Discussion Our goal was to design a visual cue invocation scheme that is - compared to the 3-level scheme - less obtrusive for low NfA-scores and more obtrusive for high NfA-scores. We believe that we succeeded with regard to these requirements. In order to proof this hypothesis, a follow-up experiment has to be performed where both schemes will be compared with regard to a set key performance indicators, such as monitoring behavior, error detection rate and user acceptance. Because there are many working environments where human operators have to monitor information on digital map displays (e.g., air traffic control) we believe that our results could provide a contribution to related domains. There are two concerns with regard to the validity of our results. The first concern is that we did not perform the studies with real end users. This concern is hard and we need to discuss our results with domain experts. The second concern is that the scheme does not provide a solution for off-screen objects which are typical for map displays. Therefore, it is necessary to design a solution for this case.
Summary In this paper, we presented two participatory design studies. The studies were performed to design a visual cue invocation scheme to improve the monitoring behavior of human operators in charge of supervisory control of many UAVs using a digital map display. The result is the halo scheme which uses the dimensions color, size and opacity, and the transition mode continuous to attract attention in a convenient way.
Acknowledgements This research is conducted within the European project D3CoS and funded by ARTEMIS-JU and national authorities under grant agreement no. 269336.