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Upcoming Events #cal-summary

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Open Shading Language discussion list Upcoming Events

OSL TSC meeting ( every other week )

When:
Thursday, 4 February 2021, 2:00pm to 3:00pm
(GMT-08:00) America/Los Angeles

Where:
https://zoom.us/j/100511909

Organizer: Chris Kulla ckulla@...

Details:

Every other week meeting of the OSL TSC.

Meeting Agenda / Notes: https://docs.google.com/document/d/1yf0bG6eoE2EvKZBNZX3nskdTvu99ADTDTNOknCDJd1I/

Confirm this meeting invite is still valid by finding the meeting at https://lists.aswf.io/calendar.

Join Zoom Meeting https://zoom.us/j/100511909

Meeting ID: 100 511 909

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OSL TSC meeting ( every other week )

When:
Thursday, 18 February 2021, 2:00pm to 3:00pm
(GMT-08:00) America/Los Angeles

Where:
https://zoom.us/j/100511909

Organizer: Chris Kulla ckulla@...

Details:

Every other week meeting of the OSL TSC.

Meeting Agenda / Notes: https://docs.google.com/document/d/1yf0bG6eoE2EvKZBNZX3nskdTvu99ADTDTNOknCDJd1I/

Confirm this meeting invite is still valid by finding the meeting at https://lists.aswf.io/calendar.

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Meeting ID: 100 511 909

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OSL TSC meeting ( every other week ) - Thu, 01/21/2021 #cal-notice

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OSL TSC meeting ( every other week )

When:
Thursday, 21 January 2021
2:00pm to 3:00pm
(GMT-08:00) America/Los Angeles

Where:
https://zoom.us/j/100511909

Organizer:
ckulla@...

Description:

Every other week meeting of the OSL TSC.

Meeting Agenda / Notes: https://docs.google.com/document/d/1yf0bG6eoE2EvKZBNZX3nskdTvu99ADTDTNOknCDJd1I/

Confirm this meeting invite is still valid by finding the meeting at https://lists.aswf.io/calendar.

Join Zoom Meeting https://zoom.us/j/100511909

Meeting ID: 100 511 909

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OSL TSC meeting ( every other week ) - Thu, 01/21/2021 2:00pm-3:00pm #cal-reminder

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Reminder: OSL TSC meeting ( every other week )

When: Thursday, 21 January 2021, 2:00pm to 3:00pm, (GMT-08:00) America/Los Angeles

Where:https://zoom.us/j/100511909

View Event

Organizer: Chris Kulla ckulla@...

Description:

Every other week meeting of the OSL TSC.

Meeting Agenda / Notes: https://docs.google.com/document/d/1yf0bG6eoE2EvKZBNZX3nskdTvu99ADTDTNOknCDJd1I/

Confirm this meeting invite is still valid by finding the meeting at https://lists.aswf.io/calendar.

Join Zoom Meeting https://zoom.us/j/100511909

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OSL TSC meeting ( every other week ) - Thu, 01/21/2021 2:00pm-3:00pm #cal-reminder

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Reminder: OSL TSC meeting ( every other week )

When: Thursday, 21 January 2021, 2:00pm to 3:00pm, (GMT-08:00) America/Los Angeles

Where:https://zoom.us/j/100511909

View Event

Organizer: Chris Kulla ckulla@...

Description:

Every other week meeting of the OSL TSC.

Meeting Agenda / Notes: https://docs.google.com/document/d/1yf0bG6eoE2EvKZBNZX3nskdTvu99ADTDTNOknCDJd1I/

Confirm this meeting invite is still valid by finding the meeting at https://lists.aswf.io/calendar.

Join Zoom Meeting https://zoom.us/j/100511909

Meeting ID: 100 511 909

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OSL TSC meeting ( every other week ) - Thu, 01/21/2021 2:00pm-3:00pm #cal-reminder

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Reminder: OSL TSC meeting ( every other week )

When: Thursday, 21 January 2021, 2:00pm to 3:00pm, (GMT-08:00) America/Los Angeles

Where:https://zoom.us/j/100511909

View Event

Organizer: Chris Kulla ckulla@...

Description:

Every other week meeting of the OSL TSC.

Meeting Agenda / Notes: https://docs.google.com/document/d/1yf0bG6eoE2EvKZBNZX3nskdTvu99ADTDTNOknCDJd1I/

Confirm this meeting invite is still valid by finding the meeting at https://lists.aswf.io/calendar.

Join Zoom Meeting https://zoom.us/j/100511909

Meeting ID: 100 511 909

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Upcoming Events #cal-summary

osl-dev@lists.aswf.io Calendar <osl-dev@...>
 

Open Shading Language discussion list Upcoming Events

OSL TSC meeting ( every other week )

When:
Thursday, 21 January 2021, 2:00pm to 3:00pm
(GMT-08:00) America/Los Angeles

Where:
https://zoom.us/j/100511909

Organizer: Chris Kulla ckulla@...

Details:

Every other week meeting of the OSL TSC.

Meeting Agenda / Notes: https://docs.google.com/document/d/1yf0bG6eoE2EvKZBNZX3nskdTvu99ADTDTNOknCDJd1I/

Confirm this meeting invite is still valid by finding the meeting at https://lists.aswf.io/calendar.

Join Zoom Meeting https://zoom.us/j/100511909

Meeting ID: 100 511 909

One tap mobile +16465588656,,100511909# US (New York) +13126266799,,100511909# US (Chicago)

Dial by your location +1 646 558 8656 US (New York) +1 312 626 6799 US (Chicago) +1 669 900 6833 US (San Jose) +1 253 215 8782 US +1 301 715 8592 US +1 346 248 7799 US (Houston) 877 369 0926 US Toll-free 855 880 1246 US Toll-free +1 587 328 1099 Canada +1 647 374 4685 Canada +1 647 558 0588 Canada +1 778 907 2071 Canada +1 438 809 7799 Canada 855 703 8985 Canada Toll-free Meeting ID: 100 511 909 Find your local number: https://zoom.us/u/acBVrM6HWR

View Event


OSL TSC meeting ( every other week )

When:
Thursday, 4 February 2021, 2:00pm to 3:00pm
(GMT-08:00) America/Los Angeles

Where:
https://zoom.us/j/100511909

Organizer: Chris Kulla ckulla@...

Details:

Every other week meeting of the OSL TSC.

Meeting Agenda / Notes: https://docs.google.com/document/d/1yf0bG6eoE2EvKZBNZX3nskdTvu99ADTDTNOknCDJd1I/

Confirm this meeting invite is still valid by finding the meeting at https://lists.aswf.io/calendar.

Join Zoom Meeting https://zoom.us/j/100511909

Meeting ID: 100 511 909

One tap mobile +16465588656,,100511909# US (New York) +13126266799,,100511909# US (Chicago)

Dial by your location +1 646 558 8656 US (New York) +1 312 626 6799 US (Chicago) +1 669 900 6833 US (San Jose) +1 253 215 8782 US +1 301 715 8592 US +1 346 248 7799 US (Houston) 877 369 0926 US Toll-free 855 880 1246 US Toll-free +1 587 328 1099 Canada +1 647 374 4685 Canada +1 647 558 0588 Canada +1 778 907 2071 Canada +1 438 809 7799 Canada 855 703 8985 Canada Toll-free Meeting ID: 100 511 909 Find your local number: https://zoom.us/u/acBVrM6HWR

View Event


OSL TSC meeting ( every other week ) - Thu, 01/21/2021 2:00pm-3:00pm #cal-reminder

osl-dev@lists.aswf.io Calendar <osl-dev@...>
 

Reminder: OSL TSC meeting ( every other week )

When: Thursday, 21 January 2021, 2:00pm to 3:00pm, (GMT-08:00) America/Los Angeles

Where:https://zoom.us/j/100511909

View Event

Organizer: Chris Kulla ckulla@...

Description:

Every other week meeting of the OSL TSC.

Meeting Agenda / Notes: https://docs.google.com/document/d/1yf0bG6eoE2EvKZBNZX3nskdTvu99ADTDTNOknCDJd1I/

Confirm this meeting invite is still valid by finding the meeting at https://lists.aswf.io/calendar.

Join Zoom Meeting https://zoom.us/j/100511909

Meeting ID: 100 511 909

One tap mobile +16465588656,,100511909# US (New York) +13126266799,,100511909# US (Chicago)

Dial by your location +1 646 558 8656 US (New York) +1 312 626 6799 US (Chicago) +1 669 900 6833 US (San Jose) +1 253 215 8782 US +1 301 715 8592 US +1 346 248 7799 US (Houston) 877 369 0926 US Toll-free 855 880 1246 US Toll-free +1 587 328 1099 Canada +1 647 374 4685 Canada +1 647 558 0588 Canada +1 778 907 2071 Canada +1 438 809 7799 Canada 855 703 8985 Canada Toll-free Meeting ID: 100 511 909 Find your local number: https://zoom.us/u/acBVrM6HWR


Re: OSL Docs

Mitch Prater
 

FYI, we'll be moving the osl-doc repo contents to the osl master branch instead. This will keep the licensing consistent with the OSL project itself and avoid any cumbersome issues that might arise from porting them from another repo.

These new files will be staged in a new `doc` directory.

Further discourse about OSL Documentation may be carried out under OSL Discussions: https://github.com/imageworks/OpenShadingLanguage/discussions


Re: OSL Docs

Larry Gritz
 

Yes, we use CC BY 4.0 for documentation, BSD-3-Clause for code.



On Jan 12, 2021, at 7:30 PM, Chris Burrows <cburrows@...> wrote:

Hi all-

I'm still working on getting approval from my employer to contribute documentation. Will the documentation be under the same license as OSL itself? I'm not familiar with the details but someone on our team raised as a data point some of the other OSS projects use a different Creative Commons license for their documentation.

Thanks,
cb


On Sun, Jan 10, 2021 at 11:04 AM Larry Gritz <lg@...> wrote:
This is great, I'm thrilled to see you moving forward on these.

Note that we already have "contributing" and "install" documents in the current repo, and it's fine to just directly propose changes there. But if you are just intending osl-doc to be a staging area, someplace where you can temporarily start fresh without any distraction by or temptation to keep the existing docs, then that's fine, and when you feel they're ready, they can be moved back.

In the long run, any docs that are tightly coupled to a particular OSL version (API docs and installation docs, for example) probably belong in the main repo, as having them in a separate project just invites confusion or errors that result from somebody not having exactly the right corresponding versions of the two projects. The argument may be stronger for larger and not-tied-to-specific-versions documentation projects to be separate from the main code repo (the web site, or an extensive OSL shading tutorial might be good examples). These are all things where we can defer until farther down the road discussion of the merits of exactly where they should permanently live.

If you need a staging area, or eventually even a permanent second repository for things that should not be part of the main code repo, it is not necessary for you to do it in your own personal account. We can create secondary/scratch repos under AcademySoftwareFoundation, and there's no reason (especially for new material) to wait until we move the main repo from imageworks to ASWF (which will happen, hopefully, in the next few weeks anyway). Just give the word, and we can make you a new repo.

I also just gave you write permissions on the current repo (the imageworks one), so if you need to, you should feel free to make separate branches where you can work on in-tree docs (and even accept PRs into those branches only) without polluting master quite yet.

Any secondary repository should be populated with the OSL license files and notices (BSD 3-clause for code, Creative Commons CC BY 4.0 for docs) at the very least. You don't want to get to the point where you've collected contributions from a bunch of people, and then when it's time to re-integrate it into the main project, we can't do it because it's not legally clear what licenses it's covered by and you might need to track down every last person who contributed any bit and get their explicit ok to relicense it. Huge PITA.

-- lg


On Jan 8, 2021, at 1:50 PM, Mitch Prater <mprater@...> wrote:

Hi All,

I've created a temporary github project/repo for collecting any OSL documentation we're working on: https://github.com/mprater/osl-doc

I've never managed an on-line or collaborative documentation project before, so this is the best I could come up with. If there's a better way to go about this please let me know. I've initialized the repository with the work we've already done.

Please consider contributing useful information you may have.

Thanks, mitch

--
Larry Gritz








-- 
============
A collection of locations and attributes
He/him

--
Larry Gritz





Re: OSL Docs

Chris Burrows
 

Hi all-

I'm still working on getting approval from my employer to contribute documentation. Will the documentation be under the same license as OSL itself? I'm not familiar with the details but someone on our team raised as a data point some of the other OSS projects use a different Creative Commons license for their documentation.

Thanks,
cb


On Sun, Jan 10, 2021 at 11:04 AM Larry Gritz <lg@...> wrote:
This is great, I'm thrilled to see you moving forward on these.

Note that we already have "contributing" and "install" documents in the current repo, and it's fine to just directly propose changes there. But if you are just intending osl-doc to be a staging area, someplace where you can temporarily start fresh without any distraction by or temptation to keep the existing docs, then that's fine, and when you feel they're ready, they can be moved back.

In the long run, any docs that are tightly coupled to a particular OSL version (API docs and installation docs, for example) probably belong in the main repo, as having them in a separate project just invites confusion or errors that result from somebody not having exactly the right corresponding versions of the two projects. The argument may be stronger for larger and not-tied-to-specific-versions documentation projects to be separate from the main code repo (the web site, or an extensive OSL shading tutorial might be good examples). These are all things where we can defer until farther down the road discussion of the merits of exactly where they should permanently live.

If you need a staging area, or eventually even a permanent second repository for things that should not be part of the main code repo, it is not necessary for you to do it in your own personal account. We can create secondary/scratch repos under AcademySoftwareFoundation, and there's no reason (especially for new material) to wait until we move the main repo from imageworks to ASWF (which will happen, hopefully, in the next few weeks anyway). Just give the word, and we can make you a new repo.

I also just gave you write permissions on the current repo (the imageworks one), so if you need to, you should feel free to make separate branches where you can work on in-tree docs (and even accept PRs into those branches only) without polluting master quite yet.

Any secondary repository should be populated with the OSL license files and notices (BSD 3-clause for code, Creative Commons CC BY 4.0 for docs) at the very least. You don't want to get to the point where you've collected contributions from a bunch of people, and then when it's time to re-integrate it into the main project, we can't do it because it's not legally clear what licenses it's covered by and you might need to track down every last person who contributed any bit and get their explicit ok to relicense it. Huge PITA.

-- lg


On Jan 8, 2021, at 1:50 PM, Mitch Prater <mprater@...> wrote:

Hi All,

I've created a temporary github project/repo for collecting any OSL documentation we're working on: https://github.com/mprater/osl-doc

I've never managed an on-line or collaborative documentation project before, so this is the best I could come up with. If there's a better way to go about this please let me know. I've initialized the repository with the work we've already done.

Please consider contributing useful information you may have.

Thanks, mitch

--
Larry Gritz






--
============
A collection of locations and attributes
He/him


Trying GitHub Discussions beta

Larry Gritz
 

Without committing to whether we will keep this in the long term, or exactly where to draw the line is between Discussions and the email list, I've opened the new GitHub Discussions feature so that we can poke around and experiment with it.

https://github.com/imageworks/OpenShadingLanguage/discussions/1323

Use the "watch" button on the repo page to subscribe to the discussions if you want.

--
Larry Gritz
lg@larrygritz.com


ASWF survey

Larry Gritz
 

Survey seeking valuable feedback for ASWF projects:

https://www.surveymonkey.com/r/ASWF


--
Larry Gritz
lg@larrygritz.com


Re: blackbody and daylight functions

chrisbrejon@...
 

I'll just put your answer here because it made "click" in my head when I read it :

If you’re using a blackbody for a light colour it should be because you’re trying to simulate an incandescent of that temperature. 
Blackbody colours have precisely nothing to do with the colour of the sky. As others have mentioned the fact that literature refers to colours as “sky blue” is an attempt at classification.

Thanks again everyone, you rock !

Chris


Re: blackbody and daylight functions

Anders Langlands
 

Ah only just realised I didn’t reply-all! Thiago and Larry have said the same thing as I did anyway :)

On Tue, 12 Jan 2021 at 09:06, <chrisbrejon@...> wrote:
Thanks a lot everyone! I understand much better the topic now. ;-)
Anders Langlands has also been kind enough to reply and help me.

I often say that studying colour is a fight against my own beliefs and what I have learned these past 15 years.
Your answers make definitely sense and I apologize for not having understood your explanations earlier.

Have a good day all ! That's really much appreciated !!!

Chris


Re: blackbody and daylight functions

Larry Gritz
 

Color science is an area where I truly feel that the more I learn about it, the more I realize I didn't really understand and have been making embarrassing oversimplifications all along. Also the more I learn, the more I appreciate having a capable dedicated color scientist on staff because my own knowledge just barely scratches the surface.


On Jan 11, 2021, at 12:06 PM, chrisbrejon@... wrote:

Thanks a lot everyone! I understand much better the topic now. ;-)
Anders Langlands has also been kind enough to reply and help me.

I often say that studying colour is a fight against my own beliefs and what I have learned these past 15 years.
Your answers make definitely sense and I apologize for not having understood your explanations earlier.

Have a good day all ! That's really much appreciated !!!

Chris

--
Larry Gritz





Re: blackbody and daylight functions

chrisbrejon@...
 

Thanks a lot everyone! I understand much better the topic now. ;-)
Anders Langlands has also been kind enough to reply and help me.

I often say that studying colour is a fight against my own beliefs and what I have learned these past 15 years.
Your answers make definitely sense and I apologize for not having understood your explanations earlier.

Have a good day all ! That's really much appreciated !!!

Chris


Re: blackbody and daylight functions

Larry Gritz
 

Ah, I see, sorry for assuming you were poking around at the wrong thing.

The blackbody function is good for figuring out the color of something that is purely an emissive warm body, no more and no less. An incandescent filament, a glowing hot piece of metal, molten lava, etc. There's no particular reason to think this function would give you a good approximation to daylight sky, which is not a blackbody phenomenon.

If there is another function that gives the range of plausible overall daylight colors given a 1D input (which we can call "temperature", but doesn't relate quite as directly as a blackbody spectrum would), and this is useful in shaders for generating light colors, then by all means, we can add a new function to the spec. I think the implementation could probably be a lot simpler than what we've done for blackbody -- you may be able to implement it very simply in OSL itself with a couple of spline() calls with a fairly short array of values and get an adequate approximation to the desired function.

-- lg


On Jan 11, 2021, at 11:16 AM, chrisbrejon@... wrote:

Totally ! ;-)

Our studio is following the same path most studios are : we have an Hosek sky implementation since 2015 (if I recall correctly).
And we are indeed looking at Sebastien Hilaire's work for our next generation Skylight.

Sorry for repeating myself but my question was really about the temperature function for, let's say, an area light.
An artist may think : let's use a kelvin temperature of 20 000 to get a blue sky color on a rim. And because most render engines
rely on black body tables, the blue color will actually look quite purple (to me). Hence my question...

Of course, we would not want a "flat" color on a EnvLight but on an area or spot light to simulate a rim or a top light. A bit like this :
<dummyfile.0.part>

I guess my point is : in many renderer's documentation, you may read that black body temperatures above 15 000 would give you a sky blue color...
When actually it is not really a goof fit imo.

Sorry for the confusion, I don't mean to bother you guys. ;-)
Once again, your answers are much appreciated !

Chris

--
Larry Gritz





Re: blackbody and daylight functions

Thiago Ize
 

Blackbody works only for incandescent lights. Make it 20000K and it should look like what you posted (blue with hints of red). It'll still have red in it because all that changed from the hotter light is that correspondingly more blue was added, but red was never removed. This is why you can't get a pure blue. What you can do is drown out the red by having huge amounts of blue. Even hotter temps will emit lots of UV, but since we don't see that we'll just see it as more blue. Also, that's a crazy hot surface and probably not realistic...

In the real world filters would be applied to incandescent lights to filter out the red so we see it as more blue. Or LEDs or other non-incandescent lights are used which can generate specific frequencies of light.

Take a look at the graph in https://astronomy.swin.edu.au/cosmos/b/blackbody+radiation which shows how at 700nm the blue star is still outputting more red than the red star.

To summarize, blackbody for lights is for incandescent lights without filters. Anything else and the renderer should allow users to input colors in some other fashion, such as RGB.


On Mon, Jan 11, 2021 at 12:16 PM <chrisbrejon@...> wrote:
Totally ! ;-)

Our studio is following the same path most studios are : we have an Hosek sky implementation since 2015 (if I recall correctly).
And we are indeed looking at Sebastien Hilaire's work for our next generation Skylight.

Sorry for repeating myself but my question was really about the temperature function for, let's say, an area light.
An artist may think : let's use a kelvin temperature of 20 000 to get a blue sky color on a rim. And because most render engines
rely on black body tables, the blue color will actually look quite purple (to me). Hence my question...

Of course, we would not want a "flat" color on a EnvLight but on an area or spot light to simulate a rim or a top light. A bit like this :


I guess my point is : in many renderer's documentation, you may read that black body temperatures above 15 000 would give you a sky blue color...
When actually it is not really a goof fit imo.

Sorry for the confusion, I don't mean to bother you guys. ;-)
Once again, your answers are much appreciated !

Chris


Re: blackbody and daylight functions

chrisbrejon@...
 

Totally ! ;-)

Our studio is following the same path most studios are : we have an Hosek sky implementation since 2015 (if I recall correctly).
And we are indeed looking at Sebastien Hilaire's work for our next generation Skylight.

Sorry for repeating myself but my question was really about the temperature function for, let's say, an area light.
An artist may think : let's use a kelvin temperature of 20 000 to get a blue sky color on a rim. And because most render engines
rely on black body tables, the blue color will actually look quite purple (to me). Hence my question...

Of course, we would not want a "flat" color on a EnvLight but on an area or spot light to simulate a rim or a top light. A bit like this :


I guess my point is : in many renderer's documentation, you may read that black body temperatures above 15 000 would give you a sky blue color...
When actually it is not really a goof fit imo.

Sorry for the confusion, I don't mean to bother you guys. ;-)
Once again, your answers are much appreciated !

Chris


Re: blackbody and daylight functions

Larry Gritz
 

The "sky color by temperature" function is just a model that sort of relates color temperature to a plausible overall color of the sky integrated over all directions. In a rendering context, I'm not sure how or why you would use this. You certainly wouldn't want the sky to be this color, because it would be the same in all directions. What you really want is the correct directional radiance function.

Hosek/Wilkie "An Analytic Model for Full Spectral Sky-Dome Radiance" from SIGGRAPH 2012 is usually the go-to on this topic. That paper, and some other work from the same researchers, can be found here: https://cgg.mff.cuni.cz/projects/SkylightModelling/  I think most studios have an in-house shader that implements this paper or some fairly close variant. I believe there are open source implementations in various shading language already out there to be found with a little googling.

The state of the art is likely this year's EGSR 2020 paper from Sebastien Hillaire, "A Scalable and Production Ready Sky and Atmosphere Rendering Technique," which describes what's implemented in Unreal Engine. Here's the paper: https://diglib.eg.org/bitstream/handle/10.1111/cgf14050/v39i4pp013-022.pdf and here's the code (MIT licensed): https://github.com/sebh/UnrealEngineSkyAtmosphere

-- lg



On Jan 11, 2021, at 5:40 AM, chrisbrejon@... wrote:

And just for the record, it looks like there is a CIE standard for sky values :

This web app generates sky luminance and radiance distributions using the updated Perez All-Weather Sky model, as defined in ISO 15469:2004(E) and CIE S 011/E:2003. You can dynamically adjust each of the Perez sky coefficients individually, choose any of the 16 CIE Standard General Skies, set your own direct and diffuse illuminance/irradiance values, or use annual hourly weather data for dynamic simulations or cumulative sky distributions. It also provides a range of different sky subdivision techniques and resolutions, including Tregenza’s 145 patch sky and Reinhart’s extensions.

The Commission Internationale de l’Éclairage (CIE) has defined a set of 15 standard sky types for modelling the radiance/luminance distribution under a wide range of weather conditions from overcast to cloudless, and with or without direct sunlight. The 16th varient corresponds to a much simpler mathematical model for overcast skies defined and used by CIE prior to this standard.

The various sky types are generated using different values for each of the 5 sky coefficients shown in the panel above.

Quite cool !  ;-)

--
Larry Gritz




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