Creating Visual Effects Using Renderman

Visual effects using Renderman are normally used to make the end result of a scene more appealing and realistic. Using special-purpose shaders is very important when it comes to doing this. Effects such as volumetric lighting, layered texture and ray tracing can be done using special-purpose shaders. As their names suggest, they can be tailor made to fit your scene. In this article, you'll learn how to apply volumetric lighting to your animation and about the kinds of tools that need to be used.

Step 1: Shaders and Positioning

In this scenario, you have to select a good combination of shaders. For the purpose of this article, volumeSpot.slo and volumeFog.slo will be used. This combination is good for creating amazing imagery with effects of volumetric lighting, which normally takes some time to complete. The reason why it takes a lot of time is because of the shading calculations that need to be done. After you have selected the necessary tools, you will then need to create a spotlight in your scene. The next thing that you will need to do is set the position, the cone, the angle and the orient using the standard tools of transformation.

Step 2: In Slim

You now have your spotlight created and the positioning already done. The next thing that you will need to do is to import volumSpot.slo and attach it to the spotlight that you just created. After that, import volumeFog.slo and in the name field requirement, input the name “world”. This will bring out an effect that will make it the default atmosphere shader for your work.

Step 3: VolumeSpot Control

The next thing to do is to turn on the volume computation in volumeSpot. Once you have done this, select an option for the Sample Size requirement. This could have a really big effect on the time taken to render since it controls how much of your volume sample is needed. This is normally the distance in world units in the middle of the 2 volume samples. When starting, you might want to have large sampling numbers and as you move to the last images, you might want to select sampling numbers that are much smaller in order to have a better quality. This means that you will be able to reach the largest number, which will give you standard quality at rendering time.

Confirm on the other parameters the control motion, fog and shape. It is important to know that there is a procedural fog “gobo” that normally gives additional volumetric streaks without you having to enable the computations for shadow.

Step 4: Rendering

This will take some time, which will allow you to take a small break and refresh your mind and ideas. It is, however, important to note that the fog will appear in front of the surfaces that are rendered. To get the effect that you would like, you may need to put in or insert a floor or wall. This will bring better results.