Show Camera View on HTML Element

If you have ever played an Age of Empires 3 match, you will see that the Mini-map displays the Game Camera’s view on it. This is seen below.
image

I want to do that same thing for my game, since I have the Mini-map already displaying the map. This is done by using adding an Orthographic Camera to the Game Scene. There is a separate renderer from the Game Renderer that within the HTML Element on the bottom right of the screen (you can see this in the screenshot below). This renderer uses that Orthographic Camera to display the Game Scene. The Game Renderer using a Perspective Camera. This means that one Renderer displays the game and the other displays a top-down view of the Mini-map.

In the end I want it to look like this (it’s a simple drawing but it should make sense) picture below.

Essentially what I am asking is: How do I Show the Game Camera’s (Perspective Camera) view on the Mini-map Renderer (that uses the Orthographic Camera).