This video explains how.
Please note that the video maker shows how it's done when he starts the process on a PC, not on a iPad. I have no idea whether you can pull the same stunt off using an iPad or some other medium. Similarly, I have no idea if the same can be done using gpx routes from say Kurviger or something similar. Anyway, it matters not. Give it a go using whatever you like, you can't break it.
<iframe width="560" height="315" src="https://www.youtube.com/embed/J8bXd3XQ2z4" frameborder="0" allow="accelerometer; autoplay; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe>
Please note that the video maker shows how it's done when he starts the process on a PC, not on a iPad. I have no idea whether you can pull the same stunt off using an iPad or some other medium. Similarly, I have no idea if the same can be done using gpx routes from say Kurviger or something similar. Anyway, it matters not. Give it a go using whatever you like, you can't break it.
<iframe width="560" height="315" src="https://www.youtube.com/embed/J8bXd3XQ2z4" frameborder="0" allow="accelerometer; autoplay; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe>