
Feedback very much appreciated!
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