10 minutes ago, Biology said:

Yes that's pretty much what this approach does, instead of increasing the spectral resolution, it calculates the best possible approximation for a given amount of spectral samples. Sadly it's not identical to rendering spectrally, because as the light gets attenuated some colors will shift outside the sRGB gamut, but it's still a pretty close approximation.

Thanks for the explanation!

11 minutes ago, Biology said:

Indeed X-Plane 12 was also using the wrong coefficients from Hillaire's paper until very recently, but I contacted them about this approach, which very recently got integrated into the simulator.

Ah, excellent to hear that it's already been corrected there.

I find it interesting that, apparently, both papers got this wrong? I think the pitfalls of only sampling the spectrum at the "centers" of the RGB primaries are pretty well known in computer graphics?

Fingers crossed that you get traction with Asobo on getting this corrected. This would be an easy fix with such a big effect -- but the right person needs to hear about it.

9 minutes ago, martinboehme said:

Thanks for the explanation!

Ah, excellent to hear that it's already been corrected there.

I find it interesting that, apparently, both papers got this wrong? I think the pitfalls of only sampling the spectrum at the "centers" of the RGB primaries are pretty well known in computer graphics?

Fingers crossed that you get traction with Asobo on getting this corrected. This would be an easy fix with such a big effect -- but the right person needs to hear about it.

It was really surprising to me that both papers got it wrong as well, but turns out it's because they both used the same paper as a reference when picking these coefficients (which is what I mentioned as the reference in the thread post), additionally Hillaire's paper cite Bruneton's paper for the coefficients anyway, so I believe they just used the coefficients from Bruneton's paper believing they were accurate.

Indeed it is a really easy fix to implement so I really hope Asobo decides to implement it. The script is MIT-licensed so if they want they can integrate the entire script (instead of just the coefficients) to the simulator as well, which would let them do things like dynamically changing coefficients according to air conditions. Either case, I love sunset / sunrise flying and I really hope we can have this in MSFS.

Edited August 31, 20232 yr by Biology

9 hours ago, scotchegg said:

...most frustratingly, unchanging by latitude / time of year. 

Yes, and I'd like to see adjustments for temperature as well.

They really nailed the sky colors in XP 12, so here’s hoping Asobo can do the same using this information.  Right now it feels as though I’m flying in a painting instead of a dynamic motion picture.

Would love to know who's in charge for the sky/atmospheric effects in MSFS 2020. Perhaps a quicker way to get this valuable piece of information directly to them would be to email one of the main or lead developers and then they can relay it to the proper team.

40 minutes ago, Gilandred said:

They really nailed the sky colors in XP 12, so here’s hoping Asobo can do the same using this information.  Right now it feels as though I’m flying in a painting instead of a dynamic motion picture.

The good thing about physically based rendering is that as long as the equations are physically correct, the results will be the same regardless of where and how they're implemented. Similarly, the coefficients are derived from first principles, therefore they work the same way regardless of where they're implemented and the implementation details. Both MSFS and XP12 use physically based rendering for the atmosphere, so my coefficients should work the exact same way in MSFS that they do in XP12 now, so I'm really optimistic about it being implemented. For instance, the first set of comparisons are from a ShaderToy implementation of Hillaire's paper and the second set is from X-Plane 12, and yet they look the same. The same will very likely be the case for MSFS as well. The main thing that matters is the coefficients being accurate to the real atmosphere, which is what this approach aims to accomplish.

Edited August 31, 20232 yr by Biology

55 minutes ago, Iiari said:

Yes, and I'd like to see adjustments for temperature as well.

... what is implemented "in the other simulator" 😉 since one year, BTW. But psst! 😁

23 minutes ago, flying_carpet said:

... what is implemented "in the other simulator" 😉 since one year, BTW. But psst! 😁

Nope, currently all simulators assume that the atmospheric parameters don't change with temperature. For now LR only implemented the coefficients from ARPC, but maybe in the future they might integrate the full code base which allows for calculating the coefficients for given atmospheric conditions.

If you mean the color temperature adjustment ("Mexico filter") that was implemented to adjust for the lighting condition changes, it was not physically based and looked completely wrong in many cases - so that a lot of developers, including me, asked LR to remove it in the developer Slack, so currently it has very little to no effect.

Edited August 31, 20232 yr by Biology

All this is further over my head than the International Space Station, but it is the most interesting and exciting thing I have heard about for a while.
I am lapping up all of the technical explanations even if I don't understand them - fascinating!
I really hope MS / Asobo can get involved with this and make something good happen.

14 minutes ago, bobcat999 said:

All this is further over my head than the International Space Station, but it is the most interesting and exciting thing I have heard about for a while.
I am lapping up all of the technical explanations even if I don't understand them - fascinating!
I really hope MS / Asobo can get involved with this and make something good happen.

🤣

Join the club !

I feel so so so dumb when I read that technical description, but at the same time so enthusiastic about how even better MFS visuals could look using @Biology's approach that I can only look fwd into it !

It's like women... We will probably never understand them, but they're so fascinating !!!!

Edited August 31, 20232 yr by jcomm

Great work, fella. The comparison screenshots look telling. I've always enjoyed the sunsets in MSFS but now that I see how better they could be then it's a no brainer to get this implemented. I can't help but feel Asobo will turn their nose up at this but I hope not.

I recall an interview with the development team behind FS2004 (so, a couple of years ago 😉) and specifically I think it was an oceanographer and someone else who deals with atmospheric science. They were mentioning how they were approached by the then ACES team to see if they could work with them to help improve the ocean colours and atmosphere behaviour in the then-upcoming simulator. I recall the oceanographer saying that she was very surprised to find herself working on such a project, and the guy responsible for the atmosphere going into great detail about how they modelled it so that you would get appropriate sunsets in different regions of the planet, at different times of the year. It's a shame all of that hard work was lost afterwards.

2 hours ago, Biology said:

which would let them do things like dynamically changing coefficients according to air conditions.

THIS.....

As nice as they look, we really should not be seeing the same tropical sunset all the time in all parts of the world.

@MattNischan Sorry to bother you but you're one of the few people on here I know that works with MS so I'm hoping you can alert the right people to this.

@Biology

Have you tried contacting LM via Support? I had once contacted them with a Question where I 99% expected a "no" - just to be suprised it was a straight-forward "yes" 🙂 
They seem incredibly open to me.

If I would need to bet if LM or Asobo is picking up your incredible Work I'd set my Money on LM ^^

Edited August 31, 20232 yr by Fragtality