Automated picture taking for ground stitching?

Hi all, I would like to take some straight down pictures over a 500m x 100m box. Capturing multiple pictures (For example, 500 pics @ about 10m x 10m) to be stitched together into a larger image. I've seen that litchi can automate 360 pics, but not sure if anything exists for the multiple captures I need to be able to stitch the area together.

Any advice greatly appreciated. I'm using a Phantom 3 Pro.