adding hotspots to equirectangular image Search this thread...

I have a sphere and I'm using a equirectangular image as the texture for this sphere. I flipped the normals on the sphere so the texture is like a background. I'm trying to make it so that you can mark spots on the equirectangular image and render objects at these locations in unity. So someone could add objects to the unity app by clicking on the 2d image from a website for example. I need to track where they clicked it, and convert this to a unity vector 3d position. For the distance I'll use the radius. I'm trying to come up with a 2d grid system that can be used on the images and converted into a Unity vector position. I've tried using polar coordinates with no luck so far. Help is appreciated, thanks!