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17 May 2024 06:46:15 EDT (-0400)
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From: Mike Horvath
Subject: Re: ChromaDepth
Date: 9 Feb 2018 19:20:26
Message: <5a7e3aca$1@news.povray.org>
On 1/19/2016 12:53 PM, clipka wrote:
> Am 19.01.2016 um 11:41 schrieb Mike Horvath:
> 
>>>> Strictly speaking you can expect depth cues to progress in steps:
>>>> There's one fixed distance corresponding to Red, one corresponding to
>>>> Green, and one corresponding to Blue. All of which will depend on your
>>>> display's primary colours.
>>>>
>>>> Any colour in between just corresponds to a superposition of two
>>>> different depths.
>>>>
>>>> This is especially true if you have a wide-gamut display, i.e. each
>>>> primary covers only a narrow band of wavelengths.
>>>>
>>>
>>> Are you sure? Yellow definitely looks closer than blue, and blends
>>> smoothly into the neighboring colors.
>>>
>>> I *have* noticed a superposition when looking at magenta. It looks both
>>> closer and farther than other colors next to it. It's a hard sensation
>>> to describe.
>>>
>>> Mike
>>
>> Forgot to say that this lead me to believe that spectral colors are the
>> only ones that work properly. Magenta is not a spectral color.
> 
> Which is exactly what I'm saying: In computer displays, anything except
> pure Red, pure Green or pure Blue is /never/ a spectral colour -- it's
> always a superposition of those three basic colours.
> 
> In classic displays, even those are not pure spectral colours -- which
> "blurs" them in depth and thus makes the superposition-nature of
> in-between colours less obvious.
> 
> Wide-gamut displays, on the other hand, require comparatively "pure"
> primary colours to achieve their wide gamut, which "sharpens" them in
> depth, and thus will easily reveal the superposition-nature of
> in-between colours.
> 



I was reading their website the other day, and found their technical page:

http://chromatek.com/what-is-chromadepth/chromadepth-technical-explanation/

According to them, the glasses work on computer displays and printed 
materials too.

Quote: "On a black background, red will appear closest, blue furthest, 
and the other colors will fall in-between according to their place in 
the rainbow (red, orange, yellow, green, blue)."

So, any color should work okay, not just the primaries.


Mike


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From: Mike Horvath
Subject: Re: ChromaDepth
Date: 9 Feb 2018 19:54:50
Message: <5a7e42da$1@news.povray.org>
On 1/17/2016 11:07 PM, Mike Horvath wrote:
> I created the following pigment to be used with ChromaDepth glasses:
> 
>      pigment
>      {
>          gradient vnormalize(Camera_Location - Camera_LookAt) * -1
>          color_map
>          {
>              [0/4 srgb <1,0,0,>]
>              [1/4 srgb <1,1,0,>]
>              [2/4 srgb <0,1,0,>]
>              [3/4 srgb <0,1,1,>]
>              [4/4 srgb <0,0,1,>]
>          }
>          scale vlength(Camera_Location - Camera_LookAt) * 100
>          translate Camera_Location
>      }
> 
> However, the relationship between distance and color is linear in my 
> example. How do I change this so that the hue is based on atan(distance 
> from camera)? Thanks!
> 
> 
> Mike


I am now using a macro.

	#macro MakeChromadepthTexture(CameraLocation, CameraLookAt)
		pigment
		{
			spherical
			color_map
			{
				#for (i, 0, 240, 1)
					[i/240 color rgb CHSL2RGB(<240 - i, 1, 1/2>)]
				#end
			}
		}
	//	finish
	//	{
	//		ambient 1
	//		diffuse 0
	//	}
		scale vlength(CameraLocation - CameraLookAt) * 2
		translate CameraLocation
	#end

But my question is the same. How do I replace `spherical` with 
`atan(distance from camera)`? Possibly, the camera measurements will no 
longer be necessary.

Thanks.


Mike


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From: Mike Horvath
Subject: Re: ChromaDepth
Date: 15 Feb 2018 15:24:18
Message: <5a85ec72$1@news.povray.org>
There is some OpenGL shader code here, but I don't know how to read it.

http://web.engr.oregonstate.edu/~mjb/chromadepth/


Mike


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From: Bald Eagle
Subject: Re: ChromaDepth
Date: 15 Feb 2018 18:45:01
Message: <web.5a861b745228b0755cafe28e0@news.povray.org>
Looks like if you wanted to do that, it's just an HSV-style color map / gradient
in the z-direction.

Just take your object and scale the pattern to that z-size.


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From: Mike Horvath
Subject: Re: ChromaDepth
Date: 16 Feb 2018 21:47:10
Message: <5a8797ae@news.povray.org>
On 2/15/2018 6:44 PM, Bald Eagle wrote:
> Looks like if you wanted to do that, it's just an HSV-style color map / gradient
> in the z-direction.
> 
> Just take your object and scale the pattern to that z-size.
> 
> 

That's what I'm doing, currently.

Mike


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From: Mike Horvath
Subject: Re: ChromaDepth
Date: 17 Feb 2018 00:24:38
Message: <5a87bc96$1@news.povray.org>
I found a paper which proposes an alternate color interpolation for the 
same glasses. Instead of using red, green and blue to encode depth, the 
new method uses red, white and blue.

https://graphics.tudelft.nl/Publications-new/2014/SE14a/

How would I create a pigment that works like this? Thanks.



Mike


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Attachments:
Download 'teaser.jpg' (92 KB)

Preview of image 'teaser.jpg'
teaser.jpg


 

From: Thomas de Groot
Subject: Re: ChromaDepth
Date: 17 Feb 2018 02:55:11
Message: <5a87dfdf$1@news.povray.org>
On 17-2-2018 6:24, Mike Horvath wrote:
> I found a paper which proposes an alternate color interpolation for the 
> same glasses. Instead of using red, green and blue to encode depth, the 
> new method uses red, white and blue.
> 
> https://graphics.tudelft.nl/Publications-new/2014/SE14a/
> 
> How would I create a pigment that works like this? Thanks.
> 
> 

Maybe this?

pigment {
   gradient z
   color_map {
     [0.00 Red]
     [0.50 White]
     [1.00 Blue]
   }
   scale <1, 1, DepthOfScene>
}

Maybe you have to switch Blue and Red. Not sure.

-- 
Thomas


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From: Mike Horvath
Subject: Re: ChromaDepth
Date: 17 Feb 2018 05:52:06
Message: <5a880956$1@news.povray.org>
On 2/17/2018 2:55 AM, Thomas de Groot wrote:
> On 17-2-2018 6:24, Mike Horvath wrote:
>> I found a paper which proposes an alternate color interpolation for 
>> the same glasses. Instead of using red, green and blue to encode 
>> depth, the new method uses red, white and blue.
>>
>> https://graphics.tudelft.nl/Publications-new/2014/SE14a/
>>
>> How would I create a pigment that works like this? Thanks.
>>
>>
> 
> Maybe this?
> 
> pigment {
>    gradient z
>    color_map {
>      [0.00 Red]
>      [0.50 White]
>      [1.00 Blue]
>    }
>    scale <1, 1, DepthOfScene>
> }
> 
> Maybe you have to switch Blue and Red. Not sure.
> 


Would spherical be better than gradient? That's what I've been using.


Mike


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From: Thomas de Groot
Subject: Re: ChromaDepth
Date: 17 Feb 2018 07:24:49
Message: <5a881f11$1@news.povray.org>
On 17-2-2018 11:52, Mike Horvath wrote:
> On 2/17/2018 2:55 AM, Thomas de Groot wrote:
>> On 17-2-2018 6:24, Mike Horvath wrote:
>>> I found a paper which proposes an alternate color interpolation for 
>>> the same glasses. Instead of using red, green and blue to encode 
>>> depth, the new method uses red, white and blue.
>>>
>>> https://graphics.tudelft.nl/Publications-new/2014/SE14a/
>>>
>>> How would I create a pigment that works like this? Thanks.
>>>
>>>
>>
>> Maybe this?
>>
>> pigment {
>>    gradient z
>>    color_map {
>>      [0.00 Red]
>>      [0.50 White]
>>      [1.00 Blue]
>>    }
>>    scale <1, 1, DepthOfScene>
>> }
>>
>> Maybe you have to switch Blue and Red. Not sure.
>>
> 
> 
> Would spherical be better than gradient? That's what I've been using.
> 
> 

Yes indeed. See this test file I found in my archives.


-- 
Thomas


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Attachments:
Download 'tdg_depth_map.pov.txt' (3 KB)

From: Mike Horvath
Subject: Re: ChromaDepth
Date: 21 Feb 2018 03:31:33
Message: <5a8d2e65$1@news.povray.org>
On 1/16/2016 12:53 AM, Mike Horvath wrote:
> http://chromatek.com/what-is-chromadepth/design-guide-2/
> 
> I've been reading their documentation, but I can't figure out if the 
> progression from near to far is linear or not. I.e. is blue just as far 
> from green as green is from blue? Or is it exponential? I plan on doing 
> some experiments in the near future, but I can't figure out for sure 
> whether this is the case.
> 
> 
> Mike

Okay, I asked on Stack Exchange, but no one wanted to bite and the topic 
got closed. No feedback as always.

https://physics.stackexchange.com/questions/385827/chromadepth-glasses


Mike


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