Importing assets from Maya to Unity

Once I modelled my Spaceship in Maya i rendered it out from a top down perspective using the Maya hardware renderer and set the format as a PNG as that supports a alpha channel and that will be need when importing into unity. When the image of the spaceship is rendered out I then loaded up unity and and dragged and dropped my render into my projects window and then the hierarchy to display it in my scene. Because I rendered out a alpha channel with my PNG when I add something like a 2D polygon collider and it will now accurately create a collider object around my asset using the alpha channel.