This tutorial was written by the amazing Rainer Duda and appeared in issue 104 of 3D Artist
The Foundry’s KATANA, in conjunction with the famous 3Delight renderer, are key players when it comes to lighting, shading, look development and rendering for professional movie productions and top-notch commercials. In this tutorial you will learn how to import widely used alembic files – which are figuratively the root for professional asset-based workflows – and how to set up a project to render a final image.
During this journey you will discover how the Node Graph – KATANA’s core working area – must be used and how the actual data flow is represented. The next major workflow you will learn is for asset behaviour. To control the behaviour of objects in a KATANA project, you must leave the Node Graph and change the asset influence in different contexts through the so-called Scene Graph editor, which can be seen as a file explorer with hierarchies. The general concept underlying both work areas and the interaction from Node Graph to Scene Graph with dataflow will be easier after this tutorial.
Step 01 – Start a basic scene setup
At first we must create the scene including the hero assets followed by a render camera. Jump to the Node Graph and open the Node menu through the Tab key on the keyboard – an alternative would be to use the right mouse button. By typing the first letters of a node it will jump to the respective place in the list. We need the following nodes: Camera Create, Alembic In and a Merge node. Both transforms will be used to place the hero asset in the scene. We must expand all branches in the Scene Graph window. Only expanded branches will be shown in the viewer and monitor.
Step 02 – Place the camera in position
With a simple shaded asset it is already possible to adjust the final camera position. Just jump to the Viewer widget and look through the camera to find a suitable-looking position. The necessary function lies in the centre just below the Perspective view. Unfortunately the output image is still square-shaped. In order to change that, we must append a Render Settings node. In the corresponding attributes, choose HD for the Resolution and activate a function called Adjust Width To Match Resolution. Now the image takes HD 1080p picture information as the global output for rendering.
Step 03 – Work on a proper render output
Before the render image can be seen in the viewer or in the 3Delight framebuffer, there must be at least two more nodes appended. The first of these two necessary nodes is a DlSettings node followed by a Render node. The first is responsible for choosing the Anti-aliasing Filter method. In this case we must use Blackman-harris with a Filter Width of 3 pixels. In addition to this, it is necessary to say what kind of framebuffer should be used. In this workshop we’ve stayed in KATANA and haven’t used 3Delight’s framebuffer. We must choose KATANA’s monitor. The Render node enables rendering in passes and on a farm.
Step 04 – Let there be light
Before we start working on the materials themselves, it is time to create some basic light sources for a better look in the preview renders. After the Merge node we must append a so-called Gaffer Three node. This node is highly optimised and can hold a large variety of direct and indirect light sources at once. In there we must create two area lights, one with a warm tint and the other with a cooler light-blue tint. The warmer colour will be the main light, which is sending light from the left-hand side, while the cooler light comes from the back on the right-hand corner.
Step 05 – Set up basic materials
Now we’ve reached the stage where it’s time to work on the materials. There are plenty of ways to create materials in KATANA. In this workshop we’ve jumped back on the top of our network and we’ve create four DlShadingNode objects followed by four Network Material nodes, one for gold, crystal, red SSS and a material for the desk. Feel free to create crystal-coloured variations. The Network Material nodes will obey a material supplier by giving them a so-called Dl Surface Terminal, which is nothing more than a connector to input the colour out from the DlShadingNode objects.
Step 06 – Assign the materials for adjustment
The basic materials are in place but still not assigned, and that will be our next step. Directly after the Merge node we must append four Material Assign nodes from the Node menu. Each Material Assign node consists of two blocks. In the Material Assign block we must take the corresponding material from the Scene Graph and drag and drop it with the middle mouse button into the Material Assign field. In the upper area we’ll want to keep it simple with a path function in the CEL field. In this field goes the geometry that needs to have the material assigned. Repeat this step for all materials.
Step 07 – Tweak the materials
Creating a Shading node followed by a Terminal only gives us a material template. Now it is time to create real materials. In order to do this, we must go back to each individual DlShadingNode object. In the Attributes we must set a Correct Node type. By using the drop-down menu we are able to choose between predefined Material Builder nodes, as well as Single Functions to build a complete material. For the red velvet material of the crown we could use a _3delightSkin material, which gives us the ability to use subsurface scattering for a nice, premium velvet effect. There is also a _3delightMetal preset followed by a master material called _3delightMaterial.
Step 08 – Render the final image
For the framebuffer we’re using KATANA’s monitor, which means all images will appear over there and will be saved into the catalogue. To start a render simply Ctrl/right-click on a node – preferably the Render node – and choose a preview image or the Rendering To Disc mode, which will save the image or sequence into the specified folder that was set in the DlSettings node.