Blend4Web is an add-on and SDK for Blender. It enables your to export 3D content from Blender into a web format that can be viewed over the internet with no special plugins or software.
Blender is a 3D editing and development program with a long history of being free and open source.
Drones can be programmed to fly and autonomous grid over a location while taking an array of photos. These images can then processed by software like Pix4D and OpenDroneMap to create a 3D model of the land.