Irradiance Cache (Legacy) (CineRender Global Illumination)

These settings are available, as part of the optional Global Illumination effect, in the Detailed view of PhotoRendering Settings for the CineRender engine.
Least Squares: This function essentially calculates a curve based on a limited number of points.
Delaunay: In contrast to the Least Squares interpolation method, only neighboring records and not those located further away will be included in the interpolation for rendering. However, in order to achieve homogeneous dispersion of light, the Record Density, a.k.a. shading point density, should be very high. The Record Density parameter offers several Delaunay preset options that can be used for this purpose (see Record Density, below).
None: If this option is selected, no smoothing will take place.
Weighted Average: This method of interpolation works similarly to the Least Squares method, except that it only interpolates between values (whereas the Least Squares method can also extrapolate, i.e. for brighter or darker results than those represented by the defined values). This method can prevent artifacting when using low-quality GI settings. Furthermore, this method will render faster than the Least Squares method. Disadvantage: The dispersion of light is less homogeneous than when using the Least Squares method.
Method: This parameter contains a set of predefined parameters that are by default optimized for most uses. Only under special circumstances should you change the option to Custom and modify these parameters yourself.
Preview: As the name suggests, a preview will be rendered quickly – with correspondingly “poor” values that make a quick rendering possible. These “poor” values will result in many GI details being lost or in faulty rendering.
Low/Medium/High/High (Details): These four options are optimized for use with the Least Squares interpolation method and result in differing levels of quality.
Low (Delaunay)/Medium (Delaunay)/High (Delaunay): These three options are designed for use with the Delauney interpolation method. This interpolation method requires a very dense dispersion of shading points.
Method: Use the pop-up to define the level of smoothing. Select Custom to manually define the Records and Scale values below.
Records: The Records parameter defines, for each pixel to be rendered, the maximum number of surrounding Records in the Irradiance Cache that should be included in the interpolation of color and brightness for that pixel. If, however, the Scale value is so low that not enough Records can be included in the interpolation, it may result in fewer Records being included.
Scale: This parameter serves to spatially limit the Records included in the interpolation process. The larger the value, the more Records will be included and the softer the interpolation will be – and the longer it will take to render. Alternatively the Records parameter can be used for this purpose.
Tip: Refining the cache can greatly increase the number of Records in the Irradiance Cache, which will not necessarily improve the render quality. Especially when applied in conjunction with incorrect smoothing, this can lead to very grainy results. Hence, only refine the cache if absolutely necessary.
Passes [0..4]: Use this setting to set the frequency with which the cache should be defined. Each new pass includes the results of the previous pass and refines it further by creating additional shading points in critical areas.
Color Threshold: This value defines the degree to which (neighboring) cache Records can deviate from each other with regard to their color (intensity) before additional shading points (“Samples”) are added. The lower the value, the lower the deviation threshold will be and the more samples will be added.
Cutoff: This value includes differences in intensity. The lower the value, the greater the differences between Records have to be for the color correction to apply. A value of 0 will turn cache refinement off.
Strength: This parameter is used to adjust the cache refinement’s overall sample density. A value of 0 will turn cache refinement off, whereas larger values will increase the number of shading points (“Samples”) correspondingly while taking into account Color Threshold and Cutoff values.
Details Enhancement: Check this box to enable the Details Enhancement parameter.
Adaptive: Enabling this option can be an advantage in some circumstances, e.g. several small areas are more grainy than others. Additional samples will then be rendered in these areas.
Estimate Secondary: This mode renders faster and offers good results for most applications. However, certain areas will be rendered too dark or too colorful as opposed to a pure QMC rendering (GI Mode QMC), which in most cases doesn’t matter at all. If desired, this behavior can also be disabled (note that grainy renderings can result, in which case the Quality Ratio value should be raised).
Radius: Use this setting to define the radius within which neighboring objects, corners and edges should be included. Lower values result in only elements in the immediate proximity being “seen”, whereas larger values will “see” elements correspondingly far away. Larger values will also result in higher precision and therefore longer render times.
Quality Ratio: As mentioned, QMC Sampling will take place in critical areas. The Quality Ratio defines how many samples should be used per pixel, which in turn simply defines the graininess of the Details Enhancement. Larger values result in less grainy, softer results but require correspondingly longer render times.
Mode: The options in this drop-down menu are for test purposes only so the effects of the detail enhancement, which are often very subtle, can be made more visible. You can select from the following options:
Combine (Normal): Renders accurate results.
Details Only (Preview): Renders detail enhancement without GI. Makes the detail enhancement the most visible of all the options.
Global Only (Preview): Renders indirect illumination only.
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