Thank you all for the feedback. As mentioned by someone else above, the flat side if the Corian produces an image that is less sharp. This is because Corian is very good at conducting light. When the light enters the sharp cut edges and hits flat non cut material the light scatters and diffuses yielding an image that appears out of focus. The thinner the material the better, but when the light passes through the flat side it diffuses the light that then gets conducted to the sharp points and edges yielding much sharper images. Here is an image of the flat side to demonstrate what I am trying to explain.
I used the following website to generate an STL file from an image file. Specify the size on the Model Settings page. I used a minimum layer thickness of 0.6mm. Also ensure you choose positive image on the Image Settings page. Another tip is to lower the vectors per pixel to three to reduce the number of polygons in the STL. With the default vectors per pixel setting at four, the STL file is massive and it takes forever to generate footpaths.