Am 04.10.2016 um 18:09 schrieb lelama:

> The doc says that povray is a left handed system and uses the left hand for both
> the axis relative locations and the rotations. It was not clear to me when I
> read the doc whether I can change the default behaviour and use the left hand
> for the axis and the right hand for the roations.

You cannot.

> The default choices are clearly documented. But, what if we change the default
> convention ?  I see no place in the doc where it is written if we can make the
> choices for the axis and for the rotations independently.

Actually this is not a matter of choice of the coordinate system -- it
is a matter of choice of how to represent rotations.

As Jerome already mentioned, there is a very strong consensus across
disciplines of theoretical and applied science of what constitutes
positive rotation around an arbitrary vector in any given coordinate
system. Tools produced by individual laymen may occasionally deviate
from this consensus, but so far I haven't seen any professional,
semi-professional or even major hobbyist tool that implements rotation
differently.

POV-Ray's documentation therefore does not make much effort to explain
that there is, in theory, a choice to be made there, and instead just
documents how POV-Ray does it.

You may be confused by POV-Ray /not/ mentioning this theoretical
possibility; other people might experience it as unnecessarily confusing
if POV-Ray /did/ mention it (/especially/ because POV-Ray does not allow
a choice there).

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