Chapter 7. Haunted House – Adding Materials and Lights in Cycles

This chapter will be devoted to the Cycles render engine. You will learn how to achieve a convincing render of the haunted house by understanding the different types of light work and by creating complex materials using the previously made textures. You will learn some nice tricks such as how to produce normal maps of our hand-painted textures without leaving Blender or how to create realistic-looking grass. You will also discover how to use the Cycles baking tool. In order to conclude our project, we will show you how to integrate a mist effect in the final composition.

In this chapter, we will cover the following topics:

• Understanding the essential settings of Cycles
• Using lights
• Painting and using an Image Base Lighting
• Creating basic materials with nodes
• Using procedural textures
• Baking textures in Cycles for real-time rendering

Understanding the basic settings of Cycles

To switch to the Cycles render engine, you must select it in the list of proposed engines that Blender offers in the menu bar. We will see in the first part of this chapter some of the very useful settings that should be known while using Cycles.

The sampling

If you directly try to make a render with Cycles without changing the parameters of Blender, you will certainly see some noise in the image. To make this less visible, one of the first things to do is change the sampling settings. Unlike Blender Internal, Cycles is a Raytracer Engine. While rendering, Cycles will send rays from the camera in order to generate pixels. The noise is due to a small amount of the samples. Cycles, therefore, needs more samples; the more sampling, the more accurate the final render.

The following sampling settings are in Properties editor. Just select Render | Sampling:

• Render samples: This is the number of samples for your renders. The more samples you add, the longer the rendering time will be.
• Preview samples: This is the number of samples Blender will calculate to preview your scene in the 3D viewport in Rendered Viewport Shading. A value between 20 and 50 samples is correct. This value depends on the performance of your computer.

The Render sample must be higher than the Preview sample.

Note

The GPU device

If you have a fairly recent CUDA®-compatible graphic card, you can opt for GPU rendering. This allows you to make renders very quickly and visualize your scene in the 3D viewport nearly in real time.

For this, go to User Preferences | System | Computer Device and select CUDA. Then, in Properties, go to Render | Device and select GPU.

Note that the most recent AMD GPU has been supported since Blender 2.75.

Clamp direct and indirect

This allows us to clamp the intensity of the rays of light launched from the camera. This can also help to reduce the noise effect, but it blurs the pixels together.

Light path settings

You will find the following light path settings in the menu:

• Max and Min Bounces: This is the number of minimum and maximum bounces a ray of light can do in the scene to render a pixel. This mimics the way photons bounce from objects in real life. The higher the value of the maximum bounce, the greater the precision will be, and the quality of the rendering will increase. A high value of minimum bounce will also improve the quality but may considerably increase the rendering time. It is advisable to set the same minimum and maximum value.
• Filter Glossy: This will blur glossy reflections and reduce the noise effect. You can put a 1.0 value.
• Reflective and refractive caustics: Caustics are light effects related to transparent and reflexive materials. We can observe this light effect with diamonds, for instance. This uses a lot of resources and generates some noise. By unchecking these two options, you can completely turn off these effects during rendering. In the case of our haunted house scene, we are going to disable them.

Performances

You will find the following performance settings in the menu:

• Viewport BVH Type: There are two types of this: Dynamic and Static. This is a way to let Cycles remember some of its rendering calculations for the next render. The Static option is highly recommended to optimize the rendering time, if you have no more polygonal modifications in your scene. Otherwise, you can use the Dynamic mode.
• The Tiles: This helps to manage the pixel groups that are to be rendered. So you can control their size along the x and y axes and also control the method to render the image (if you prefer to start rendering through the center of the image, or from left to right, and so on). The size of the pixel group to be rendered should be chosen according to your machine settings. If you are rendering with your CPU, you can choose a smaller tile size than if you were rendering with your GPU.

Note

For more information, you can have a look at the official Blender manual at these addresses:

http://www.blender.org/manual/render/cycles/settings/integrator.html

http://wiki.blender.org/index.php/Dev:2.6/Source/Render