Thanks for the reply, Emmanuel.

I still have two doubts after your answers, though.

1) In the ObserverCamera class what is the depth returned by getDepth?

It's the depth of the virtual visitor in the plan.

I understand that the elevation is given by Z, right?

Yes

In that case I'm still not sure about what depth means here. Is it the level of the house to which the Z elevation belongs or is it another thing?

2) On the Camera.Lens enumeration does PINHOLE correspond to "depth of field"?

It's the NORMAL lens. A PINHOLE camera matches a very small hole in a black box, i.e. no depth of field because of a very small aperture.

So, if the "depth of field" lens is the NORMAL lens, how do I specify whether I want to use just the normal plain lens or the "depth of field" lens?