They had badge scanners didn't they?
They would have mapped this to XY coordinates and then dumped an image behind.
Edit: Somewhat similar to the background image here: http://www.datadrivenconsulting.com/2011/03/tableau-us-map-with-alaska-and-hawaii/
or the one I saw with teeth a while ago...
yeah, I understand how they created the visualization and mapped the image.
I'm not aware of how they captured the data. We wanted to do something similar at a partner conference coming up soon. Badge scanners make sense, but not sure of the difficulty to implement. We were thinking of getting participants to scan QR codes.