A Fly-Through path is a vector object, either a polyline or polygon, that a Fly-Through follows over a 3D surface in the 3D View. You can either use an existing vector file such as a DXF, SHP or BLN, or you can digitize a new vector object (steps below). Please note that the vector file and the GRD file must be in the same coordinate system and be spatially overlaid for the Fly-Through to work.  

1. In the Plot window, open a GRD file that you will be creating a Fly-Through for as a Post, Classed Post, Base from Data, 3D Surface, Contour, Color Relief,or 3D Wireframe map.
2. With the Map frame selected in the Contents window, click Home | Add to Map | Layer | Empty Base.
3. In the Contents window, select the new empty base map layer.
4. Click Features | Insert | Polyline. You can choose to draw a polygon instead if you prefer.
6. In the Plot window, digitize a line where you would like your Fly-Through path to be located.
7. When finished, press ESC to exit Draw mode.
8. You will now be able to select this vector object as the Fly-Through Input Vector Path in the Flight Path Editor dialog.

Updated April 8, 2020