Octane Render Passes

Options

Octane has an additional node in the render target to add full support of render passes (or render layers), the Render Passes node. This feature makes possible export a lot of information about the rendered image as layers than can be used in the post production packages to fine tune the rendering or for composting tasks.

The render passes are rendered all at the same time while rendering the scene with F9/F10, and can be previewed in the IPR window selecting one pass from the enabled passes list.

We distinguish between Beauty, Info, Layers and Lighting passes. Beauty and Lighting passes are rendered together with the main beauty pass (the normal rendering). I.e. each one of these requires its own film buffer that needs to be stored additionally to the main film buffer on the device. The info passes are rendered one by one using only one additional film buffer either at the end or when needed. We do this to save GPU memory and because they are fast to calculate.

The Options tab details the following:

• Passes File/Prefix - Allows the user to set the Passes File Prefix name for each pass.

• File from Render Globals (toggle) - determines whether Octane Render uses the Global Prefix/filename from the Render Globals panel.

• File Format - Al;lows the user to chose which file format is used from the dropdown menu

• Name Format - Allows the user to set the name format used from the dropdown.

• EXR Compression Format - Chose the compressed EXR format used to save the files

• EXR Half Precision (toggle) - This will use 8-bit floats for the EXR format instead of 16-bit floats.

• Save OpenEXR Deep File (toggle) - Allows export of the EXR files to the OpenEXR Deep format support by OpenEXR ( part of the Academy Software Foundation).

• Save Noisy File/Layer (toggle) - This will save un-filtered (i.e. noisy) output from EXR for post-processing.

Beauty Passes

The beauty passes provide a rendered view of the different aspects lighting the scene, such as shadows, highlights, reflections, illumination and color. Beauty passes are rendered together with the main beauty pass (the normal rendering). I.e. each one of these requires its own film buffer that needs to be stored additionally to the main film buffer on the device.

The rendered passes can be saved in a layered EXR file, or as discrete PNG or EXR files (one file for each pass). In the Options tab of the Render Passes node, you can set the file path an prefix name, select the file format, the file name format and the compression algorithm used in the EXR files. There is also an option to export the floating buffers in the EXR files as half precision floats, to save storage space.

Info Passes

Info passes, on the other hand, provide a view of the effects of the normals, UVs and geometric data provided in the scene. The info passes are rendered one by one using only one additional film buffer either at the end or when needed. This is to save GPU memory and because they are fast to calculate. The maximum samples (Max samples) for Info passes can be adjusted without affecting the maximum samples set toward the final rendered image.

Info Passes:

• Geometric Normals - The vectors perpendicular to the Mesh's triangle faces.

• Shading Normals - The vectors perpendicular to the Mesh's triangle faces.

• Vertex Normals - The vectors perpendicular to the Mesh's vertices.

• Position - A color-coded image that shows the position of the objects in the scene, often used in compositing to help position 3D-rendered images from different renders.

• Z-Depth - An image that's shaded based on the distance between the objects in the scene and the rendering camera's position.

• Material ID - Every Material assigned in the scene is represented as a separate color.

• UV Coordinates - A color-coded image showing a Gradient map based on the direction of the object’s UV texture coordinates.

• Tangents - The first tangent vector. This determines the Normal map distortion's orientation.

• Wireframe - Triangles outlined in black represent the mesh.

• Motion Vector - This renders the 2D motion vector in screen space. The X-coordinate shows pixels set in motion to the right (stored in the Red channel), while the Y-coordinate shows pixels in the up motion (stored in the Green channel).

• Object ID - A color-coded image, each object is colored based on their Object ID settings. The Object ID setting is found in the Octane Attributes section in the Object’s Shape node tab.

• Ambient Occlusion - A render that's shaded using ambient occlusion calculations. Recessed areas of the surfaces are shaded darker than their surroundings.

Additional Parameters

• InfoChannel Max Samples - Sets the maximum number of samples per pixel before the rendering process stops. Higher values result in cleaner renders.

• Distributed Ray Tracing - Enables motion blur and depth of field, and sets the pixel filtering modes.

• Distributed Rays - Enables motion blur and DOF, and enables pixel filtering.

• Non-Distributed with Pixel Filtering - Disables motion blur and DOF, but leaves pixel filtering enabled.

• Non-Distributed without Pixel Filtering - Disables motion blur and DOF, and disables pixel filtering for all render AOVs except for render layer mask and ambient occlusion.

• Z Depth Max - Determines the maximum depth as shown in the shading of the Z-depth info channel pass.

• Motion Max. Speed - Speed mapped to the maximum intensity in the motion vector channel. A value of 1 specifies a maximum movement of 1 screen width in the shutter interval.

• UV Max - Sets the maximum value that Texture coordinates can show.

• UV Set - Determines the UV set number to use. LightWave supports three (3) UV sets pertaining to the first three (3) UV VMAPs.

• AO Distance - Sets the maximum spreading distance of the Ambient Occlusion shading.

• AO Alpha Shadows (toggle) - Takes the surface Opacity as determined by its shader into account when rendering using the Ambient Occlusion info channel. Ambient Occlusion shading is based on the surface opacity.

• Opacity Threshold - Sets the minimum Opacity value for surfaces when rendering with AO Alpha Shadowing enabled.

• Bump and Normal Mapping (toggle) - Enables Bump and Normal map rendering in images created with Info Channel renders.

Render Layers

Render layers allow you to separate your scene geometry into one part that you want to be visible and the rest that “captures” the side effects of the visible geometry on it.

This feature is meant for compositing and not to hide parts of the scene, for which you either would disable the object in the scene editor to not render or use the general visibility options.

As a consequence, render layers really make sense only if you enable the alpha channel in the render kernel.

The Render Layers panel

The main beauty pass will only render the current layer and cut out everything else, but the real power is in the shadow and reflection layer passes, where the “side effects” of the render layer are captured. You can use those to compose the render layer on some background and with shadows and reflections.

The new render passes are named Shadows, black shadows, Colored shadows, and Reflections. These passes only work in conjunction with the render layers. If you enable them in your project without any further configuration, you will only see empty renders for these passes. More formally, these passes capture the “effect” from geometry part of the active render layer onto geometry part of all the other render layers. The first thing that needs to be done is configure object layers for the geometry using the render layers editor panel.

During rendering, objects that aren’t on the active render layer are ignored by camera rays. This means that all objects in the active layer are isolated in the beauty pass. There is no need to isolate objects from the render via masks. The main advantage is that you can easily isolate out of focus or motion blurred objects. This is impossible with masks in some cases. If you still like to use masks and do DOF and motion blur in post, you can still render out an alpha mask of the render layer with the render layer mask info channel or render layer mask pass. Let's quickly look at an example where masks fail. When trying to mask out the blurry blue sphere, it’s impossible to avoid leaking through the yellow sphere. With render layers the yellow sphere was never in the render to begin with. You could of course render out the scene without DOF and motion blur and do them in post. But I think that with the fast render times of Octane this is a bit of an obsolete work flow in most cases.

There are several toggle buttons to enable the following to be generated for each render layer:

• Layer Shadows: This pass is there for convenience. It combines black shadows (in the alpha channel) with colored shadows (in the RGB channels) in a single image. The blend mode is multiply. It captures the same shadows as the matte material with the difference that the matte materials captures all shadows in the alpha channel and hence doesn’t keep color information.

• Layer Black Shadows: Captures black shadows, i.e points on the non-active layer geometry where light is fully blocked by objects on the active layer. If light is blocked, shadows are always captured regardless of the material that receives the shadow. It’s assumed that the object that receives the shadows has a white diffuse material. e.g. shadows cast on a polished mirror like surface would not be visible in the render but we capture them in the shadow pass anyway. This pass only uses the alpha channel and should be composed in via the normal blend mode (regular alpha blending).

• Layer Colored Shadows: Captures colored shadows cast by objects on the active layer geometry. Only objects with a specular material with fake shadows enabled can cast colored shadows. (TIP: when enabling fake shadows make sure that the kernel has alpha shadows enabled, otherwise it won’t work). This pass doesn’t have an alpha channel and should be composed in via the multiply blend mode.

• Layer Reflections: Captures light reflected off of objects on the active layer on objects on the non-active layers. This pass respects the materials so the look of the reflections really depends on the materials used.

• Layer ID:

• Layer Mask:

How to enable the layers rendering in the Render Target

The figure below shows the Layers tab in the Render Target Node Editor. There is checkbox in the render target root node options (by selecting the layers tab) panel to enable the F9/F10 layers rendering, select the layers to be rendered and the file name postfix format. Each layer is rendered to a separate file in the same rendering session, without reload or update scene to make the rendering as fast as possible. You can render all your layers using only one scene.

The Visibility Only enabled means that everything on the non-active layers is ignored. That should speed things up a bit. A limitation is that you cannot capture shadows and reflections in their respective layers.

There is a command in the Octane menu bar to open the render layers editor panel. To assign one or more objects to a layer you only need to select them and set the layer number with the “Layer for the selected objects” option. The layers information is stored in the .lws scene file, so you can use your objects in more than one scene and configure the layers for each scene without problems.

Render layers allow you to separate your scene geometry into one part that you want to be visible and the rest that “captures” the side effects of the visible geometry on it.

This feature is meant for compositing and not to hide parts of the scene, for which you either would disable the object in the scene editor to not render or use the general visibility options. As a consequence, render layers really make sense only if you enable the alpha channel in the render kernel.

Light Passes

A light pass isolates the contribution of a light source. Each light pass behaves as if all the other lights in the scene are switched off. The individual light passes can be added together to recreate the original render in post or to further adjust the individual contributions of each light during post.

The light passes available are:

• Ambient light: Captures ambient light either from the sky in a daylight environment or from the texture in a textured environment.

• Sunlight: Captures the light contribution of the sun. Only useful when a daylight environment is configured.

• Light pass 1-8: Light passes 1 to 8 capture the contribution from mesh emitters. Emitters (both texture and blackbody) have a light pass ID pin assigning an emitter to a light pass. It’s possible to assign multiple emitters to the same light pass. If nothing is configured, all emitters contribute to light pass 1.

To use light passes in OctaneRender, each light emitter needs to be identified and mapped to the desired light pass. This can be done with the LightPass ID parameter available in the Octane light. This also can be done by assigning the Light Pass ID in each of the emission nodes that are in the scene.

Each light pass contributes to the main render, as shown in the figure below:

Material Passes

Octane can output material component passes for post-processing/compositing.

You can save the following:

• Opacity Component

• Roughness Component

• IOR Component

• Diffuse Component

• Reflection Component

• Refraction Component

• Transmission Component

Denoiser

Applies the OctaneRender denoiser to the selected AOVs allowing the output of explicit de-noises AOVs for shading components. The options are listed below:

• Direct Diffuse Shading (toggle) - Outputs only the single bounce direct of the scene. No indirect contribution.

• Indirect Diffuse Shading (toggle) - Outputs only indirectly-shaded diffuse pixels within the scene.

• Direct Reflection Shading (toggle) - Outputs only those pixels that receive reflections in the scene.

• Direct Refraction Shading (toggle) - Outputs any pixels receiving refractions in the scene.

• Direct Emission Shading (toggle) - Outputs any light source or light-contributing pixels of the scene.

• Volume (toggle) - The volume AOV contains all samples that are scattered in a volume.

• Volume Emission (toggle) The volume emission AOV contains all of the samples where the camera ray hit a volume emitter.

• Remainder (toggle) - Anything not explicitly selected above.

Cryptomattes

The Cryptomatte AOVs work with the Direct Light and Path Tracing kernels to render Cryptomattes for use in compositing. They are rendered one at a time, and they contain the masks for all object layers or materials in a scene. The masks also have correct anti-aliasing, and they take into account other features such as motion blur, transparency, and depth-of-field.

• Cryptomatte Channels (Slider) - The amount of Cryptomatte channels to allocated. This value must be a multiple of two, as the ID channel and coverage channel must be kept together. When a render starts, Octane collects a number of seed samples, which calculate a Cryptomatte channel distribution. These sets of channels characterize the pixel samples' properties.

• Cryptomatte Seed Factor (Slider) - This is the number of samples to use for seeding Cryptomatte. This value gets multiplied by the number of channels specified. This is important, as this value determines the precision of the Crypomatte pixels. For example, if you have several objects potentially occupying the same pixel, and any (or all) of those objects are in motion, you may see artifacts if the channel value is either too low or too high. Low values will result in pitting artifacts at feathered edges, while large values result in artifacts in places with coverage for lots of different IDs.

note

Ensure that you are using the OpenEXR format within Octane otherwise the function will not work

Octane can generate Cryptomatte AOVs according to the following IDs:

• Instance/Object ID - The Cryptomatte channel is based on distinct Object or Instance ID.

• Material Node Name - The Cryptomatte channel is based on the names of the existing Material nodes in the scene.

• Material Pin Name - The Cryptomatte channel is based on the names of the existing Material pins in the scene.

• MaterialNode - The Cryptomatte channel is based on distinct Material nodes.

• Object Node - The Cryptomatte channel is based on distinct Object nodes.