Is it too early to look Google Earth’s timeline gifthorse in the mouth? It’s an excellent new tool — so much so that I’m wishing I could do more with it.
Like what? I’ll illustrate by way of example:
1. Add periodicity: Some datasets have a natural periodicity to them — seasonal water temperatures, for example, or the tides, or the daily schedule of ferries in Stockholm. It would be very useful to be able to compare successive equivalent phases in the data.
As it is now, events that happen in successive days, months or years will also appear in the timeline successively. For example, here are the time-enabled trajectories of the 6pm ferry from Stockholm to Sandhamn on August 30, 31, and September 1. Each trajectory leaves separately; but how would these trajectories look relative to one another, timewise?
To find out, I cheated, converting all the date stamps to Sept 1 but leaving the time component unchanged. Here is the resulting file. It’s lovely to look at, as if three caterpillars are racing through the Stockholm Archipelago (if you set your timeline parameters right — I suggest an interval of 2-3 minutes, played as slowly as possible):
It would be cool to build in such functionality into the timeline tool — an option that lets you choose the periodicity of the data (hour, day, month, year, and perhaps week?), and then an option that lets you choose whether you want to show the data for each phase simultaneously or in succession. For example, for the ferries it makes sense to show the data simultaneously, but for overlays showing global snow cover, it would make sense to show December data for successive years in succession, so that long-term trends become visible.
2. Fine-tuning controls: There is currently no way (that I know of) to advance from individual time event to individual time event in a granular way. This makes it harder to navigate precisely, or to ensure that something is always visible, especially if the timeline is set to show just an instant rather than a wedge of time.
By way of example, check out this really innovative use of the timeline, by Virgil Zettterlind at DestinSharks.com. He took a video of a drive through Death valley, associated some video stills to a GPS tracklog, and then plastered the stills onto Google Earth as a ScreenOverlay, to be played as a slide show with the timeline. (Here is the KMZ file directly.) The effect works very well. Just like with the ferries, you should really see this in real life, as a screenshot does not do it justice:
But Virgil had to “cheat” as well. As he explains, he chose to associate the stills with overlapping time spans rather than just the instant they were taken, so that there is no danger of the user seeing nothing at all. And the ScreenOverlay hack is a good way of forcing images to be visible, in the absence of a (documented) way to control the popup balloons.
How would such granular controls work? Well, I’d be happy with a simple keyboard shortcut, but otherwise two extra arrows in the UI would suffice, just as with current multimedia players.
3. A way of controlling timeline settings from within the KML. Virgil’s problem would also be solved if he had the ability to control the timeline’s settings via KML. How the data is presented can make a big difference to what information is highlighted. There should be a better way than telling users what the precise settings should be — as Declan Butler does in his recent post on the revamped avian flu layer. If a layer is best viewed with the the time wedge clamped to the left-hand side, then it would make sense to have the KML impart this preference.
A related topic is that the timeline stretches to incorporate all time-enabled KML files that are currently visible on Google Earth, even if they are far apart temporally, or of a radically different timespan. This means that one or more datasets will become difficult to navigate.
It looks like a more advanced Google Earth API may soon come to the rescue, however. This morning, Let’s Push Things Forward writes about some new undocumented enhanced classes for Google Earth’s component object model, including what sounds like the ability to pop up balloons at will. That would be useful:-)
(Finally, a bug report: On my Mac, the timeline does not seem to adjust itself after layers are turned off. I currently solve the problem by deleting folders in My Places and then restarting Google Earth.)
In sum, the timeline is a wonderful innovation, one for which the possibilities are just beginning to be explored.