Am 13.03.2017 um 20:12 schrieb Mike Horvath:

>> "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."
...
> I'm also assuming the data set will produce a 3D shape. Is that right?

Not really.

What the data set will give you (if you connect the dots) is a line in
2D space, namely the famous CIE "horseshoe".

To get a 3D shape from that, you'll first have to identify what you
really want to plot.

For example, the entire CIExyY colour space would be just an extrusion
of that horseshoe along the Y axis, stretching to positive infinity, as
there is no theoretical limit on brightness (for practical purposes at
any rate): The extruded horseshoe itself would represent the locus of
all theoretically possible monochromatic colours (i.e. colours comprised
of only a single wavelength of light), while the volume it encompasses
would represent the locus of all theoretically possible polychromatic
colours.


On the other hand, the locus of all theoretially possible pigment
colours as illuminated by a particular light source is a much more
complex construct, and creating its shape requires some smart ideas, as
the volume of that shape is effectively a projection from
infinite-dimensional space (each dimension corresponding to the
pigment's reflectivity at a particular wavelength) to 3-dimensional
CIExyY space.

That locus may even differ between light sources with identical CIExyY
whitepoint coordinates, as it depends on the spectrum of the light
source, and different spectra may still result in identical CIExyY
coordinates (see "metamerism").

This is precisely the project for which I did a series of animations a
while ago.

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