This post is as much about initiating discussion as it is about my own thoughts on the matter, so feel free to comment away, here, or twitter, or google+ or wherever – I’m interested in thoughts and perspectives.
So… 3D PDFs. They seem like a really good idea right? You can encapsulate 3D information to share with people. Stephan Lautenschlager wrote a workflow on producing them, and in it he stated:
“The ability to integrate three-dimensional (3D) models, which can be interactively manipulated, into portable document format (PDF) documents not only considerably improves their accessibility, but also represents an innovative, but so far neglected, approach for the presentation and communication of digital data… …As both authors and readers benefit greatly from their usage, it is argued that 3D PDFs should become an accepted standard in palaeontological publications of three-dimensional models.”
Now, I want to stress that I’m not having a go at Stephan, he’s absolutely right. What I want to discuss is in what he’s right with: “Presentation and communication of digital data.” The problem with that, is that it’s not “sharing digital data.”
3D PDFs fill a weird kind of niche – they contain all the 3D information, and allow users to manipulate that 3D data to view it however they wish. Obviously this is vastly superior to a video of a rotating model, it lets you tilt the object, zoom, and really look at everything you want to see, including things the author of the model didn’t think you’d want to see.
But that’s just teasing!
That’s showing the data without letting the reader actually get in there and use it. As far as I can see, there are two main advantages to supplying data as 3D PDFs:
- People can easily view it without specialist 3D software. (The ‘improves accessibility’ point by Lautenshlager)
- The data cannot be easily used by other people before you’re willing to share the raw 3D data.
Unfortunately, I’d say there are some pretty strong arguments against both these points. Point 1 is good in theory, but in reality a) people who are interested in the 3D model probably have, or are competent enough to get, meshlab, or something similar. B) Not all PDF readers are equal, and a lot of the non-adobe readers can’t open 3D PDFs (for instance, Adobe Reader Touch and Windows Reader can’t, I know I’ve had issues with Foxit and some Android PDF readers too, I’d be interested if all or some mac/ipad readers can), and this just exacerbates the problem, because now we have people for whom the 3D PDF just doesn’t work – if they’re lucky they’ll get a static image. The one time I would say that this point is valid is in complex scenes that can’t be exported as a single 3D file: visualizations of flow, for instance, can’t be reduced to a single 3D file for people to open in meshlab, but benefit from being viewed from any angle. Or perhaps virtual dissections, in which parts can be turned on or off with buttons (arguably, each part could be provided as a separate 3D file and opened together as layers in a 3D program like meshlab).
As to point 2, well, the arguments have been well trodden and discussed about sharing data and how important it is. ‘Hiding’ it in plain sight in a 3D PDF is a bit cheeky really, I think.
Except… There are ways to get 3D data out of a 3D PDF. They aren’t that common or easy yet, but it can be done. It can be as simple as having a specialist piece of CAD software that can natively open PDF files as raw 3D data.
And so we get to the part where I’d like your input:
If someone publishes a 3D PDF, is it fair game to take that published data, extract the 3D model, and use it in your own studies (properly cited of course!)? In discussions with colleagues, we likened it to extracting data from a published graph. But is the 3D model raw data, or is it a final figure? Does the journal own the copyright to the formatted 3D PDF submitted as supplemental data, or the data within it (surely it’s just the former, much as an unformatted manuscript remains the copyright of the author?)?
One has to ask of such data, why did the authors provide it as a PDF in the first place? It seems far easier to provide such data as OBJ or PLY files (or STL/PTS/XYZ/WRL etc etc) uploaded as supplemental data, perhaps in dryad or figshare. What did the authors feel was the benefit of making a 3D PDF? If it was genuinely to aid accessibility, then presumably they would have no beef whatsoever about another researcher extracting the 3D model. But what if they chose to produce a 3D PDF purely to avoid handing out the raw data?
Maybe I’m underestimating the accessibility angle. Maybe a lot of people do have Adobe reader, but don’t have any 3D software on their computer. My opinion is that there really isn’t any benefit to presenting palaeontological data like digitized bones and skeletons in a 3D PDF, as opposed to just uploading the raw files* and possibly a spinny animation.
The slippery slope
Having thought about and maybe responded to the above, I’d now like to posit to you a continuation of the theme. Advances in computer vision are enabling construction of 3D models from video, if someone uploads a spinning animation of a digitized specimen it could conceivably be reverse engineered [Indeed, this is a little non-palaeo side project I’m tinkering with]… Once again, I ask, is this fair game? Is the data considered published and re-usable? Do we need specific permissions from the original author? If so, why are we treating data in new media (3D models, animations) as somehow different to data in a graph or table?
I don’t know. It’s an exciting time to be working in palaeontology, what with all these new methods to generate, analyze, and communicate data. It’s something of an adaptive radiation of methods, if you will. But a side-effect is that we’re left wondering what is acceptable, expected, or necessary? As with all such explosions of accessibility in the digital world, there are two options; we can either try to crack down and control dissemination of data, or we can go with the flow; not just accepting it but actively encouraging it.