Houston, We Have Sunbeams!

You may have noticed that the images at the beginning of each of these sections shows the Sunbeam effect of the Sky plugin. They were all done by the Master of the Killer Sky in Bryce, ZBrush and, now, Cinema4D, Paul. While we can't promise the same results for you, we will show you that Sunbeams can be easily achieved, if you understand a few settings and how they work. Be forewarned that the final results require a heavy amount of tweaking at the very end, but the impact is well-worth the time.

Because Sunbeams are heavily dependent on the Sun's position in relation to Clouds, and the Cloud settings have a direct impact on the appearance of Sunbeams, we're going to look at what's going on with Cloud layers, and how to change some settings to improve the final image.

Open up the Default Sky Object, or the custom sky scene you downloaded, and then to Plugins/Sky/Sky Manager, then to the Cloud tab.

You'll notice that all cloud layers are active, except Layer 6. First thing, uncheck all Layers by clicking on the eye icon. You should now have a clear sky. On the Rolloff gradient, change the second Knot to about 1/4 inch to the left, which will give more definition to the haze along the horizon. Now reactivate Layer 2.

Layer 2 and Layer 3 work together, Layer 2 being the white part of the Cloud formation, and Layer 3 adding darkness and density.

These Clouds are a bit small to work with, because what we want to do is block most of the Sun, so it just peeks out at one or two edges. They are also a bit low, so in the Height box, put a "1" in front of the "770" (1770). At the bottom, in the Scale W-E box, raise the percentage to 200%.

By changing just the Height and Scale settings...

...you should now be seeing something like this.

Activate Cloud Layer 3, and change the height and scale in the same way: add a "1" in front of the Height, making it 1732, and change the W-E Scale to 200%. This will insure it moves in the same relation to Layer 2 as it had before. You can begin to see that the Sun is already positioned fairly well behind the clouds. If your Sun is not as shown, go to the Astro tab, select Sun from the drop-down list, uncheck Auto, and change the Azimuth to 132 and the Altitude to 33.

Activate Cloud Layer 6. You'll notice this is a very high Cloud layer already, so we won't change the height here. Down at the bottom, change the Scale N-S to 400%, and the W-E to 200%. This will really beef up those clouds and give us more to work with when creating the Sunbeams.

These are just the parameters we need for our Sunbeams, and there are many more to experiment with. You might like to change the Noise used, the Coverage, or Density. All can have a dramatic impact on the final image. By changing the Color to a peach or gold, and increasing the Transparency, especially in Layer 2, you can increase the impact of your image tremendously.

On to the General tab!

We'll only change a few settings here, but they're important. First of all, reduce the Turbidity to 20%. Without Turbidity, you won't have Sunbeams, but with too much, your scene will look like a hazy day, and we want a clear day. Change the GI Mix to 100%, and reduce both Lens Flare settings to 0%, so they don't interfere with the Sunbeams. Take the Horizon Start down to minus 10 to increase the space we have to work with along the Horizon, and make sure that Atmosphere Strength is at 100%. We're all set!

If you Sunbeams box on the right isn't already checked, do so now. This will add a Sunbeams tab to your Sky Manager, to which we'll now go... finally!

The first thing you probably noticed, is that there are very few settings in the Sunbeams tab, but the ones that are here control the amount, strength and definition of the Sunbeams.

Most importantly, uncheck the Turbidity Dependent box. If you leave this checked, you'll increase the amount of work to the point of distraction! Change the Intensity and Min Brightness to 70%. This is just a starting point. What 70% should do is "blow out" your Sunbeams, so that all you see when rendering is a white glare. For now, leave the Sampling Distance at 500.

A word about the settings, so you know what we're doing.

The Intensity controls the size and strength of the Sunbeams. Too much, and all you'll see is a solid white halo around your Sun, too little, and you will have Sunbeams too faint to be seen.

The Min Brightness tells Cinema how much of the Sunbeams to render. If this is set at 100%, you will have basically no Sunbeams and too much contrast, because only the rays that are 100% strength will render. If Min Brightness is too low, it will render all of the rays, and you'll be back to a solid white halo around the Sun.

Balancing those two settings is where all the tweaking comes in. You really do have to a) move in very small increments (2-5%), and render a lot to see the results. No two scenes will take the same settings here, because it is so dependent on the position of the Sun behind the Clouds, your Atmosphere and the camera angle.

The last setting, the Sample Distance controls the quality and definition of your Sunbeams. We are leaving it at 500 for now, to speed up test renders. For your final render, you'll want to set this down to at least 200, 100 if your machine can handle it.

A test render now will show how the Sunbeams Intensity is too high: there is a solid white area below the Clouds that are the Sunbeams, but there are too many, so they blend into one big mass. We'll have to adjust the Intensity and Min Brightness so we can see if we need to move the Sun more behind the large cloud. Remember, we want the Sun to just be peeking out a little bit.

The Intensity was reduced by small increments, down to 60%, while increasing the Min Brightness up to 80%, resulting in the image below. At this point, the Sun seemed to low.

Under the Astro tab, the Sun's Altitude was raised to 26, putting it more behind the large Cloud. We can now see definite Sunbeams, and just a few more changes will give us a good result.

Changing the Sample Distance to 200, so we can see how much definition in the Sunbeams will have. This render will be substantially slower. Not great, so further tweaking of the Intensity, Min Brightness, and Rolloff (under the Cloud tab) is needed. At this point, please experiment with those settings, and the color of your Sun and Cloud layers!

For my final render, I changed the Color of the Sun (under the General tab) to a pale yellow, the color of Cloud Layer 2 (under the Cloud tab) to a pale peach, and increased the W-E scale of Cloud layer 6 to 300%. I also reduced the Sunbeam Intensity (under the Sunbeam tab) to 58% and increased the Min Brightness to 84%. I also move the second Knot in Rolloff (under the Cloud tab) a tiny bit to the left once again.

Next, I inserted a Scene Camera, so I could experiment with views without losing the original. To do this go to Objects/Scene/Camera, then in your View port go to Scene Camera/Camera. It will default to the current view, but, when selected in the Objects Manager, you can move it anywhere you like, giving you the option to look at the scene from any angle. I just moved it slightly to the left. Note: if you changed the Sample Distance back to 500 to save rendering time, don't forget to set it back down to 200.

While this image certainly isn't up to Paul's Killer Sky level, it should give you the basics for creating Sunbeams, and explain how some of the settings can affect the final result.



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