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AOV
Indicates what variable will be output during this render. The most common values are ‘rgba’ or ‘rgb’ for RGBA and RGB outputs respectively, which are usually referred as "beauty passes". You can specify here any predefined output variable or arbitrary output variables that your shaders are using. Inline declarations of arbitrary output variables are allowed, meaning that it is permitted to preceded a variable name with its type to declare it and specify it for the display mode all at once. Right-clicking Clicking on the arrow button next to the AOV text field brings up a popup menu that lists available predefined output variables.
The available values that are relevant regardless of the shaders assigned of to scene elements are:
| AOV | Description |
|---|---|
| user specified | This item is selected when a custom variable name is typed in the text field. |
| z [depth] | For a given pixel, this variable outputs the distance between the camera and the object visible at this pixel. Bit depth should de set to 32 bits. |
| rgb [color] | This variable outputs the color information of the rendered image. |
| ‘a [alpha channel]’ | This variable outputs the transparency information of the rendered image. |
‘Oi [3-channel alpha]’ | This variable outputs the R, G and B transparency information of the rendered image. |
‘rgba [color + alpha]’ | This variable outputs the color and transparency information of the rendered image. This is also called a beauty render pass. This is the default. |
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Chapter 3: The User Interface 59
sponds to a quantization of 0, 0, 0, 0, and a dither value of 0 (identical to ‘32 bit float’); the display driver receives a pixel type specification through an option.
‘32 bit float’
The image will use 32 bits float values for each color component. This corresponds to a quantization of 0, 0, 0, 0, and a dither value of 0.
‘Custom...’
All images are rendered internally in 32-bits float format. Quantization is the process of assigning integer values to these floating-point values. Some usual preset values are available in the "Bit Depth" attribute. If they do not include the needed variation, it is possible to specify custom quantization values by selecting this menu entry. Upon selection, a dialog pops up. It allows specification of values for zero, one, min, max and dither amplitude. zero is the black point, while one is the white point. These two values can be different from the min and max values if you need to have under-exposed or over-exposed values. An example set of values for 12 bits output with standard dithering would be: 0, 4095, 0, 4095, 0.5 An example set of values for 16 bits output with a white point at 4K that prevents over-exposed pixels from being clamped to the white value, would be: 0, 4095, 0, 65535, 0.5
‘Other Custom entries’
The option menu will also list all custom bit depths defined for all of the current render pass’ displays.
Some display drivers have specific requirements as to what bit depths are supported. Refer to [Display Driver], page 54.
A specific display's Advanced group
The Advanced group, which is collapsed by default, offers the following attributes:
Alternate Camera
This attribute can be used to specify a different camera than the Render Camera (specified in the Scene Elements group) to be used for this display. This allows simultaneous multi-camera angle or stereoscopic rendering. For best performance, it is recommended to keep as many displays as possible set to <render camera>. For instance, when working with a stereoscopic project that has a "left eye" camera and a "right eye" camera, it is preferable to set the Scene Elements' Render Camera to the "left eye" camera, and alter the value of the display's Alternate Camera only for the ones needed the "right eye" camera (instead of having all displays overriding the render camera with either the "left eye" or the "right eye" camera). By default, the display will use the Render Camera.
Display Subset
This attribute is used to select one or several Maya sets that is used to narrow down what objects will appear in the display. Set selection is made using the 3Delight Set Selector window which is invoked by clicking on the Sets... button. The "Display Subset" option menu specify how the selected sets will be interpreted and has the following values available:
| Option | Description |
|---|---|
| All Objects | All visible objects will appear in the display, disregarding any sets selec- tion made in the 3Delight Set Selector. This is the default. |
| Objects in selected sets | Only visible objects in the selected Maya sets will appear in the display. |
| Objects not in selected sets | Only visible objects that are not in the selected Maya sets will appear in the display. Put differently, all objects in the selected sets will be excluded from the display. |
Light Category
This attribute specifies a light category (see Category); only the lights of this category will appear in the display. This option requires setting the Render Engine attribute to Path Tracer (see Render Engine).
Gain
Specifies the gain. Each rendered pixel’s color will be multiplied by this value. ‘Gamma’ Specifies the gamma. Each rendered pixel’s color, once affected by "Gain", goes through a power function whose exponent is 1 / "Gamma".
Override Pixel Filter
Each display can have its own filter and filter width values. This toggle is off by default, in which case the display will use the values specified in the Quality section of the render pass. When this toggle is on, these values are overridden with the values specified in the following two attributes: ‘Pixel Filter’ ‘Filter Width’ These two attributes are identical to the "Pixel Filter" and "Pixel Filter Width" in Quality - Render Pass(Rendering Attributes).
Use Matte Attribute
When this toggle is off, and if the display’s output variable is set to an arbitrary output variable, any matte attribute set on objects will be ignored. This toggle is on by default. Refer to the matte attribute here Visibility.
Exclusive Output
When this toggle is off, and if the display’s output variable is set to an arbitrary output variable, objects that do not output that variable will be black. Turning this option on will make these objects transparent. This toggle is off by default.
Associate Alpha
When this toggle is off, the color of a pixel is divided by the alpha to produce an image with an unassociated alpha channel. By default, this toggle is on.
Compute Alpha
When this attribute is on and the display’s "Output Variable" is an AOV, an alpha channel is added to the AOV. It is computed based on the existence of the output variable for a given object. This toggle is off by default. Usually, when this toggle is on, it is recommended to turn off Associate Alpha.
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