Smaller sun for DCS World

This modification will make the sun smaller in size.

I have also bundled my modified sky.fx for enhanced atmospheric and terrain lighting (a spinoff from this thread http://forums.eagle.ru/showthread.php?t=90290)

EDIT: PeterP has created a definitive version available here http://forums.eagle.ru/showthread.php?p=1526362&posted=1#post1526362

Nah, that looks about spot on.

Yes! Great stuff, mate. Will download and check. Also, I'll be able to check compatibility with Diveplane's small sun flare mod.

Ok, so it seems that the sun flare files are now bigger than the sun (understandably, perhaps). They look ok in your pics though, Mustang. Did you modify them?

No they're still the stock ray textures in those screenshots.

Ok, then, oddly, the stock textures seem to resize to the sun? Pretty sure diveplane's don't.

Regarding the size: the sun subtends about a 0.2 deg^2 solid angle (0.5 deg radius) seen from earth.

That means we can find the radius the solar disc should have in pixels: 1/720 * 360 deg/F * Rv, where F is the FOV in degrees and Rv is the vertical resolution of the screen in pixels.

I suppose we should do this at the default zoom, cause it scales oddly with FOV right?

No they're still the stock ray textures in those screenshots.

Just checked it out on a late morning mission and if you very slowly move the sun's disk on to the edge of the FOV of the monitor, the flare disappears momentarily, and you can see the disk you've made, directly. And is is much smaller than that remaining enormous standard flare still makes it appear.

So you have the size of the disk 'right', but the standard uber-radiant flare needs to be toned down, as it is still making the sun look too-big, when it's higher and brighter in the sky.

You have the colour right at that point though Mustang - white. It should only get yellow progressively and then reddish tinged, as it passes at lower and lower angles through the atmosphere, and blue wavelengths are not present in the transmitted light any more.

Just checked it out on a late morning mission and if you very slowly move the sun's disk on to the edge of the FOV of the monitor, the flare disappears momentarily, and you can see the disk you've made, directly. And is is much smaller than that remaining enormous standard flare still makes it appear.

 

So you have the size of the disk 'right', but the standard uber-radiant flare needs to be toned down, as it is still making the sun look too-big, when it's higher and brighter in the sky.

 

You have the colour right at that point though Mustang - white. It should only get yellow progressively and then reddish tinged, as it passes at lower and lower angles through the atmosphere, and blue wavelengths are not present in the transmitted light any more.

Yeah thats it, i've set the size now we just need a good texture guy to make it fit to scale.

Yeah thats it, i've set the size now we just need a good texture guy to make it fit to scale.

I should have said:

It should only get yellow progressively, then more orange at lower angles, then slightly reddish tinged at the very lowest angle, as it passes at lower and lower angles through the atmosphere, and blue wavelengths are not present in the transmitted light any more.

WOW very nice Mustang. I like that sun much better! Looks closer to the real thing.

Nice job Stang!

Is there any way you could shrink it even more? A little over a year ago, I measured the sun in DCS to be 3 degrees across, six times larger than it is in real life, but maybe they've changed it since then.

If the sun were that big IRL, Earth's surface would be a sea of lava :)

I am curious if this smaller sun mod will work with diveplanes sunflare mod? Or are they two separate deals?

Is there any way you could shrink it even more? A little over a year ago, I measured the sun in DCS to be 3 degrees across, six times larger than it is in real life, but maybe they've changed it since then.

I'm not an expert regarding such things but I think calculating the size of the sun's disk is way more complicated. Especially if the sun is low, refraction and reflection in the atmosphere will make it look bigger than it actually is.

Maybe I will take a look at the sun with solar eclipse goggles this evening:smartass:

I'm not an expert regarding such things but I think calculating the size of the sun's disk is way more complicated. Especially if the sun is low, refraction and reflection in the atmosphere will make it look bigger than it actually is. Maybe I will take a look at the sun with solar eclipse goggles this evening:smartass:

If the nominal size of the disk remains about the same fraction of the 360 degrees circumference of the horizon line on most days, then Speed is giving the right basis for comparison, for this purpose. If observed average solar diameter is nominally ~0.5 degrees, when viewed from sea level, then I think most could live with one decimal place of precision. :)

i.e. thus whether you're zoomed-in, or zoomed-out, the sun will remain the approximately correct size for that level of zoom, etc.

It seems to be that the brightness through the atmosphere (transmitted brightness varies as the angle to the horizon varies) which drives the degree of radiant flaring seen. So the radiant spikes appear more intense at noon, but weaker at sundown, simply because the apparent luminosity is much lower.

And the more intense the flaring, the larger the sun appears to become. So this flare effect needs a bit of winding back so that it is not bloating-out the apparent size.

Maybe diveplane or someone else can find an agreeable compromise so that the disk limb is seen fairly easily and crisply through the ambient radiance at sundown, as per reality most days, but is hidden by the surrounding brightness at noon.

2c

I'm not an expert regarding such things but I think calculating the size of the sun's disk is way more complicated. Especially if the sun is low, refraction and reflection in the atmosphere will make it look bigger than it actually is.

Maybe I will take a look at the sun with solar eclipse goggles this evening:smartass:

You said it yourself: you're not an expert. On the other hand, my hobby is amateur astronomy, and I've been doing it for most of my life (since I was 9 years old, in fact).

Calculating the size of the solar disk is pretty easy. It's 0.5 degrees across, in all cases except very, very close to the horizon, where the sun is actually shrunk vertically by atmospheric refraction by maybe 10% or so. So it's actually smaller near the horizon.

The idea that objects get bigger nearer the horizon is just wrong. However, it is a very real illusion that many people experience (I remember noticing it when I was a little kid, but after I started observing, I never really noticed it again), and it's caused by simply having something to compare the object to. Far above the horizon, the sun and moon just get dwarfed by the vastness of the sky.

So getting the sun accurate is very simple: just make it 0.5 degrees across. End of story. The vertical shrinking very near the horizon is just too minor of an effect to model.

Edit: but really, you don't have to take my word for it:

http://en.wikipedia.org/wiki/Moon_illusion

http://curious.astro.cornell.edu/question.php?number=230

http://wiki.answers.com/Q/Why_does_the_sun_look_larger_at_sunset

http://answers.yahoo.com/question/index?qid=20080723224517AAgx6ia

http://blogs.discovermagazine.com/badastronomy/2010/05/13/why-does-the-moon-look-so-huge-on-the-horizon/

:smartass:

I would say the problem ist not the size of the sun but finding the right size of the rays. The disk is almost imposible to spot, even at sunset.

I think this picture shows what I mean

Can you tell how big the disk is?

But I agree that the sun is way to big at the moment.

^^^

good point, what's not right in DCS is the rays... there is hardly any distinct rays to be seen, it's more of a glow around the sun that visible.

The image you've used simply isn't near enough to the horizon with enough of the sunlight passing through the thickest parts of the atmosphere, thus the light is not being attenuated enough:

Notice how in the second example the limb of the sun is crisp, and much sharper at the bottom where it is dimest, than at the top, where it is brighter.

This is what I'm referring to, and I can see how big the disk is when it gets like this. I've seen the disk of the sun clearly many times right on actual sunset. You can't look at it directly at any other time. On very clear days you still can't look at it, but on an average day you can.

If a mod created something like that limb clarity, right on sunset, then the radiance should be about right around noon as well.

As for 'rays' where are they? The flare diveplane is using is akin to a subtle camera lens 'flare' effect, plus 'rays' - which looks pretty good in his images, the only problem with it is that it's in the same location in each image.

Sunset1.bmp

Sunset2.bmp

Is there any way you could shrink it even more? A little over a year ago, I measured the sun in DCS to be 3 degrees across, six times larger than it is in real life, but maybe they've changed it since then.

If the sun were that big IRL, Earth's surface would be a sea of lava :)

LMAO :D

Another thought, the ED people who made the existing ray effect did it for a reason, to create an effect. And I don't dislike it. It looks quite nice.

They modelled the eye's response to light also, so, is this what the person who made it imagined a person might see, if squinting past a very bright sun, whilst maneuvering? Seems a reasonable thing to have done, in that respect.

So, back it off a bit, but I wouldn't want it gone. What a starring camera lens can show, and what a squinting human sees, are always different.

You guys are all wrong.....you have to divide the size by 14.5% because we can't actually see the real size. <---unless you have specialized lenses aka welders helmet. Also the sizes are different during different phases (where it's at in the sky). The rays and glow around the sun is misleading.

I have no idea what I'm talking about :D

I have no idea what I'm talking about :D

It went pretty well though. :D