Hi Justin,
These questions strike at the heart of some of what I think are the key unresolved aspects of DarwinCore – aspects that I hope will be the focus of some specific attention at the next TDWG meeting.
I will provide some answers from my own personal perspective.
In my mind, Location = Place (and all metadata associated with describing a place in three-dimensional space).
Event adds the fourth dimension of Time (i.e., Place + Time). Depending on who you talk to, Event may also include metadata related to “who” (which doesn’t necessarily need to be a human – it might involve telemetry devices as well). And, assuming there is some sort of sampling activity associated with the Event, there may be some metadata related to that sampling and its methodology.
I’m not entirely sure what you mean by “snapped” for Timer tracks. Does “snapped” refer to capturing images or some other sort of other data capturing protocol? Or does “snapped” simply mean that you log a timestamp and Lat/Long coordinates? If the latter, then I would treat each node on the Timer track (i.e., each “snap”) as representing an Event (Location + Time). If something other than the simple logging of Lat + Long + Time happens at each “snap”, then that opens up another set of issues which I’d be happy to comment on.
Likewise, presuming that each Sighting comes with its own Lat/Long (Location) data, as well as a time, then these, too, would represent Events. But anything documented at those Events (e.g., sightings of an individual organism) would represent Occurrence instances. Non-biological documentations (such as weather) would probably best be represented as properties of the Event. In DwC you’d probably express those in dwc:fieldNotes or dwc:eventRemarks.
A different (and equally legitimate) interpretation of how to represent Timer tracks in DwC would be to represent the entire Track as a single Event, capturing the “Location” component as a sequence of Lat/Long points (effectively describing a linear path as a single location), or as a simple polygon (bounding box or point+radius), and the “time” component as a range from the time of capture for the first “snap” to the time of the last “snap”.
My own personal approach (which extends beyond what DwC:Event class is currently set up to accommodate) would be to do both for your timer tracks. That is, represent one Event as the entire track, with the Location described either with an ordered array of Lat/Long points or as a bounding box or point+radius that describes the smallest rectangle or circle that encompasses all of the points, and range of min-max timestamps to represent the Time component of the Event. Then I would capture each “snap” on the track as a distinct Event (in our data model, we support hierarchical events, so the individual points would be referenced as “child” events of the “parent” Event representing the entire track).
I’m not sure if that helps or only confuses things; but perhaps after the next TDWG meeting we might have more clarity and/or consensus on these issues.
Aloha,
Rich
From: tdwg-content-bounces@lists.tdwg.org [mailto:tdwg-content-bounces@lists.tdwg.org] On Behalf Of Justin Steventon
Sent: Sunday, July 21, 2013 10:32 AM
To: tdwg-content@lists.tdwg.org
Subject: [tdwg-content] Data capture software and Darwin Core
Hi folks,
Just starting to get into Darwin Core. Thanks for any help and suggestions you can provide.
I’m the builder of a data capture application (using PDAs and smart phones) called CyberTracker (http://www.cybertracker.org). We want to create a feature to export to Simple Darwin Core as XML.
We have two kinds of data: timer tracks and sightings. Timer tracks are automatically snapped at regular intervals and only contain a timestamp and location. Sightings are manually captured data and vary quite a bit. For example, they could represent the weather or a direct sighting of an animal.
It seems clear that a sighting maps directly to an “Event”.
If we have a long list of timer track points, should these show up as many “Location” records?
Regards,
-Justin