Sorry, I’m even more late to the party!
Here’s a to-scale map/3D model that I made for an outdoor event using the free version of Sketchup. It took me a couple of days to trace the boundaries of the site, structures etc off Google Earth data (which you can import directly into the Sketchup model), build the model and then plan the fly-through (which starts at 03:59): https://www.youtube.com/watch?v=b186I5LRIzQ
This video totally needed more editing and narrating by someone with a less soporific voice, but never mind, you can get the idea from it
Of course, it doesn’t have the other features of a system like EventOPS though.