Am 11.12.2016 um 01:12 schrieb clipka:
> Am 11.12.2016 um 00:09 schrieb Mike Horvath:
>> On 11/29/2016 10:56 PM, clipka wrote:
>>> Gamut of all theoretically possible surface colours, under D65 (noon
>>> daylight) illumination, in CIE 1931 xyY space.
>>>
>>
>> How did you generate the meshes?
> 
> "It's complicated."

Oh, and of course for the sake of parsing performance I used `#write` to
generate the mesh as a POV-Ray include file, safeguarding the code using
`#if (file_exists(...))`, and then used `#include` to load it.

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On 11/29/2016 10:56 PM, clipka wrote:
> Gamut of all theoretically possible surface colours, under D65 (noon
> daylight) illumination, in CIE 1931 xyY space.
>

Did you use radiosity or emission? I am trying to render the same shape 
but in my scene the shadows are not well defined.


Mike

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Am 19.03.2017 um 03:11 schrieb Mike Horvath:
> On 11/29/2016 10:56 PM, clipka wrote:
>> Gamut of all theoretically possible surface colours, under D65 (noon
>> daylight) illumination, in CIE 1931 xyY space.
>>
> 
> Did you use radiosity or emission? I am trying to render the same shape
> but in my scene the shadows are not well defined.

Radiosity, most surely. I can't stand the look of scenes that don't use it.

I did need some twiddling of the radiosity settings to make it look good
though. I guess I did specify a rather low "maximum_reuse" setting.

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Am 20.03.2017 um 02:21 schrieb Mike Horvath:
> On 11/29/2016 10:56 PM, clipka wrote:
>> Gamut of all theoretically possible surface colours, under D65 (noon
>> daylight) illumination, in CIE 1931 xyY space.
>>
> 
> Here's my version, thanks to clipka and Bruce Lindbloom.

That looks about right now.

You seem to have a gap between the shape and the "black pane" though,
which is particularly noticeable in the yellow and green regions.

I'd therefore recommend investing a bit of extra work to make the shape
extend to the black point -- or, more precisely, the locus of
infinitesimally dark spectral colours.

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On 3/20/2017 8:21 AM, clipka wrote:
> Am 20.03.2017 um 02:21 schrieb Mike Horvath:
>> On 11/29/2016 10:56 PM, clipka wrote:
>>> Gamut of all theoretically possible surface colours, under D65 (noon
>>> daylight) illumination, in CIE 1931 xyY space.
>>>
>>
>> Here's my version, thanks to clipka and Bruce Lindbloom.
>
> That looks about right now.
>
> You seem to have a gap between the shape and the "black pane" though,
> which is particularly noticeable in the yellow and green regions.
>
> I'd therefore recommend investing a bit of extra work to make the shape
> extend to the black point -- or, more precisely, the locus of
> infinitesimally dark spectral colours.
>

I'm not sure what to do with black. It's degenerate in xyY space, isn't 
it? I get divide-by-zero errors when converting from XYZ.


Mike

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Am 20.03.2017 um 14:52 schrieb Mike Horvath:
> On 3/20/2017 8:21 AM, clipka wrote:
>> Am 20.03.2017 um 02:21 schrieb Mike Horvath:
>>> On 11/29/2016 10:56 PM, clipka wrote:
>>>> Gamut of all theoretically possible surface colours, under D65 (noon
>>>> daylight) illumination, in CIE 1931 xyY space.
>>>>
>>>
>>> Here's my version, thanks to clipka and Bruce Lindbloom.
>>
>> That looks about right now.
>>
>> You seem to have a gap between the shape and the "black pane" though,
>> which is particularly noticeable in the yellow and green regions.
>>
>> I'd therefore recommend investing a bit of extra work to make the shape
>> extend to the black point -- or, more precisely, the locus of
>> infinitesimally dark spectral colours.
>>
> 
> I'm not sure what to do with black. It's degenerate in xyY space, isn't
> it? I get divide-by-zero errors when converting from XYZ.

That's why you need to go for infinitesimally dark colours instead: Set
all wavelengths to zero, except for a single wavelength which you set to
a darn small power like, say, 1e-3.

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On 3/20/2017 11:48 AM, clipka wrote:
> Am 20.03.2017 um 14:52 schrieb Mike Horvath:
>> On 3/20/2017 8:21 AM, clipka wrote:
>>> Am 20.03.2017 um 02:21 schrieb Mike Horvath:
>>>> On 11/29/2016 10:56 PM, clipka wrote:
>>>>> Gamut of all theoretically possible surface colours, under D65 (noon
>>>>> daylight) illumination, in CIE 1931 xyY space.
>>>>>
>>>>
>>>> Here's my version, thanks to clipka and Bruce Lindbloom.
>>>
>>> That looks about right now.
>>>
>>> You seem to have a gap between the shape and the "black pane" though,
>>> which is particularly noticeable in the yellow and green regions.
>>>
>>> I'd therefore recommend investing a bit of extra work to make the shape
>>> extend to the black point -- or, more precisely, the locus of
>>> infinitesimally dark spectral colours.
>>>
>>
>> I'm not sure what to do with black. It's degenerate in xyY space, isn't
>> it? I get divide-by-zero errors when converting from XYZ.
>
> That's why you need to go for infinitesimally dark colours instead: Set
> all wavelengths to zero, except for a single wavelength which you set to
> a darn small power like, say, 1e-3.
>

I ended up just replacing that bottom row with the standard 2D xy 
chromaticity diagram, but colored black.

Thanks for catching the issue! I would not have noticed it myself.


Mike

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