Student: The parallel light problem

[bobbystahr]

Here is an example project. This has all sides illumination set to 0.2 except for the top face, which is at 1.

thanks 4 sharing man!

[noahding]

First of all, I'm really sorry that I forgot to translate.
Thank you very much for your answer
This is the VDB of the entire sky that I exported on Linux and then set up a parallel light rendering in C4D in 6 directions (X.-x Y. -y Z.-z).
But using sunlight in Terragen didn't get the desired effect. But sunlight is valid for a single object or a cloud.
It would save a lot of time if Terragen could directly produce the right light in all six directions of the sky
I have uploaded the Terragen file I used for testing

[noahding]

First of all, I'm really sorry that I forgot to translate.
Thank you very much for your answer
This is the VDB of the entire sky that I exported on Linux and then set up a parallel light rendering in C4D in 6 directions (X.-x Y. -y Z.-z).
But using sunlight in Terragen didn't get the desired effect.
It would save a lot of time if Terragen could directly produce the right light in all six directions of the sky
I have uploaded the Terragen file I used for testing

[noahding]

Terragen's Sunlight node emits light in parallel rays.

By changing the Sunlight node's Heading and Elevation settings you can change the direction of illumination.  In the first example image below, the Heading values of 0, 90, 180, or 270 degrees correspond to North, East, South and West illumination, and the Elevation values of +90 or -90 correspond to top and bottom lighting.

In the second example image, six Sunlight nodes are added to the project, each one corresponding to North, East, South, West, Top, and Bottom.  Each Strength setting = 1, and the Bottom Sunlight node's Cast Shadows option is off.

For more information on the Sunlight node, check out the Wiki documentation here: https://planetside.co.uk/wiki/index.php?title=Sunlight

First of all, I'm really sorry that I forgot to translate.
Thank you very much for your answer
This is the VDB of the entire sky that I exported on Linux and then set up a parallel light rendering in C4D in 6 directions (X.-x Y. -y Z.-z).
But using sunlight in Terragen didn't get the desired effect. But sunlight is valid for a single object or a cloud.
It would save a lot of time if Terragen could directly produce the right light in all six directions of the sky
I have uploaded the Terragen file I used for testing

[Hannes]

I haven't yet understood, what you want to achieve. Six parallel lights at once? What's the benefit?

[noahding]

In the test of the mobile terminal project, the correct light range of the sun shining on the cloud was simulated in UE with the light texture in 6 directions, so as to achieve the cloud effect with low performance consumption

I haven't yet understood, what you want to achieve. Six parallel lights at once? What's the benefit?

[Hannes]

Ah, I see. Thanks for the explanation.

[WAS]

I gave you a solution that provides the same sort of look. Which is actually the same method UE uses, box sky lights.

[Matt]

This is the VDB of the entire sky that I exported on Linux and then set up a parallel light rendering in C4D in 6 directions (X.-x Y. -y Z.-z).
But using sunlight in Terragen didn't get the desired effect. But sunlight is valid for a single object or a cloud.
It would save a lot of time if Terragen could directly produce the right light in all six directions of the sky
I have uploaded the Terragen file I used for testing

You could turn off "Render surface" in the Planet node. Apart from that, your TGD looks like it should work. What was wrong with the Terragen renders? Do you want more contrast in the shading? You might get more contrast if you increase the cloud density. "Millions of voxels" might need to be higher too, but I'm not sure in this particular case.

[noahding]

I gave you a solution that provides the same sort of look. Which is actually the same method UE uses, box sky lights.

You mean make a box and import Terragen to wrap the whole sky. The six sides of the box simulate 6 directions of light to bake 6 light textures?
I have tested terragen's surface light before, but the surface light is too soft. Can Terragen adjust the attenuation of surface light?
Thank you very much for your answer!

[WAS]

I know you can play with the lighting settings of the clouds, as well as the density settings. But yes, it is pretty soft/flat. It also is approximated, so probably not very accurate. I'm not sure if there is a way to add to that approximation's precision. @Kevin Kipper or @Matt would probably know for sure. I do feel this should work much better, like it does in Blender and other programs where an area light is parallel to the plane's surface. So if it's flat, you have an area of straight light rays from the surface.

[Matt]

I know you can play with the lighting settings of the clouds, as well as the density settings. But yes, it is pretty soft/flat. It also is approximated, so probably not very accurate. I'm not sure if there is a way to add to that approximation's precision. @Kevin Kipper or @Matt would probably know for sure. I do feel this should work much better, like it does in Blender and other programs where an area light is parallel to the plane's surface. So if it's flat, you have an area of straight light rays from the surface.

For parallel rays (a directional light source), the Sunlight node is the best choice. If the light direction needs to be softened, you can increase the soft shadow radius. The soft shadow radius causes it to be an area light as far as the clouds and atmosphere are concerned.

[WAS]

It would be nice to see improvements, as the sun technically is not a good choice at all, its a spot light essential, and is very noticeable as such when you use an object with its specular highlighting. This will even influence how the clouds receive direct light, especially with TGs issue with sun burning in clouds (creating giant hard glow circle that the first lighting setting can't spread out enough). Will soft shadows really somehow effect highlights?

To me it's very obviously like shining a flashlight with cascading rays. This will most certainly effect the Y+/Y- look like it does for any overcast scene looking at the sun area.

[Matt]

It would be nice to see improvements, as the sun technically is not a good choice at all, its a spot light essential, and is very noticeable as such when you use an object with its specular highlighting. This will even influence how the clouds receive direct light, especially with TGs issue with sun burning in clouds (creating giant hard glow circle that the first lighting setting can't spread out enough).

Noah's request was for parallel rays similar to those found in a parallel/infinite/distant light in other renderers. In Terragen the equivalent of this is the Sunlight node.

Yes, this produces a bright spot in the clouds in the direction the rays are coming from, but this can be turned off with "Glow in atmosphere and clouds" in the Sunlight parameters.

Will soft shadows really somehow effect highlights?

Yes, the soft shadow radius will widen and soften out the bright spot in the clouds. (On surfaces the specular highlight doesn't quite work this way at the moment, but luckily we're talking about clouds here.)

To me it's very obviously like shining a flashlight with cascading rays. This will most certainly effect the Y+/Y- look like it does for any overcast scene looking at the sun area.

The self-shadowing rays will be softened by increasing soft shadow radius, as it simulates an area light.

[WAS]

It would be nice to see improvements, as the sun technically is not a good choice at all, its a spot light essential, and is very noticeable as such when you use an object with its specular highlighting. This will even influence how the clouds receive direct light, especially with TGs issue with sun burning in clouds (creating giant hard glow circle that the first lighting setting can't spread out enough).

Noah's request was for parallel rays similar to those found in a parallel/infinite/distant light in other renderers. In Terragen the equivalent of this is the Sunlight node.

Yes, this produces a bright spot in the clouds in the direction the rays are coming from, but this can be turned off with "Glow in atmosphere and clouds" in the Sunlight parameters.

Will soft shadows really somehow effect highlights?

Yes, the soft shadow radius will widen and soften out the bright spot in the clouds. (On surfaces the specular highlight doesn't quite work this way at the moment, but luckily we're talking about clouds here.)

To me it's very obviously like shining a flashlight with cascading rays. This will most certainly effect the Y+/Y- look like it does for any overcast scene looking at the sun area.

The self-shadowing rays will be softened by increasing soft shadow radius, as it simulates an area light.

Thanks for the explanation, and suggestions there with glow, I always thought that turned off highlighting in general so never bothered with stuff like thick clouds. All this information is handy.