CLOUD TUTORIAL [ AFTERBURN ] [ 10/11/02] by Daniel P.Ferreira>>

Hi! I will explain how I made the cloud scene. If you follow this steps you will be able to reproduce the scene.

First of all, you must know how the clouds are created. The clouds are rendered with Afterburn, a plugin for 3DStudio. If you don't own Afterburn and 3DStudio MAX, you won't be able to reproduce it. So come on and go to buy them :)
[ you can also download the afterburn demo, of course :) - http://www.afterworks.com/ScatterVL.htm ]
The clouds are made of particles. Each particle creates a single "smoke blob". When a lot of them are near, can look like shapes when rendered.
Here is the render of a single particle:



To create the "cloud fields" I placed a lot of "pcloud" objects [ pcloud is in the particle system menu ] with box and sphere shapes with enough particles inside to achieve a uniform cloud.

This is a box-shaped pcloud with 57 particles inside. Look at the result achieved.
In the pcloud object dialog, you can specify the dimensions, the shape and the number of particles over other parameters. To create clouds, you don't need to modify the motion or collision parameters. The particles will appear static. But you can always create a wind object and link it with

Of course, you need to set up the parameters in afterburn and the lights correctly. I will cover that now.



These are the parameters of my clouds.

The shape of the cloud is achived using different kind of fractal algorithms. [ Noise sharp parameters , in the afterburn dialog ] For these, I used fire wall turbulence without density falloff by radius. You can also achive more dense clouds or fragmented changing the [ gain ] and [ bias ]. I used the default values this time.

You should note that some parameters are animated through the life of the particle, the most impostant is phase. That is the fractal seed of the volumetric smoke. When incrementing the value through time, the noise of the particle changes too. That makes the clouds to be "alive". The important thing with phase is that should not be noticed. If you check the animation and you focus in a distant part of the cloud, you will notice it's changing shape with time but very slightly. That's the phase. The particles are static themselves.



It's very important to experiment different values and do a lot of test to discover how does every parameter works.



This is a snapshot of the project.

I placed the pcloud objects from the camera in a triangular distribution because the afterburn renderer is very processor intensive and I wanted to place only the minimum possible particles in the scene. So, I placed them in the range of the camera.

The camera is moving forward, so I also had to put a lot of pcloud objects along the camera path and beyond. (see image).




Here you can see the size of the particles in the viewport.

It's important to create more pclouds below the main ones, made them thick, and generate enough particles inside them, because to achieve a continous cloud, there should be no gaps.
In the scene, I placed 36 pcloud objects with 20 to 400 particles inside each one. This can be a little tedious, so activating the afterburn "show in viewport" icon can be very useful.

The average size of the pcloud object was 800x250x25.




Here is the rendered image.

I have only one direct light from the left.
Is a white light with multiplier 1.0 and very broad beam, so it can cover the whole scene.
It's important to set the shadow type to afterburn raytraced to get accurate shadows.
Also, the scene have some afterburn volume fog [ also in the environment dialog ] to achive some "depth".




Here is the post processed image.

I tweaked the colors, softened the shadows, etc.



I hope this tutorial was useful. I focused on showing the techniques. I din't want to show how to copy the scene, but how you can make similar ones.

     dpf@wonderslime.com