Big Sun

Started by RichTwo, October 10, 2019, 01:03:28 pm

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RichTwo

Back in the Terragen Classic days, it was fairly easy to create a scene featuring an oversized sun in the sky.  This took some thought, but it wasn't too difficult.  Even though for me thinking doesn't always come easy... ::) 

There are two sunlight sources here in the same location.  One is the default which is "inside" the large one that has been greatly reduced in strength, and none on surfaces.  I had to tweak haze settings and applied a global cloud layer to get the effect of the sun fading into the atmosphere near the horizon.
You don't need a weatherman to know which way the wind blows...

Matt

Hi Rich,

Is it more difficult to create a scene with an oversized sun in TG4 than in Classic? If so, what is more difficult about it? Did you need to use two suns to work around some problem with using just one sun?
Just because milk is white doesn't mean that clouds are made of milk.

RichTwo

Hey, Matt!

Yes, I tried as sunlight source alone and to achieve adequate lighting (usually the default 5 or more strength) but it always "bleached out" the disk and looked to me rather one dimensional.  With my setup you see a bright area in the center.  Maybe not realistic in every way to a natural view, but it gives a sense of a round sphere, or so I think.

If there is another way to get a good giant sun, I certainly am open to suggestions.
You don't need a weatherman to know which way the wind blows...

Matt

October 10, 2019, 05:18:08 pm #3 Last Edit: October 10, 2019, 05:22:58 pm by Matt
Ah I see. Classic also produces a flat disc, so I still wonder if there's something we could do differently to make it more like Classic (in a good way) since it seemed like that's what you wanted, but maybe I misunderstood?

Classic adds some softness to the edge, but you can do this in a more realistic way with TG4 by enabling bloom on the renderer's Filters tab.

I find that making the atmosphere much denser than the default can give you a nice gradient from top to bottom, and that helps avoid the flat look.
Just because milk is white doesn't mean that clouds are made of milk.

Oshyan

What exactly is the effect you are trying to create? It's not *just* a large sun, right? Because that's fairly easy in Terragen 4 as well.

Use "Visible Disc" in the Sunlight node settings and increase Angular Diameter until you get the size you want. If you are rendering with water/reflection, increase "Minimum highlight spread" until the reflection size of the sun matches the visible size in the sky. Files attached for example.

If that's not what you want, then some details/example would be helpful (it could be an image from TG Classic, for instance). 

If it is that you don't want the sun disc to be so sharp-edged, then admittedly that might be an issue. But this is generally how it is in real-life too. The sun is pretty uniform across its visible surface most of the time, at least to the naked eye (if you dare look that long :D). Sometimes it will have a gradient of color near sunset as it descends into haze and light gets scattered disproportionally at the top vs. bottom. But as far as I can think of it shouldn't be noticeably brighter in the center vs. edges. I've attached an image and TGD also demonstrating sunset across the visible disc (which is a cool effect).

Note that all of this is a faked, i.e. not realistic, approach. I know realism is not necessarily everyone's first priority. But if you want to replicate how photographers achieve the large sun look, you would keep Visible Disc the same size and instead zoom in with the camera, i.e. use a narrower FoV, a longer focal length.

- Oshyan

RichTwo

Using a single large sun with an atmosphere to soften is what I would do with Classic.  And because that produced less detailed and realistic reults, it could pass as a pretty cool effect.  (Hey Matt - how about being able to create sunspots on the disk... ;D ?)

Anyway - something like this but being the main light source?

Thanks so much for your interest, y'all!
You don't need a weatherman to know which way the wind blows...

Oshyan

The big sun setup I posted will do exactly that, as far as I can see from the example image. But the brightness of the disc is controlled by the strength of the sunlight and may be brighter than you want vs. the amount of light you want in the scene. i.e. you may want a not real-world amount of light for a given disc brightness. That's the kind of control that can be a bit harder to achieve given Terragen is largely oriented toward more easily achieving realistic results and thus tends to have real-world correspondence between effects like sunlight disc brightness and lighting of the environment. However if you increase Enviro Light Strength with a lower Sunlight level you may get something like the effect you want, based on the above file examples.

- Oshyan

Dune

Why don't you use a very illuminated planet with atmo as a sun? You can have your black spots (mask out luminosity), and use the atmo to get softness and solar flares.

DocCharly65

Nice project!

I think, Ulco's suggestion could work. I used a similar way some time ago successfully.