Hello,Forgive my poor Engilish:)
I builded a large map navigation use the ThirdPerson example, and use the default navigation settings.
The picture bellow shows my problem, I let AI move to player, he does not move along the shortest way(the red line).
I test different distance, it also has the problem
Do I need to adjust some Navigation param, such as agent radius or cell size？
If you enabled drawing navmesh polygon edges (it’s one of the options on the RecastNavMesh actor) it would be clear to you why this happens. In general, while working with game AI you need to remember that we don’t aim for simulation-grade results, just “close enough and efficient”. In this specific case, navmesh is a simplification of the world space, and A* is limited to that simplified representation. This is why you’ll sometimes will end up with not exactly what you’d expect in real life.
However, you can have AI move in a straight line. You just need to disable pathfinding 
Cheers,
–mieszko
Thanks very very much, i enabled drawing navmesh poly edges, it is much larger than agent radius.By the way, we are making a game with a large landscape, so we need ai navigation. Does it mean if i want bettter simulation-grade results, the best way is scale down the map size? I will do a test.
