*3.2. Design of the Simulation Environment (Virtual Location)*

For the MR simulation, it was essential to design a virtual location in X-Plane similar to the location of the real quadcopter. In this work, a drone airfield was chosen in the permissible east part of Seoul, South Korea. Figure 4 illustrates the chosen airfield location (Hangang Drone Park) in Seoul, South Korea. Note that X-Plane has only the sceneries of major airports, there is no scenery available

for the chosen airfield location (Hangang Drone Park). To overcome this lacuna, a new scenery of the chosen airfield location was designed at the same geographic location using WorldEditor (version: 1.7.2). WorldEditor is a software, which is used to create and edit the scenery for X-Plane.

**Figure 4.** Airfield location (Hangang Drone Park) in Seoul, South Korea.

Note that the small runway in the Hangang Drone Park (see Figure 4) was taken as the initial reference point of the real quadcopter. Therefore, we created a virtual runway similar to the real runway in Hangang Drone Park. In WorldEditor, first, we chose the "create airport" option. After selecting the create airport option, we could see several design tools on WorldEditor, including runway, helipad, objects, forest, sealane, and facades. Here, we used the "runway" tool to build the runway. According to latitude, longitude, heading, and a few other known design parameters highlighted in Figure 5, the virtual location was built similar to the chosen airfield location. Note that the coordinates of the virtual and actual locations needed to be exactly the same, which we achieved; otherwise, an error would occur during the MR simulation.

**Figure 5.** Design parameters of virtual location (on WorldEditor).

The designed virtual location was placed in the X-Plane environment (see Figure 6). Therefore, it was possible to fly the virtual quadcopter from the designed virtual location. Figure 7 illustrates the real and the virtual quadcopters in the real and the virtual environments, respectively (before MR simulation). In the following section, the interface between the real and the virtual quadcopters are presented.

**Figure 6.** Designed virtual location (Hangang Drone Park) in X-Plane.

**Figure 7.** The real quadcopter in the real environment (Hangang Drone Park) (**left**) and the virtual quadcopter in the X-Plane's virtual environment (designed Hangang Drone Park) (**right**).
