accessible images (diagrams)

Hi,

Here in Brazil we have a group trying to implement image accessibility for
some blind students.

The idea is that diagrams like this:
http://upload.wikimedia.org/wikipedia/commons/7/72/ER_Diagram_MMORPG.pngmust
be accessible to them.

We've been searching over the internet for solutions like a software that
would convert the image into tactile graphics or something like this but it
seems like there's not much information available. A sound version of the
graphic would solve the problem, but it's far nonpratical.

Could anyone help us with some advices?

Thanks in advance,

Régis