suggestion - Sunlight independent control

[JimB]

Just a suggestion that would make tweaking and control over the final look a lot easier.

In the same way the GI can have different strengths on Atmospheres and Surfaces, it would help a lot to have a similar level of separated control for the Sunlight.

Cheers,
Jim.

[Njen]

Aye. though I do remember Oshyan saying that light inclusion and exclusions are something that is on the todo list for TG2. I would imagine down the track you would create 2 suns (light sources) in the same position, and have one affect the atmosphere with it's various settings, and the other affect the terrain with other settings.

[JimB]

I imagine that would double, or greatly increase, the render time? If the atmosphere sun is excluding the surfaces then I also imagine there would be no shadows cast on the ground, and vice versa.

Perhaps an easy way to independently control the exposure of the two parts is a solution?

[Njen]

No, this does not increase the rendertime. In other 3D programs it is possible, for example, you can have the ground recieve the illumination from one light, and the shadows from another. Or you can have the atmosphere only affected by one light, and pass the generated shadows through to other lights.

That being said, I am not sure how TG2 is going to handle it.

But what you are assuming is that people want to change the light in only 2 parts. What if they want the light to change for 4 different objects? Then a light inclusion/exclusion system is necessary.

[JimB]

I'm fully aware of other 3D apps and how they have exclusive and inclusive lighting, but twice the lights, if raytraced, is twice the raytracing. Even if it uses non-raytraced methods, the render time increases.

I fully agree that inclusive and exclusive lights are a must, but I don't think that has anything to do with a simple solution for those times when the clouds are too bright but the terrain is perfect, and then you have to potentially spend ages fiddling with the different colour values in the clouds. At the same time, there would be absolutely no hit on the render times in any way whatsoever.

[Njen]

It's only twice the render time of both lights are casting all their shadows on the same objects. But If one light is doing the casting, and the other light is receiving that shadow data from the first and is just purely illuminating, the second light does not need to recompute the shadows. Hence the addition of a second light in this case in relation to render time is trivial.

If you want a simple solution to darken your clouds, just adjust the Fake Dark Power. Is that what you were after?

[Njen]

Upon further inspection of how Terragen 2 works, I think it's safer to get your sky looking good, then if your terrain is too bright, then simply go to the Environment light and adjust the Strength on surfaces and Colour on surfaces values.

The reason is that, from what I see, the light in the atmosphere affects the terrain, but the light on the taerrain does not affect the atmosphere. So adjusting your atmosphere first is probably is a good work flow, now that I think about it. Then you just adjust the Environment light on the surfaces, or go to the shaders themselves and turn down the Apply Colour value to reduce the amount of diffuse light the surface receives.

[JimB]

Fake Darkness might do it, but then you also have to take into account the Sharpness. So, it just got more complicated than necessary.

But If one light is doing the casting, and the other light is receiving that shadow data from the first and is just purely illuminating, the second light does not need to recompute the shadows.

That just seems more complicated, as that would need to be a more complex setup, when all that is needed is couple of sliders as in the Enviro Light tabs, where you can fine tune the effect of a single light separately on Atmosphere and Surfaces. It also needs to be written in the app that one light lins to another. The fact is that the GI calculates and has controls for them separately already, so why can't a Sunlight have it?

I really believe it would be easier to just have the option in a Sunlight. What you suggest is interesting, but I always prefer a simpler solution.

[Njen]

Fake Darkness might do it, but then you also have to take into account the Sharpness. So, it just got more complicated than necessary.

It's really not complicated, just turn up Fake Dark Power, and if you want it even darker, adjust the sharpness, simple. Look I even provided a webpage that shows what it does visually:
http://www.motionmagnetic.com/terragen2/

That just seems more complicated, as that would need to be a more complex setup

Not as complicated as learning an entirely new node system in TG2, quite a bit simpler in fact.

The fact is that the GI calculates and has controls for them separately already, so why can't a Sunlight have it?

I am not sure if you understand the concept of Global Illumination properly. Global Illumination is the process in where surfaces receive light based on the colour and intensity of the environment (and atmosphere). By it's very nature, GI is the interaction of the atmosphere onto the surface. So like I mentioned before, if you increase or decrease the amount of light in the atmosphere, that affects the amount of GI the surface receives. So best get your atmosphere looking right, then you can choose how much affect the light from the atmosphere and the sun has on the surfaces. Simple.

JimB: I have the perfect, simple solution for you. Take what you have right now, Adjust the sky colour and intensity to something that looks good, then simply turn down the Strength on Surface setting in the Environment light and the Apply Colour in your shader to match what you had before.

[JimB]

I am not sure if you understand the concept of Global Illumination properly...

I also work in film VFX and been using Mental Ray since before it had GI. I'm sure I understand how it works. 

Adjust the sky colour and intensity to something that looks good, then simply turn down the Strength on Surface setting in the Environment light and the Apply Colour in your shader to match what you had before.

Instead of just a separate slider to adjust the surface brightness accordingly, or the sky's brightness, I have to modify two separate, unconnected values that can lead me to tweaking hell.

It would benefit from something that makes independent colour grade adjustment of the atmosphere and surfaces a breeze, after the GI is calculated. How, I don't know.

The reason is that, from what I see, the light in the atmosphere affects the terrain, but the light on the terrain does not affect the atmosphere.

I'm afraid it does. Change the surface and the GI will slightly change the cloud grade, most noticeably in the distance. There are *some* VFX Supers out there who would be very unhappy about the sky they loved so much changing at all.

Anyway, it was only a suggestion. I don't want to get into a ding-dong.

This is so people can see the effects of Fake Dark Power for future reference.

[rcallicotte]

Thanks for the comparisons.  This is helpful.

[Sarge-David]

something i been wondering about with the sun and such...how can you set up a moonlite scene?
im guessing something like placing the sun infront of another planet, lower its brightness and change the color to a white-blue
or have another light sorce infront of the moon to make it look like the sun reflected off of it....sounded like this is the best place to put it

[Njen]

I quickly whipped up something if you want it. I just turned down the strength for the sun to 0.04. Then I messed with the atmosphere a little.

I found a moon image on the net and Photoshopped it in.

[Dark Fire]

Wow! Very nice night scene there...

[Sarge-David]

the only problem with that is i don't have or use photoshop
its alittle like cheating lol

show me how to do that only in terragen