Skyline in augmented reality

I have a project to make a skyline recognition android or web app. A user can use his camera to look at the landscape with augmented reality I want to add an overlay that represents the skyline. I wanted to use gps and gyroscope. I have if necessary .hgt files of the area in which we want to use the application. Do you know which sdk, technologies (unity, unreal,...) or framework to use ? I found only theory unfortunately and nothing concrete.