How can I get value from every corner of my perspective camera in a 3D scene. I am using the library Three.js.
To be more precise, I will mark what I want to know with the following sign:

What coordinates do I need to know:

I need this because I create a real-mode map engine with movement in a 3D scene using the mouse cursor.
What I'm trying to achieve is available here:
http://www.zephyrosanemos.com/windstorm/current/live-demo.html
As you can see, in this example, the new terrain loads with the intersection of the new location (which was not previously available with garbage collection when the camera leaves the old viewport):

Now I want to show part of the screen from my three.js application:

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... , :)
user2402179