I've been having a lot of problems with fog, and it looks to me as if the 
settings between the GUI and the exported code have flipped the offset and 
the altitude.

If I put in an offset of -100, and an altitude of 10, I get:

  fog_offset   -100.0
  fog_alt      10.0

That LOOKS correct on the face of it.  However, the POV Doc's says:

For ground fog, the height below which the fog has constant density is 
specified by the fog_offset keyword.

So 'offset' is more like 'altitude'.

The POV Doc's say: The fog_alt keyword is used to specify the rate by which 
the fog fades away.

So 'alt' isn't really an altitude, it's a rate of decay.

Maybe no one else has a problem with this but I really pounded my head 
against the keyboard on this one.  I would recommend changing the GUI labels 
somewhat to be more descriptive (given the same POV Ray keywords).

        == John ==

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"John D. Gwinner" <joh### [at] cornelledu> schreef in bericht
news:421e295b$1@news.povray.org...
> I've been having a lot of problems with fog, and it looks to me as if the
> settings between the GUI and the exported code have flipped the offset and
> the altitude.
>
> If I put in an offset of -100, and an altitude of 10, I get:
>
>   fog_offset   -100.0
>   fog_alt      10.0
>
> That LOOKS correct on the face of it.  However, the POV Doc's says:
>
> For ground fog, the height below which the fog has constant density is
> specified by the fog_offset keyword.
>
> So 'offset' is more like 'altitude'.
>
> The POV Doc's say: The fog_alt keyword is used to specify the rate by
which
> the fog fades away.
>
> So 'alt' isn't really an altitude, it's a rate of decay.
>
> Maybe no one else has a problem with this but I really pounded my head
> against the keyboard on this one.  I would recommend changing the GUI
labels
> somewhat to be more descriptive (given the same POV Ray keywords).
>

Hi John,
<grin> glad (?) to see others have also confusion on this issue :-)
Fog_offset is indeed the altitude below which the fog is constant; and
altitude is indeed the rate of decay of the fog.... very confusing.
The problem is not with Moray, nor really with Pov, but with the terminology
indeed. I confess that I had also constantly problems with knowing exactly
what was going to happen. I solved it by making a little drawing for myself
explaining how things worked. I must say that since then the problem was
solved.

Thomas

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