Making clouds with motion blur in LightWave

This is an alternative way to make clouds other than Hypervoxels. While I originally came up with it back when I used LightWave 5.6, it works with all subsequent versions including LightWave 9.6. The technique is based on motion blur. When you are finished, you should get something that looks like this (the final result will be animated):

Cloud Test Render

Modeling and Scene Setup

  • In Modeler, create a plane. Make it about 2 m x 2 m.
  • Assign a surface to it, such as “Clouds” and save the object as “clouds.lwo”.
  • Bring this object into Layout and move it down by 4m.
  • Scale the plane up approximately to 10000 along X and Z but leave Y at 1. This makes it look like an infinite plane.
  • Move your camera to X = 0, Y = 1.5 m, Z = 4.8 m. This is just so it's a bit higher than the clouds. Make sure the camera faces the positive Z axis.
  • Select the default light, and rotate it so it points toward the negative Z axis and down by 45 degrees. This simulates the sun being in front of the camera but high above in the sky.

Surfacing

Transparency Texture

It's time to surface the object. First, we'll create a fractal transparency texture that moves over time to create a cloud movement effect. It'll have a velocity on the Z axis and the Y axis. The Z movement makes the clouds fly toward camera, the Y movement generates a sort of reshaping cloud effect.

  • In the Surface dialog, select Clouds. Set the transparency to 100%
  • Add a fractal noise texture (Procedural Texture) for transparency, make the texture value 0%.
  • Set the frequency at 16, contrast at 1.8, small power at 0.6.
  • Enable World Coordinates
  • Use the following values for the scale and position of the texture:
PropertyXYZ
Scale5.5 m18 m16 m
Position000
  • For the texture position, keyframe the Y channel so over the course of your animation, it moves at 15 cm per frame upwards (this makes it look like the clouds are changing shape over time). Keyframe the Z channel so it moves at -85 cm per frame (moves towards the negative Z-axis to look like the clouds are flying towards you).

Color Texture

  • Set the base color to white.
  • Add a fractal noise texture for color, make the texture color RGB to be (164, 164, 164).
  • Set the frequency at 16, contrast at 2.0, small power at 0.7.
  • Use the following values for the scale and position of the texture (note that the texture center is offset by a bit from the previous texture so we can sort of simulate a shadow from the direction of the light):
PropertyXYZ
Scale4 m18 m16 m
Position-1 m0-2 m
  • Keyframe the position's Y and Z channels with exactly the same velocity as before, just offset by the starting position. Over the course of your animation, the Y channel moves up at 15 cm per frame while the Z channel moves toward the camera at -85 cm per frame.
  • Enable World Coordinates
  • I set the texture opacity to 45% because it looked better to me.
  • Copy the texture layer.

Diffuse Texture

  • Set diffue to 100%
  • Click the T and in the texture editor, paste the color texture layer (replace all layers).
  • Set the contrast to 1.8.
  • Set the texture value to 70%.
  • Leave all the rest of the settings

Luminosity

  • I set the Luminosity to 6% to brighten the clouds a bit.

Adding volume with motion blur

  • If you rendered a test frame, you'd get an idea of what the clouds looked like. They're a bit flat because it's a plane. What we need to do is to simulate some thickness to them.
  • Create a keyframe at frame 1 for the clouds.lwo object. Move the plane up to Y = 0 m.
  • Click Graph Editor and set the before and after Ending behaviour to “Repeat”.
  • In the Camera settings, choose the Classic camera. Turn on anti-aliasing (Classic Enhanced Medium) and activate Classic motion blur with 50% blur length. If you use higher AA settings, you get smoother clouds.
  • Don't forget to set up a sky coloured backdrop before rendering.
  • Save the scene, and save all objects so you don't lose any surface settings.

You can render from 1 to 60 and get a 2 second clip of clouds in flight.

What you've done is used Motion Blur to simulate depth in the clouds. By having it move up 4 m continuously every frame, you get a 2 meter thick cloud layer (since motion blur is set to 50%).

Discussion

Jon, 2011/04/30 09:33
I was unable to give the coulds depth in lightwave 9.6. They still appear to be flat.
Jon, 2011/04/30 10:25
It appears I had not select the classic camera, the coulds now have volume. Thanks
Peter Yu, 2011/04/30 10:50
Yes, the motion blur calculations for the other camera types is different so you need to use the classic camera to get this effect.
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About Peter Yu I am a research and development professional with expertise in the areas of image processing, remote sensing and computer vision. I received BASc and MASc degrees in Systems Design Engineering at the University of Waterloo. My working experience covers industries ranging from district energy to medical imaging to cinematic visual effects. I like to dabble in 3D artwork, I enjoy cycling recreationally and I am interested in sustainable technology. More about me...

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