Gaffer: Cameras, Render Setup and Catalogues [6/8] (Patreon)

We're entering the home stretch! Just a few more topics to cover before we produce some beautiful final renders.

At this point we have our USD chess set posed, animated, lit and fully assigned with materials. Now we can start creating lookdev renders, but first we'll need a camera or two.

At the top of our node graph, put down two Camera nodes and set the names to cam_main and cam_close. Add them to a new Group called cam and connect it to our main MergeScenes. The cam group and the two cameras are now listed in the Hierarchy View.

Cameras can be positioned just like any other object in the Viewer. We can also use the camera menu to look through a specific camera. 

Let's look through cam_main, then enable the CameraTool on the left side toolbar to lock the camera to the viewport controls. This way we can position the camera by navigating around the scene using standard 3D controls. Use F to center the view on any selected geometry.

Position cam_main with a view of the whole chess set and cam_close framing one piece up close. We can leave all the camera parameters at their default values, except for one minor detail. There's another small bug in Cycles: cameras need to be different in some way in order to enable switching between render cameras. To work around this, set cam_close to have a Near Clipping Plane of 0.001. This will have no material impact on the scene, but now the cameras are "different" for Cycles' purposes.

Moving on, let's head to the very bottom of the node graph to establish the render settings for our scene. First up, connect a StandardOptions node. This contains all the general render settings for our images. We won't need to change many defaults, but for now choose cam_main as the render camera and set the resolution to 1920 x 1080.

We'll also need a CyclesOptions node to configure Cycles. I found GPU rendering to be very responsive in this scene, so I set the Device to CUDA:00 (meaning the first CUDA device on my system) and the Shading System to SVM (the other option, OSL, is CPU-only).

In the Sampling section I turned on Adaptive Sampling (always my go-to in any renderer than supports it) and set the Adaptive Threshold to 0.01. I also set the Samples to a high number, 5000. The main thing we want here is the adaptive threshold to be hit before we reach max samples. With a threshold of 0.01 we won't get close to 5000 total samples, but when we lower the threshold for the final renders we likely will.

We're just about ready render! Gaffer includes a powerful tool called a Catalogue to view, store and compare images. Add a Catalogue node and set it off to the side; it doesn't need to be connected to the rest of the node graph.

You might notice a little star with a 2 there. What is it?! This is another very useful feature in Gaffer: bookmarks. Right click on a node and set a Numeric Bookmark, or use the Ctrl-<bookmark number> keyboard shortcut. This lets us jump to any node in the graph that has a bookmark simply by pressing the appropriate number on the keyboard.

We can also quickly focus bookmarked nodes. Any time we want to focus the Catalogue all we have to do is press Alt-2 (or whichever number you assigned to it). Go ahead and do that: the Catalogue is now focused and the Viewer changes to show the images contained in the Catalogue. No images yet, but there will be soon!

One more thing: we need an Outputs node. This is where we tell Gaffer what type of images we're creating. There are two workflows, Interactive and Batch. Batch is for rendering to disk and Interactive is for rendering to our new Catalogue, so in this case we'll select Interactive/Beauty.

Set a custom name under catalogue:imageName if you want (this is the prefix that will be given to renders stored in the Catalogue). 

By default, an Interactive render will be sent to whatever existing unnamed Catalogue is in the scene. This works fine, but it will get confusing if we ever have more than one Catalogue. To be safe, we can point to a specific Catalogue. 

 To do so, in the Catalogue, type a custom value in the Name parameter under the Settings tab.

In the Outputs node, click the plus icon, create a value called catalogue:name and type in the same name you chose above.

Rendering time! Attach an InteractiveRender node, choose Cycles from the dropdown and press the play button. 

In a few seconds we should see our scene in all its glory:

(Note that a few screenshots will show outdated node names following the release of Gaffer 1.4. The tutorial text is updated so you'll still be able to follow along no problem!)

The InteractiveRender node will show log info in the Node Editor, plus any warnings or errors. The render can now be controlled via the Play/Pause and Stop buttons on the top right of the Viewer. Pressing Stop will save the image to the Catalogue.

Saving images allows us to easily compare renders and iterate through various settings and looks. Images can be deleted, renamed and annotated. 

We can wipe between renders using Compare Mode in the Viewer. Select an image, then pick another image to compare by assigning it to Output Index number 1 as shown in the clip below.

There is also a Crop Window Tool for isolating a small portion of the image:

Leaving the render live, we can use the Light Editor to change lights or navigate through the node graph to edit materials, all while enjoying instant feedback in the Viewer. Now is the time to apply everything we've learned up until this point to test out different render settings, position cameras, update materials and more as we dial in the final look of the scene. 

Before we finish, we need to add one more detail: displacement. Click on over to Part 7 where we cover how to enable displacement in Cycles!