texture mapping with intermediate surface

Hello.

I'm searching for how to draw a texture on terrain surface such as the 'google earth'.
Google Earth supports an image overlay function.
That image is attached exactly on terrain surface.
Even a boundary of that image is an arbitrary quadrangle.
It's exactly what i want to.

You can see the similar function at the following link : http://vterrain.org/Misc/draping.html
i want to develope that function with WPF.
Do you have any idea?

Actually, I have an idea that texture mapping with intermediate surface.
But I don't know how to apply it with WPF.

Let me know please.