map, scene 1, displacement

Bfore I could model the map I had to plan it.  I am following this tutorial on youtube: http://www.youtube.com/watch?v=K9YxcVKizcg.  I know that you need two types of map, one with the textures and one in black and white.  So with this in mind, I decided to go on Google maps and get a picture from that.  I then opened it in photoshop and painted it in black and white (the land in white and sea in black) like so:

 

Now I hope that this 'displacement technique' is going to work as I spent hours on the above picture.  Unfortunately it didn't quite work:

I thought about turning the map black and white on Photoshop, and then take care of the displacement: 

  

Unfortunately that didn't work either as is evident by the picture below: