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Render Outputs


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Rendering is the act of converting the scene information into a bitmap image by evaluating all the geometry and lighting information in a given file. Generally users will expect the resulting rendered image to be a fully ray traced and shaded image with full shadows, reflection and the like, much like a photograph depicts an entire scene when taking a picture with a camera. In modo these images are the result of what are called "Render Outputs", the visible representations of the full scene evaluations. Each Render Output is a separate layer in the Shader Tree and will produce its own image layer as part of the render calculations. Every time a Render command is invoked, all of the render output layers are simultaneously calculated and represented in the Render Display viewport. The different layers can be viewed by choosing one of the specific 'Output' options within the display window.

Occasionally users will only want a subset of the full evaluations, such as the diffuse color layers without any shadows. modo offers many different 'Render Output' types useful in a variety of situations ranging from purely diagnostic, to specific compositing utility in an external application. A default scene automatically includes a 'Final Color' and 'Alpha' output which should be fine for most situations. Additional layers can be added from within the shader tree viewport itself, by LMB-clicking the 'Add Layer' option of the full viewport window and selecting "Special >> Render Output" from the pop-up menu. This adds an additional layer to the top of the tree. Users may then RMB-click in the 'Effect' column of the Render Output for a pop-up context menu that allows one to select from the alternate output types. Please reference the primary Render Outputs page of the documentation listed under the Shader Tree Layers section for for information regarding the editable attributes of the individual outputs. The various output types available are as follows--

Alpha
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The 'Alpha' output will calculate the opacity of the objects based on their material settings to determine an alpha (transparency) value. With this setting, environment colors and textures will not contribute to the alpha channel, so that when you view the final image with an application that supports alpha channels, only the rendered geometry will be visible. If an object or surface has a level of transparency this will also be considered in the alpha channel. In this way it is possible to render out images with semi-transparent elements that can easily be composited over other backdrops in an application such as Shake, Motion or Photoshop. For best results when compositing multiple images, you should enable 'Unpremultiply Colors' in the corresponding 'Final Color' output.

Ambient Occlusion
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The 'Ambient Occlusion' output generates an occlusion map where occluded areas; crevices and other inaccessible areas of a scene shade darker, while open areas render lighter colors, approximating an overall global illumination type of shading. Grainy renders can be smoothed out by increasing the 'Occlusion Rays' value, controlling the density of the occluded areas is done through the 'Occlusion Range'. Reference the 'Ambient Occlusion' section on the alternate Render Output page for more information.

Depth
Depth Output
The 'Depth' output generates a Z-Buffer that represents the distance from the camera to the geometric surface in shades of gray. Rays begin white at the ray origin (camera position) and attenuate darker as they get longer becoming fully black at the specified 'Maximum Depth' value. Useful for calculating Depth of Field in an external application or for composing a fog effect into a rendered scene.

Diffuse Coefficient
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The 'Diffuse Coefficient' output renders the diffuse colors of a scene independent of illumination or shading.

Diffuse Shading (Direct)
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The 'Diffuse Shading (Direct)' output renders a channel of the diffuse color and shading of all objects in scene by all direct light sources independent of other surfacing attribute. Basically a combination of diffuse coefficient and direct illumination.

Diffuse Shading (Indirect)
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The 'Diffuse Shading (Indirect)' output renders a channel of the diffuse shading of all objects in scene by all indirect light sources independent of other surfacing attribute. Basically a combination of diffuse coefficient and indirect illumination.

Diffuse Shading (Total)
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The 'Diffuse Shading (Total)' output renders a channel of the diffuse color and shading of all objects in a scene by all light sources, independent of other surfacing attribute.

Diffuse Shading (Unshadowed)
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The 'Diffuse Shading (Unshadowed)' output renders a channel of the diffuse color and shading of all objects in a scene by all light sources, independent of other surfacing attribute while excluding shadows cast by direct and indirect lights sources.

dPdu Vector
Dpdu Vector
The 'dPdu' and 'dPdv' are world space vectors that point in the direction of increasing U and increasing V at each point on a surface that has a UV map. dPdu and dPdv have a big effect on the anti-aliasing of UV image maps and also define the reference directions for anisotropic highlights and reflections, so the outputs are sometimes useful for the purposes of debugging.

Dpdv Vector
Dpdv Vector
The 'dPdu' and 'dPdv' are world space vectors that point in the direction of increasing U and increasing V at each point on a surface that has a UV map. dPdu and dPdv have a big effect on the antialiasing of UV image maps and also define the reference directions for anisotropic highlights and reflections, so the outputs are sometimes useful for the purposes of debugging.

Final Color
Final Color
The 'Final Color' output represents the settings of the shader tree, leveraging all visible material and texture layers as well as shaders and the render item settings.

Geometric Normal
Geometric Normal
The 'Geometric Normal' output simply renders all meshes with a color ramp based on the angle of their polygonal normal. It is useful for evaluating the continuity of a mesh's surface. In this example smoothing has been disabled.

IC Positions
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The settings within the 'Render Item > Properties > Global Illumination' tab allow you to specify values that the Irradiance Cache uses to shade a rendered scene. The 'IC Positions' output will display the pixel positions used in generating the shading based on the Irradiance Cache values. Green points are positions sampled during the initial pass, Red points signify additional sample generated by the Interpolation Values setting. Useful in analyzing various IC settings.

IC Values
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The settings within the Render Item > Properties > Global Illumination Tab allow you to specify values that the Irradiance Cache uses to shade a rendered scene. The 'IC Values' output will display the diffuse values calculated during the initial irradiance cache render pass. The image will appear splotchy as each irradiance sample is not blended with nearby samples; giving one a much better understanding of the area affected by individual IC positions. Useful in analyzing various IC settings.

Illumination (Direct)
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The 'Illumination (Direct)' output generates a channel exclusive to the illumination in a scene from all direct light items such as distant lights, area lights, point lights and spot lights, independent of all other surfacing attributes.

Illumination (Indirect)
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The 'Illumination (Indirect)' output generates a channel exclusive to the illumination in a scene from all indirect sources such as image based lighting and luminous polygons, independent of all other surfacing attributes.

Illumination (Total)
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The 'Illumination (Total)' output generates a channel of the full illumination in a scene including shadows cast by direct sources, independent of all other surfacing attributes.

Illumination (Unshadowed)
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The 'Illumination (Unshadowed)' output generates a channel of the full illumination in a scene excluding shadows cast by direct sources, independent of all other surfacing attributes.

Luminous Shading
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The 'Luminous Shading' output generates a channel of all the luminous shading within a scene independent of all other attributes.

Motion Vector
Motion Vector
The 'Motion Vector' output encodes the direction and speed of each pixel into an RGB value, which can then be further processed in an external application to apply motion blur to a rendered image as a post production effect. This can greatly enhance the smoothness of motion blur and save rendering time when processed this way, however, since each pixel can only have a single color value (and therefore a single motion vector), incorrect result will be produced when motion blurring transparent or translucent objects moving in a scene.

Object Coordinates
Motion Vector
The 'Object Coordinates' output generates red, green, and blue components that contain the undeformed object space X, Y, and Z coordinates of visible surfaces. The pixel values are in meters and can be negative, so a floating point image format should be used when saving this output. This theoretically allows postprocessing applications to add solid textures that will remain attached to surfaces during an animation.

Reflection Coefficient
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The 'Reflection Coefficient' output renders a scene as grayscale image that represents the reflection amount per surface. Black for 0% reflectivity ramping toward white at 100%.

Reflection Occlusion
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The 'Reflection Occlusion' output renders a channel that is strictly black and white, determining if a reflection ray off of an object has hit any other geometry in the scene. White if it has and black if it has not. The areas that appear as white here would be shaded with the background environment in a Final Color render.

Reflection Shading
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The 'Reflection Shading' output generates a channel of all the reflection calculated within a scene independent of all other attributes.

Segment ID
SegmentID
When modo renders a project, all meshes are broken down into "segments" for reasons of optimization and general scene management. Using the 'Segment ID' shading option will render each generated segment with a random color. This shading method is purely a diagnostic option.

Shaded AA Samples
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The 'Shaded AA Samples' output shows the fraction of Antialiasing samples in each pixel that were actually shaded, using a color scale ranging from blue (one sample shaded) to red (all samples shaded). This approximates the shading cost per pixel and can be used to diagnose issues related to shading rates and the refinement threshold.

Shading Incidence
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The 'Shading Incidence' output renders a grey scale image the represents surfaces angle relative to the camera. Shaded surfaces that face directly at the camera are rendered as black attenuating toward white on shading that is perpendicular to the camera.

Shading Normal
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The 'Shading Normal' output renders all meshes with a color ramp based on the angle of their surfaces shaded normal. Where the geometric normal is calculated exclusively by the polygonal geometry, the shading normal also takes in to account surfacing attributes affect on normals such as bump maps.

Shadow Density
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The 'Shadow Density' rendering output renders a channel generated from the density of all direct light shadows in modo exclusive of color shading or texture. The darkest areas of shadow render as white white ramping toward black for the areas that would be fully illuminated. When rendering in layers, it is very useful to have shadows rendered separately giving one control of color and transparency. You could easily invert this channel in an image editing application and layer it over the unshadowed render set to 'multiply', giving control over how dark the shadows are based on the layers transparency.

Specular Coefficient
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The 'Specular Coefficient' output renders a grayscale image that represents the amount of specular on surfaces within a scene. Black for 0% Specularity ramping toward white at 100% Specular.

Specular Shading
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The 'Specular Shading' output generates a channel of all the specular shading within a scene independent of all other attributes.

Subsurface Shading
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The 'Subsurface Shading' output generates a channel of all the subsurface scattering shading within a scene independent of all other attributes.

Surface ID
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The 'Surface ID' output render each material with a random color. This is purely a diagnostic shading option, as it may be helpful in spotting surface relationships in complex scenes.

Transparent Shading
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The 'Transparent Shading' output generates a channel of all the Transparent shading within a scene independent of all other attributes.

UV Coordinates
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The 'UV Coordinates' output generates a channel that converts UV positions to a color value. Some software is then capable of utilizing this image to reapply a texture map to the object after it has been rendered.

Volumetric Depth
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Volumetric Items are not evaluated for all render outputs items, such as Depth, so the 'Volumetric Depth' option allows users calculate depth values for volumetric items in the scene. Note that each pixel in the volume can only have single depth value, so opacity is not considered for this type of output.

Volumetric Opacity
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The 'Volumetric Opacity' output evaluates the transparency of the volumetric elements in the scene allowing users to separate the opacity of the volume independent of the rest of the scenes elements for compositing.

Volumetric Scattering
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The Volumetric Scattering render output will render only the volumetric elements of any scene, including those generated by 'Sprites', 'Volumes' and 'Volumetric Lights'.

World Coordinates
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The 'World Coordinates' output generates red, green, and blue components producing the final world space X, Y, and Z coordinates of visible surfaces. The pixel values are in meters and can be negative, so a floating point image format should be used when saving this output.

 

Compositing Outputs

Render output are incredibly useful when users wish to compose the generated layers individually in an external application, such as Photoshop, After Effects, Nuke or Fusion. This can aid in tweaking color, among other settings as a post process without requiring additional render time. The question most often asked is "Which Render Outputs combine to equal the Final Color output?" The answer is "Diffuse Shading (Total) + Transparent Shading + Reflection Shading + Specular Shading + Subsurface Shading + Luminous Shading = Final Color", where each successive layer is added to the layer below in the composition (also called Linear Dodge). Rendering each layer at a gamma of 1.0 and then combining them and adding the gamma back to the fully composed layers will produce the best results.

Users may also render out simultaneous alpha channels for each item in a scene by creating item masks for each and placing a render output set to Effect > Alpha (or simply adding them to existing Shader Tree masks). Then each time a render command is invoked, all active (visible) render outputs will be generated simultaneously.

Render Outputs COmp

 

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Kernit The Font December 30, 2013 at 3:28 AM

A useful mnemonic for the compositing order of render Passes is:<br><br>Don't Try Red Spinach (for) Sunday Lunch<br><br>(Diffuse, Transparent, Reflection, Specular, Subsurface, Luminous)

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