On 5/27/2016 12:07 AM, Bald Eagle wrote:
> Stephen <mca### [at] aolcom> wrote:
>
>> The default value is: right<1.33,0,0>. This means that the +x-direction
>> is to the right. It is called a left-handed system
>
> I would say that there is a definite handedness to POV-Ray, given the sign of
> different directions on the axes, and the direction of rotation around the axes
> in the (+) direction, I'd have to say that there's a default and inherent
> chirality.
>

I would say so too.
I know that if I use an image map and RH handiness in Bishop3D. The 
image is reversed. Likewise PoseRay, on its PovRay output tab. States:
Right handed (PoseRay default) Y up
Left handed (POV-Ray default) Y up

I also used Moray where Z is up and am quite aware of all the kerfuffle 
around this topic.



> Left-handed coordinate system, and "left-hand rule" for determining things like
> direction of rotation or direction of a normal.
>
> But that's my take as an organic chemist, casual and incidental student of
> physics and POV-Ray (l)user.
>

Personally I prefer the Y up because when I started work as an 
Electronic Engineer, in the early 70's. The Z axis*, on an oscilloscope, 
could be used to control the brightness of the waveform simulating depth.

<Aside> I seem to remember from that distant past. I was told that 
engineers use the Y up, from the oscilloscope example. And that 
mathematicians prefer the Z up coordinate system because they visualise 
a XY graph on paper with the Z axis coming up from the desk. It doesn't 
hold but it helps me visualise converting from one system to another.


* It was called the Z buffer.

# If you think I am using too many commas. It is to keep Dr. John amused. :)


-- 

Regards
     Stephen

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