3D trajectory editor based on google/yandex maps

Hello, In our little team we do filming using drones. We would like to provide our customers with ability to draw 3D path for drone flight just on website as simple as possible, click "order" and get the film. All we need now is just very basic working prototype (PoC). Probably, user is suposed to do that in two steps (see attached pictures): – draw a path upon the maps widget – set altitude for each of points It would be great to use PHP or Java on backend. As 3D path should be drawn in client's browser, probably, WebGL is needed, but not necessary, feel free to promote other technology if you find it better. P.S. Not sure about project's budget, let me know if it costs more.