If I use the optimize operation, nothing happens, never.

The number of faces/points never changes? In some cases this is because I have added automatic optimization to many of the operations. But, there should be some cases still where it has some effect. I don't think it is obsolete yet, but may be soon.

If I divide a face and after that I use optimize, nothing happens too. Or isn't that where optimize is used for?

Optimize operation is useful to correct geometry problems, correct some faces or remove redundant points (after weld operation for example or a boolean operation).

is there a way to make one face of a lot divided faces?

The Consolidate operation may do it. It isn't enabled by default. You'll need to enable it via "Tools->Options->Operations". Just put a check mark next to where it says "Consolidate". That will make it available from the "Object Operations" panel.

quote:

Originally posted by Amabilis Support:
The Consolidate operation may do it.

Well, an operation I wasn't aware of.
I enabled it but it cannot be used (at least I didn't find how): it seems that the icon is greyed.
Is it the one between chamfer and divide (because of the alphabetical order)?

Consolidate is extremely useful.

You select a whole object, run the operation and it reduces the poly count without changing the geometry (in certain circumstances)

e.g.
http://forums.uktrainsim.com/viewtopic.php?f=18&t=43773

quote:

Originally posted by Paul Gausden:
You select a whole object...

So it works on the whole object, not on selected faces (as I tried to use it).
Thanks.