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Moving cloudy sky

Alright, here's a fairly simple tutorial showing you how to create a sky backdrop with some cloudy motion, making it somewhat more interesting. It's all done through moving, procedural textures and the techniques can of course be applied to tons of other things. To be fair, most of this deals with fundamental Blender know-how, so this can be seen as a shortcut to a suitable cloudy texture created through some trial and error on my part, the goal being a swiftly moving sky backdrop without "resorting to" adding a photo of an actual sky - which would be hard to animate.

Mpeg 4 animation and Blender file can be found at the foot of the page.

To follow the tips, you need to be able to find your way around the Blender interface, adding objects and so on.

Things we'll be looking into:
Procedural textures (no imported bitmaps needed)
Applying textures and color to "the world"
Adding animation to textures with the IPO editor.

Setting the scene

For a foreground, I just added some colored cubes. Feel free to model a futuristic city or add a monkey instead.

Setting the angle

Place the camera fairly close the ground, looking up at the sky and the foreground objects. This makes them appear mighty, skyscraperlike almost.

The World settings

Now, we'll give the world a texture. Get thee to the World buttons (F5 for shading and click the button with the earth on it).

Adding a world

Click on the little dropdown arrow under "World" and add a new world (and feel free to marvel at the the powers bestowed upon you). A World block can contain lots of information about our surroundings, but here we're mainly interested in the sky color. This can be affected by both basic color and a texture.

The default settings for this brave little new world may vary depending on your blender settings and version, but let's start out by making the sky a nice gradient going from blue to white by changing the colors for the horizon and zenith and setting the background setting to Blend. See pic.

Adding a world texture

If you were to render the picture now, you would see a dull sky merely getting paler the higher up you look. Not so much fun.

Add a new texture to the world.

A cloudy texture

Get to the Texture buttons (F6).

Strangely, I don't use the Cloud texture option for the cloudy sky but a Marble texture, which gives a neater effect in this case.

Marbly cloudy settings

The settings shown in the pic can be a start. At this point, you can make some test renders to check out the result. You should get the general idea.

Mapping settings

If you get back to the world buttons and check out the settings under "Map to", there are a couple of things to take note of.

Even though the texture is by default a loud pink color, you (thankfully) see no trace of pink in the sky. If you were to activate the buttons beside "blend" (Hori, Zenup and Zendo) it would be a different story (and you might want to change the color from pink to... anything else). Also, the option "Mix" in the dropdown is highly... optional. By choosing "Multiply" you might for example get a result you like much better. Playing around with these settings is recommended and also fun.

Animating the sky

If you were to render an animation of the scene now, the sky would be cloudy but entirely static. The final touch is to add some animation, making sure the clouds are always moving restlessly.

Open up an IPO window and select World in the dropdown. Normally, you might add keyframes by moving an object and hitting the I key, but in this case this method is more convient.

To the right, you see the channels that you can animate. If you click on a channel, like "OfsX", it's activated, and you can add animation curve segments with CTRL+ left click (just like when you're editing a bezier curve object). The name of the channels with animation will be highlighted, so you see which ones are in use.

For a moving blanket of clouds, you might want to add some animation to the "OfsX" (meaning Offset along the X axis). This is slightly dull, however, so let's add one more channel.

In this example, I added some animation to the Z size channel. This will change the shape of the texture, which along with the X-ward motion will create enough turbulence for my purpose.

Perpetual motion
To make the motion perpetual, you can select an animation curve with at least two points and then go to the Curve dropdown. Choose Extend mode / Extrapolation. This will extend the motion infinitely.

The options Cyclic and Cyclic Extrapolation are very handy for looping motions, try them out and you will see how the curve is affected. Now you can change a single handle to have this looping motion repeated ad infinitum. This, by the way, is the easiest way to make a constantly spinning object, e.g. a globe.

Example files
Below, you'll find the animation and the .blend file.

 Media files
Cloudy sky .blend file

An example file with the cloudy sky Blender project to be used when all else fails.

File format: Misc
Cloudy Sky animation

An mpeg 4 animation showing the results of the cloudy sky tutorial.

File format: Video


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