unity – Minimap Render texture Mouse Hover Detect on 3d Object in world space

Your minimap is just another buffer you render to. Same as the screenbuffer, it holds no information other than the pixel rgba values.

What you need is a translation between minimap coordinates to worldspace coordinates. So that e.g. the, say, 400×400 px the minimap takes up on your monitor, map to the 1000×1000 area of worldspace you display on that minimap.

So with the above values we select minimap-pixel 200/100, we get world-space 500/250.