Outputs

#Introduction# What is output?

As the computer program use numbers to paint images the resulting color for each pixel can be observed in a viewing program as well as stored in an image format. This may be the combined and expected result of the many various calculations. It is also possible to allow more flexible and precise control over image adjustments after initial rendering. This is done by additionally storing selected numbers from the image calculation process. These may be standard passes or any arbitrary output variables.

An Interactive Rendering mode is also available, and is used to allow previewing and some interactive control over the expected output. While the interactive mode uses the same rendering engine and sampling settings as the final render, the need to keep the session responsive typically means lowering the quality settings to the point where the image would not be usable as an actual output.

####Available Outputs####

• It
• Automatically composited file(s)
• Passes
• AOVs

####Wordlist#### diffuse, a dull material surface. A layer of material characteristics that does not depend on the position of the observer.
indirect, the effect on a material based on one or more bounces of illumination.
specular, a shiny reflective surface and/or transparent refractive material like glass or water. A layer of material properties that significantly depend on the position of the camera.

#Output# Properties > Render > Output

####Display Driver#### It, a specialized viewing software.
TIFF, a standard image data container (format).
OpenEXR, an standard image container (format) that supports High Dynamic Range values.

Display Image, example: "$OUT/images/{blend}_####.{file_type}". The identifier "$OUT" is set in the Add-on Preferences at Info Editor > User Preferences > Add-ons > Render: PRMan Render Engine > Preferences. "/images/" will organize the images in this folder. The identifier {blend} will automatically be replaced with the current matching blender filename. The number tags "####" are filled in with different frame numbers allowing an animation to be rendered as an image sequence. Finally, by using ".{file_type}" the correct suffix according to chosen Display Driver will be automatically set.

Recommendation for projects: Projects may be organized in folders and blender files stored in a subfolder called blend. With OUT (Output Root) set to "//../" each project path will be automatically changed relative to the current blender file. Additionally, Save Versions set to 32 automatically keeps track of file iterations during production and can be very helpful when troubleshooting. It is found in Info > File > User Preferences > File. This safer approach to production require a project folder and a blend subfolder to avoid an inconvenient mess of files. A "Default" project folder with a "blend" subfolder is practical for simple tests.

Denoise Post-Process (enable/disable), a specialized post process feature used to selectively and brutally reduce certain noise in the end of a rendering process.
Helpful Tip: if you are running the render from inside Blender, you should select the 'IT' output to use the denoiser. Due to the way Renderman feeds images back to Blender, use of the denoiser and any other option from within Blender will cause a significant slowdown that will outweigh any advantages. If you select the 'IT' output the image is not fed back into Blender and this issue is avoided.
Weaknesses: The denoiser is not a magic pill for removing noise, and if it is used with extremely grainy images artifacting can occur. For best results an image should be rendered to relatively high quality and the denoiser used to remove the last traces of noise.

#Passes# Properties > Render Layers

Combined, an automatically composited image.
Z, depth values.
Normal, directions of normal (as seen through camera).
Vector, directions and speed of motion. (?)
UV, values from UV-coordinates. (?)
Object Index, values specified in Properties > Object > Relations > Pass Index. (?)
Diffuse Direct, dull light without any bouncing.
Diffuse Indirect, dull bounced light.
Diffuse Albedo, underlying color of dull materials with no lighting effects applied.
Specular Direct, reflections and refractions of light without any bouncing.
Specular Indirect, reflections and refractions of light when bounced.
Subsurface, effect of light scattered beneath a surface.
Refraction, light transmitted through a surface that causes a change in index of refraction (glass).
Emission, effect of illuminating sources prior to bounces.

##AOVs## Properties > Render Layers > RenderMan AOVs

AOVs (Arbitrary Output Variables) Plus, used to add a channel. Minus, used to remove selected channel.
Channel Name, used to arbitrarily label a channel.

####Channel Type#### Refraction, displays light transmitted through a refractive surface.
Subsurface, displays light scattered beneath a surface.
Indirectspecular, displays the indirect illumination from a specular object. Identical to Reflection AOV.
Specular, displays the illumination that hits a specular object directly from a light source without bounce lighting.
Indirectdiffuse, displays the indirect illumination from a diffuse object.
Diffuse, displays the illumination that hits a diffuse object directly from a light source without bounce lighting.
Reflection, displays the illumination bounced off a reflective (specular) object. It is identical to IndirectSpecular AOV.
Shadows, displays a grayscale image of the shadows cast in the scene.
Caustics, displays reflected and refracted light projected towards receiving (diffuse) surfaces.
Custom, a customized AOV that can contain any combination of passes.

LPE String (string). Box used to enter custom lpe (light path expression) variables and arguments. NOTE: custom lpe's are a potentially confusing but powerful advanced feature. Please see the 'Lpe's for Dummies' tutorial if you are feeling adventurous.

####Advanced#### LPE Group (string). A holdout group name can be entered here. Only the objects in this group will appear in the AOV.
LPE Light Group (string). A light group name can be entered here. Only illumination from this group will appear in the AOV.