[rp-ml] Colour STL files?

I was updating the Wikipedia article on the STL file format because it
contained no information whatever about the binary varient of the STL
format. (It does now!)

Someone commented that in binary STL's there is a way to represent
colour information...possibly two alternative ways...because SolidView
and Magics use different STL varients.

I've looked around on the net and failed to find anything about this.

Could someone give me definitive information on how that colour data is
stored so that I can stick that into the Wikipedia article also? I'm
guessing that the two byte 'length of auxiliary data' field at the end
of every triangle record is set to some non-zero value and that the
colour is packed in after that. But how is the colour represented?
Three floating point values (Red/Green/Blue) would seem obvious - but if
two manufacturers each do it differently, then maybe someone is using
three bytes or some other representation like a colour pallette or some
alternative colour space or something.

FYI: The Wikipedia article is here:

    http://en.wikipedia.org/wiki/STL_(file_format)

Many thanks in advance.

     Steve.
Received on Wed Nov 22 07:21:19 2006