Render Quality is adjusted by moving the slider between the left end (lowest quality) to the right end (highest quality), or by entering a value in the input field:

Render quality settings

Selecting the Show settings checkbox gives you full access to detailed settings that all affect the render quality. The slider bar is linked to all settings, so as it is dragged, the quantities in the following properties are automatically adjusted.

General

Images produced in CET are usually rendered with a technique called Ray Tracing. Ray tracing involves firing and following rays that originate from the pixels in the view plane. The General section contains options for controlling how many times a ray may bounce/intersect an object’s surface before we stop following the ray.

Assume that your drawing contains a marble floor and a glass wall.

1. A ray is fired from a point in the view plane.
   Total bounces/intersections = 0
2. The ray bounces off the marble floor because the floor is reflective.
   Total bounces/intersections = 1
3. The reflected ray then hits the glass wall.
   Total bounces/intersections = 2
4. In order for the glass wall to be visible in the marble floor, Transparencies must be set to at least 2. If set to 0, transparent objects become completely invisible.

Transparencies

Increasing transparencies will allow a higher number of transparent surfaces to be seen through each other. Think of looking through a glass cup and being able to see through both sides. If set to 0, transparent objects become completely invisible.

Shadows

If set to 0, there are no shadows visible.

Reflections

If set to 0, there are no reflections visible; if set to 2, reflections are visible after two bounces and so on. Think of 2 mirrors facing; the higher the number of Reflections, the more times the scene is reflected back and forth through the reflective material.

Refractions

Refraction is how light is bent through a material. For example, when you look at a glass of water, light and objects appear distorted. 

Anti-alias

This is a technique that is used to make lines and edges look smooth and less jagged, which adds extra quality to your photos. Bear in mind, however, that the more anti-alias you use, the longer the rendering time. Although not consuming extra memory, a rendering with 3X anti-aliasing can in rare cases be up to 9 times (3*3) slower than a rendering completely without anti-alias.

Sampling

Increasing the number of samples generally produces an image with less noise i.e. random variation of brightness. Increasing the number of samples can be thought of as increasing the number of rays fired to produce the final image, as described in the General section above.

Area sampling

When turned on, lights will produce smoother shadows at the expense of longer render time. When turned off, the values for Light sampling, Adaptive threshold, and Adaptive sampling will be locked.

Light sampling

Amount of samples being taken for each pixel. Increasing this value will produce smoother light and shadows at the expense of longer render time.

Adaptive threshold

Adaptive sampling can be used to speed up the render time. Typical values for adaptive sampling threshold are in the 0.001 – 0.01 range; starting at 0.005 for the effect to be noticeable. Higher values allow more errors which in turn requires fewer samples; resulting in the image being rendered faster.

Adaptive sampling

Typically, this value should be set to 1 to enable faster rendering. If set to 0, the graphics engine uses an outdated sampling solution which will make rendering take longer. The zero option only remains for backward compatibility reasons.

Glossy effects

When turned on, reflections will be "dispersed" and may become fuzzy. The fuzziness is also controlled by the reflection sharpness of the surface material, which may be controlled in the Material Lab if it is a texture that has applied from the Material Explorer. When glossy effects are turned off, all reflections will be perfectly sharp, i.e. non-fuzzy. Having this turned on usually implies longer render time.

Glossy sampling

Increasing this value will generate less noisy reflections in the final image. It will only affect surfaces that have a material with reflection sharpness below 1.

Denoising

Denoising

Denoising can be used to reduce the noise (which can occur from lower sample sizes) in the final image at the expense of longer render time and possibly loss of detail. When a Rectangular area light has been used, or when "Use Area Light" is checked for a Florescent ceiling from the Lights extension , turning denoising on is recommended.

Denoising radius

A larger radius will increase the effect of the denoising since the graphics engine will analyze more samples to remove noise. This will result in longer render time but possibly higher quality images.

Denoising strength

If set to a higher value, the denoiser will smooth more details in the image, resulting in an image with less noise. The expense of increasing the strength is a loss of details in the original image.

Global illumination

Global illumination settings are only available when Natural light or 360° with natural light is set in Render Mode.

Global illumination

When Global illumination (GI) is turned on, the graphics engine will try to simulate indirect lighting, i.e. light that bounces off the surfaces in the scene. This is a critical feature for producing photo-realistic images.

The process of calculating indirect lighting is divided into two steps:

• Produce a GI estimate.
• Produce a GI cache.

Sampling rate

Increase this value to improve the quality of the first GI estimate. Generally though, there is no need to change this value.

Hemisphere sampling rate

Increase this value to improve the accuracy of each individual GI sample at the expense of longer render time.

Interpolation samples

Increasing this value will produce a smoother indirect lighting but it also means that more details will be lost.

Number of passes

By increasing this value, a larger number of GI samples will be created, resulting in a more accurate GI signal. Increasing this value also results in longer render time.

Error tolerance

Decrease to improve the quality of the GI cache at the expense of longer render time. The impact on the render time is quite high. Generally, it is good to avoid editing this value but it could be useful for specific rendering scenarios. If you are decreasing this value, make sure that “Hemisphere sampling rate” is increased, otherwise there is a great risk of introducing GI errors in the rendering.

Precise cache

Enable/disable the high precision computation mode for the GI cache. If enabled, small geometric details are automatically detected and captured by the GI calculation. For instance, this helps when rendering fine geometry variations like cabinet gaps, tile edges, window frames etc. Its impact on render time depends on the scene but is usually fairly low.