Render Settings (Basic)

TRACING DEPTH

Tracing depth is an important parameter for progressive engines. Increasing this parameter may be necessary for certain cases where there are a log of mirrors or dielectrics in the scene, but it has a direct impact on render times. Ranges from 1 to infinite.

Here are a few examples of how tracing depth affects a scene.

Example 01: In this first example, notice how the light starts bouncing around the scene and increasing the overall brightness when we increase from 1 to 5. Notice how there is no light bouncing around the scene when tracing depth is set to 1. This means that the scene is being lit only by direct light.

Tracing Depth: 1 Tracing Depth: 2 Tracing Depth: 3 Tracing Depth: 4 Tracing Depth: 5

Example 02: In this second example, we added two glass spheres to see how does tracing depth affects the reflections and refraction too. Low tracing depth values result in darker transparent and reflective materials. Notice how the glass starts to have more reflections as we go from 1 to 10.

Dielectrics: Tracing Depth Set to 1 Dielectrics: Tracing Depth Set to 2 Dielectrics: Tracing Depth Set to 3 Dielectrics: Tracing Depth Set to 4 Dielectrics: Tracing Depth Set to 5 Dielectrics: Tracing Depth Set to 10

High tracing depth values have an impact on render time. Instead of increasing tracing depth to get the reflection / refraction right, you may use the Extended Tracing option while keeping tracing depth to its default value (5).

DIFFUSE DEPTH

Diffuse depth is a separate value that controls tracing depth for diffuse surfaces. Setting diffuse depth to 0 removes all light bounces from the scene, leaving only the direct light. This option can come in handy when combined with Ambient Occlussion to mimic a part of the global illumination and compensate for the missing light bounces.

In the following example, we will be using the following settings:

  • Tracing depth: 5
  • Diffuse depth: 0 to 5
  • Extended tracing: Enabled

As you might notice, the transparent surfaces are using the tracing depth values to handle the reflections while the light bounces are now controlled only by the diffuse depth parameter.

Diffuse depth set to 0 Diffuse depth set to 1 Diffuse depth set to 2 Diffuse depth set to 3 Diffuse depth set to 4 Diffuse depth set to 5

POINT LIGHT INTERSECTIONS

Point light intersections makes point lights visible when the soft shadows option is enabled. This option also speeds up rendering caustics coming from highly reflective materials.

Example: This scene has one point light with soft shadows enabled and set to 0.01m. There are two things that we can see in the second image where the point light intersections option is enabled.

  • The first one is that the point light is visible and has the size that we set in the light settings (1cm)
  • The second one is that the reflective and refractive caustics are sharper and more intense

Point light intersection: Disabled Point light intersection: Enabled

EXTENDED TRACING

Extended tracing can efficiently render scenes with transparent objects or materials with subsurface scattering while using a lower tracing depth. Take advantage of extended tracing and lower render times significantly.

Example: In the following scene, we have placed 7 surfaces, one after the other.

  • Image 1: Tracing depth is set to 5 which is not enough to deal with the transparency and this is why we get black in the refraction
    Render time: 4m 38s
  • Image 2: To get rid of this we actually need to increase tracing depth from 5 to 30 but this also has an impact on render times
    Render time: 6m 52s
  • Image 3: Instead of increasing tracing depth, we used the default value (5) and enabled extended tracing with a value of 25.
    Render time: 5m 54s

Image 1: 4m 38s Image 2: 6m 52s Image 3: 5m 54s

CLAMP LEVEL

Clamps the evaluation of a pixel, improving antialiasing. Lower values, clamp very bright paths that might lead to excessive noise.

Example: In the following scene, a point light is illuminating the scene. The whole scene has noise that is generated by the light bouncing on the walls. Notice how much cleaner the second image is when we lower the clamp level from 1.0 to 0.2 and then 0.1.

Clamp level set to 1.00 Clamp level set to 0.20 Clamp level set to 0.10

Be aware that if you use very low values for the clamp level parameter, this may result in a very low dynamic image.

RANDOM GLINTS

Random glints is used to create glittery surfaces containing small mirror-like flakes that react to light. Enabling this option will turn on the feature globally. Random glints can be then added on a material level.

AMBIENT OCCLUSION

Ambient occlusion is a technique that can be used to mimic a part of global illumination and decrease render times. Extreme ambient occlusion intensity values may lead to a washed out and flat image.

Example: In this example, we compare two different setups. The first image was created with the default settings having tracing depth set to 5. In the second image we enabled diffuse depth and set it to a value of 1. We also enabled ambient occlusion (distance: 5, intensity: 2). In this way, we limited the light bounces from 5 to 2 and used ambient occlusion to compensate for the missing bounces. As expected, there are some differences in the overall lighting of the scene but we managed to decrease the render time from 180 to 72 seconds (~ 2.5x faster).

Image 1: Default Settings - Ambient Oclussion: Disabled Image 2: Ambient Oclission: Enabled - Diffuse Depth: 1