This topic shows you how to build a simple example of an Octane scene in Houdini.
Create the Octane Render Output
Once the Octane plugin has been installed and activated, start Houdini and add the Octane ROP (Render Output). In the Houdini network editor, go to Outputs and create an Octane ROP. You can also add the Octane ROP from the Octane shelf.
The Octane ROP node is the core of the Octane plugin. In the ROP node, you can set the cameras and the render target to be used for rendering including all the output options and some other render settings. Currently, you only can have one Octane ROP node in the scene.
Create the Octane Render Target
The RenderTarget is the node that is referenced as an output point for the rendered scene. It offers powerful flexibility especially when setting up advanced scenes as it hooks up to everything that forms part of the scene including the geometry, materials, environment, camera, and the render kernel – literally everything required to produce a final image. Having several RenderTargets allows the possibility to have several scene configurations of which one can be treated as the final configuration for a render.
You can build the render target adding an Octane SHOP network node and linking the render target VOP nodes to the render target output.
But the Octane for Houdini plugin has a custom digital asset that includes all the render target nodes. This node exposes all the render target features in a custom properties panel. For a lot of projects, you can control all the Octane render properties from this HDA without build a custom Octane render target node tree. You can also add this render target HDA using the Octane shelf
You need to set the render target that is going to be used for rendering in the Octane ROP node.
Add a camera
To render the scene, you will need to create a camera from the yellow box in the top right of the viewport, and set this camera node in the render and/or IPR parameter of the Octane ROP.
Houdini is now ready to render with Octane. Easy !!!
Create some geometry
We are going to create some geometry to test the Octane rendering. Add a grid to act as a floor, a cube and a sphere to the scene.
The default Houdini Sphere is a primitive that must be tessellated to be used in Octane. To tessellate an object select it, add the Octane Object Properties spare parameters using the option available in the Octane shelf and enable the tessellation in the Tessellation Tab
Adding Octane materials
Go to the SHOP context and add an Octane material. You can chose from three basic Octane materials (Diffuse, Glossy and Specular) for simple scenes or build your own material inside the Octane Network vopnet. For the floor add a Glossy material and change the diffuse color to orange. To assign the shader, drag the material node from the SHOP onto the grid geometry or select it from the material parameter of the grid object.
For the cube object we are going to build a Octane shader network. Go to the SHOP and create an Octane Network node. Double click in this material to enter in the VEX builder, where the Octane VOP nodes can be connected together to create networks. You have all the Octane nodes in the Custom tab. Add an Octane Diffuse material node and connect it to the material input in the Material Output node. Add a RGB texture node, select a texture file in the node parameters and link it to the diffuse input of the Diffuse Material. Finally add a Box Projection node and link it to the projection input of the Texture node. Assign the shader to the cube object.
For the sphere object we are going to build another Octane Network. Create a new Octane Network node in SHOP context and build a Octane material with a mix of one Glossy and one Specular material nodes, using the Materials mixer node. Assign this new shader to the sphere object.
The IPR window
We are ready to render our first Octane scene. Go to the Octane Shelf and click over the IPR button (you can also open the IPR window from the Octane ROP node). The IPR window is the core of the Octane interactive renderer. You can zoom and pan over the image with mouse buttons and wheel, reload the scene after a change, select the render passes or layers, or pick the focus point or the material under the cursor.
Edit the rendering parameters
Near all the rendering parameters can be adjusted from the Render Target node, with real time preview in the IPR window. For example we can change the rendering kernel from the default one to a full Path Tracing, change the daylight settings, the output tone mapping or the post effects.
The default lighting inside the Render Target is the daylight model, but it is easy to change it for Image Based Lighting using an HDRI texture map. Select the Texture environment mode in the Render Target Main tab and add the HDRI image in the TEXT Environment tab.
In Octane you can also use any object as light emitter to build your own light sources. You can build a light emitter using an Octane emission material for the object, or easier, use the Light Emission parameters that you can find in the Octane Object Properties spare parameters. To test the light emission, first set the TEXT Environment Power parameter to 0.2 in the last scene to dim the environment light, select the cube object and add to it the Octane Object Properties using the Octane shelf option.
In the Light Emission tab enable the light emission and play with the light parameters, like the light temperature or RGB color, the light power, etc.
Render the scene
When you have the scene ready, you can set the final render settings in the Octane ROP node and render the scene to the MPlay and/or to PNG or EXR multilayer files. In the ROP node you can also adjust the network rendering options to use the Octane native network rendering.