how to create a 3d mosaic out of a 2d image i have a  mosaic image and i want to turn it into a plan object that is going to have a 3D bumps.the result is going to be printed with a 3d printer .the idea is to extract the parts of the image so i can feel them with my hands 
i still didn't try any method and i don't know where to start.
The only automation you can have is to translate the brightness value of every pixel into a height map, setting it as texture in a displace modifier on a highly subdivided plane. The result is quite random because of the problems Martin Z said. In my example we have 1.500.000 vertices.