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From: Mike Horvath
Subject: Spectral locus
Date: 12 Mar 2017 08:42:04
Message: <58c5421c$1@news.povray.org>
On Wikipedia it says, "In color spaces which include all, or most 
spectral colors, they form a part of boundary of the set of all real 
colors. If luminance is counted, then spectral colors form a surface, 
otherwise their locus is a curve in a two-dimensional chromaticity space."

Is it acceptable to use the term "locus" to refer to a surface as well 
as a curve? Or is does "locus" only refer to curves?


Mike


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From: Mike Horvath
Subject: Re: Spectral locus
Date: 12 Mar 2017 08:44:27
Message: <58c542ab$1@news.povray.org>
On 3/12/2017 8:42 AM, Mike Horvath wrote:
> On Wikipedia it says, "In color spaces which include all, or most
> spectral colors, they form a part of boundary of the set of all real
> colors. If luminance is counted, then spectral colors form a surface,
> otherwise their locus is a curve in a two-dimensional chromaticity space."
>
> Is it acceptable to use the term "locus" to refer to a surface as well
> as a curve? Or is does "locus" only refer to curves?
>
>
> Mike


Merriam-Webster says a locus is, "the set of all points whose location 
is determined by stated conditions". It doesn't specify whether the term 
refers only to curves and not to surfaces. Still not 100% sure though.


Mike


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From: Stephen
Subject: Re: Spectral locus
Date: 12 Mar 2017 09:00:46
Message: <58c5467e$1@news.povray.org>
On 3/12/2017 12:42 PM, Mike Horvath wrote:
> On Wikipedia it says, "In color spaces which include all, or most
> spectral colors, they form a part of boundary of the set of all real
> colors. If luminance is counted, then spectral colors form a surface,
> otherwise their locus is a curve in a two-dimensional chromaticity space."
>
> Is it acceptable to use the term "locus" to refer to a surface as well
> as a curve? Or is does "locus" only refer to curves?
>

It is to me. ;)
 From this definition: a curve or other figure formed by all the points 
satisfying a particular equation of the relation between coordinates, or 
by a point, line, or surface moving according to mathematically defined 
conditions.

A sphere fits that description. All points equidistant from the centre.

-- 

Regards
     Stephen


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From: Mike Horvath
Subject: Re: Spectral locus
Date: 12 Mar 2017 09:22:55
Message: <58c54baf$1@news.povray.org>
On 3/12/2017 9:00 AM, Stephen wrote:
> On 3/12/2017 12:42 PM, Mike Horvath wrote:
>> On Wikipedia it says, "In color spaces which include all, or most
>> spectral colors, they form a part of boundary of the set of all real
>> colors. If luminance is counted, then spectral colors form a surface,
>> otherwise their locus is a curve in a two-dimensional chromaticity
>> space."
>>
>> Is it acceptable to use the term "locus" to refer to a surface as well
>> as a curve? Or is does "locus" only refer to curves?
>>
>
> It is to me. ;)
> From this definition: a curve or other figure formed by all the points
> satisfying a particular equation of the relation between coordinates, or
> by a point, line, or surface moving according to mathematically defined
> conditions.
>
> A sphere fits that description. All points equidistant from the centre.
>


Okay thanks.


Mike


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From: Stephen
Subject: Re: Spectral locus
Date: 12 Mar 2017 09:43:55
Message: <58c5509b$1@news.povray.org>
On 3/12/2017 1:22 PM, Mike Horvath wrote:
> On 3/12/2017 9:00 AM, Stephen wrote:
>> On 3/12/2017 12:42 PM, Mike Horvath wrote:
>>> On Wikipedia it says, "In color spaces which include all, or most
>>> spectral colors, they form a part of boundary of the set of all real
>>> colors. If luminance is counted, then spectral colors form a surface,
>>> otherwise their locus is a curve in a two-dimensional chromaticity
>>> space."
>>>
>>> Is it acceptable to use the term "locus" to refer to a surface as well
>>> as a curve? Or is does "locus" only refer to curves?
>>>
>>
>> It is to me. ;)
>> From this definition: a curve or other figure formed by all the points
>> satisfying a particular equation of the relation between coordinates, or
>> by a point, line, or surface moving according to mathematically defined
>> conditions.
>>
>> A sphere fits that description. All points equidistant from the centre.
>>
>
>
> Okay thanks.
>


But remember that I have to take my socks off to count past 10. :)


-- 

Regards
     Stephen


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From: Mr
Subject: Re: Spectral locus
Date: 13 Mar 2017 06:20:00
Message: <web.58c671affcc363e016086ed00@news.povray.org>
Stephen <mca### [at] aolcom> wrote:
> On 3/12/2017 1:22 PM, Mike Horvath wrote:
> > On 3/12/2017 9:00 AM, Stephen wrote:
> >> On 3/12/2017 12:42 PM, Mike Horvath wrote:
> >>> On Wikipedia it says, "In color spaces which include all, or most
> >>> spectral colors, they form a part of boundary of the set of all real
> >>> colors. If luminance is counted, then spectral colors form a surface,
> >>> otherwise their locus is a curve in a two-dimensional chromaticity
> >>> space."
> >>>
> >>> Is it acceptable to use the term "locus" to refer to a surface as well
> >>> as a curve? Or is does "locus" only refer to curves?
> >>>
> >>
> >> It is to me. ;)
> >> From this definition: a curve or other figure formed by all the points
> >> satisfying a particular equation of the relation between coordinates, or
> >> by a point, line, or surface moving according to mathematically defined
> >> conditions.
> >>
> >> A sphere fits that description. All points equidistant from the centre.
> >>
> >
> >
> > Okay thanks.
> >
>
>
> But remember that I have to take my socks off to count past 10. :)
>
>
> --
>
> Regards
>      Stephen

:-D !
I thought POVers used only binary ?


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From: Stephen
Subject: Re: Spectral locus
Date: 13 Mar 2017 06:54:17
Message: <58c67a59$1@news.povray.org>
On 3/13/2017 10:17 AM, Mr wrote:
> Stephen <mca### [at] aolcom> wrote:

>>>
>>
>>
>> But remember that I have to take my socks off to count past 10. :)
>>
>>
>> --
>>
>> Regards
>>       Stephen
>
> :-D !
> I thought POVers used only binary ?
>

I thought it pretentious to say count past 30. Which is true. Which is 
how I count on my fingers. I can count in binary but it doesn't do my 
arthritis any good. ;)

-- 

Regards
     Stephen


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From: clipka
Subject: Re: Spectral locus
Date: 13 Mar 2017 12:30:51
Message: <58c6c93b$1@news.povray.org>
Am 13.03.2017 um 11:17 schrieb Mr:

>> But remember that I have to take my socks off to count past 10. :)
> 
> :-D !
> I thought POVers used only binary ?

Why, no, of course they don't. POV-Ray only deals in floating-point
numbers, not binary integers ;)


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From: Mike Horvath
Subject: Re: Spectral locus
Date: 13 Mar 2017 15:06:17
Message: <58c6eda9$1@news.povray.org>
So, I want to plot this locus.

This site says it has 4400 data points.

"This data set gives wavelengths every 1.0 nm, along with the associated 
CIE xyz values for the spectral locus of the 1931 CIE chromaticity 
diagram. They are called xyz values here as they are called that in the 
original source, but they are also known as xyY or XYZ values."

https://rdrr.io/cran/SpecHelpers/man/CIExyz.html

I can't figure out how to download them from that site, however. Is 
there another source I can get them from?

Also, I'm guessing the data set will allow me to plot a bunch of points, 
which is great. But how do I create a smooth surface from those points?

Thanks!


Mike


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From: Mike Horvath
Subject: Re: Spectral locus
Date: 13 Mar 2017 15:09:08
Message: <58c6ee54@news.povray.org>
Translator needed:

https://en.wikipedia.org/wiki/Talk:Lab_color_space#CIELAB_images_in_article

The guy I'm talking to here is German, and I don't understand what he's 
talking about. Would someone care to translate for me? Thanks.


Mike


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